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Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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19 pages, 3881 KB  
Article
Mechanical Properties of 3D-Printed ABS Composites Reinforced with Multi-Scale Carbon/Kevlar Hybrid Fibers
by Shaoqi Dong, Shixian Li and Wanying Zhu
Materials 2026, 19(13), 2690; https://doi.org/10.3390/ma19132690 - 23 Jun 2026
Viewed by 262
Abstract
Fused deposition modeling (FDM) provides a flexible manufacturing route for continuous fiber-reinforced thermoplastic composites, but weak interlaminar bonding and the trade-off between load-bearing capacity and deformation capability still limit their structural applications. In this study, multi-scale carbon/Kevlar fiber hybridization was introduced into acrylonitrile [...] Read more.
Fused deposition modeling (FDM) provides a flexible manufacturing route for continuous fiber-reinforced thermoplastic composites, but weak interlaminar bonding and the trade-off between load-bearing capacity and deformation capability still limit their structural applications. In this study, multi-scale carbon/Kevlar fiber hybridization was introduced into acrylonitrile butadiene styrene (ABS)-based composites by combining continuous carbon fiber (CCF) or continuous Kevlar fiber (CKF) with short carbon fiber-filled ABS (ABS/SCF) or short Kevlar fiber-filled ABS (ABS/SKF). Four hybrid configurations and two continuous-fiber baseline composites were fabricated by FDM and evaluated through three-point bending tests, floating roller peel tests, peeled-surface SEM observations, and Rule-of-Mixtures-based hybrid effect analysis. The flexural results showed that short-fiber-filled matrices improved the flexural properties of both CCF- and CKF-based composites, but the degree of improvement depended on the fiber combination. Among the investigated configurations, CCF + ABS/SCF exhibited the highest flexural modulus and strength, which were 34.31% and 27.26% higher than those of CCF + ABS, respectively. For the CKF-based composites, CKF + ABS/SCF increased the flexural modulus and strength by 31.51% and 26.78%, compared with CKF + ABS, while maintaining the progressive deformation behavior associated with Kevlar reinforcement. The peel results showed that all hybrid composites had higher interlaminar peel resistance than their corresponding baselines, with increases ranging from 18.66% to 54.42%. The peeled-surface SEM observations indicated that the short-fiber-filled matrices changed the crack-propagation features, with more matrix tearing, fiber pull-out, and irregular peeling areas. The RoM-based comparison showed that the measured flexural properties of all hybrid configurations were higher than the corresponding RoM reference values. Overall, CCF + ABS/SCF was more suitable for improving stiffness and load-bearing capacity, whereas CKF + ABS/SCF showed a more balanced response in terms of flexural performance, interlaminar peel resistance, and progressive deformation behavior. Full article
(This article belongs to the Special Issue Structural Design and Mechanical Properties of Fiber Composites (Second Edition))
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14 pages, 3149 KB  
Article
Anisotropic Graphene Oxide Aerogels for Vegetable Oil Absorption
by Daniel Ordóñez Oviedo, Nelly Maria Rosas-Laverde, Arturo Barjola, Enrique Giménez and Alina Iuliana Pruna
Materials 2026, 19(12), 2680; https://doi.org/10.3390/ma19122680 - 22 Jun 2026
Viewed by 174
Abstract
Oil spills represent a critical environmental challenge. The wastewater treatment with porous sorbents presents the advantage of higher uptake and recyclability. In this work, highly porous and low-density three-dimensional reduced graphene oxide aerogels were obtained by hydrothermal reduction followed by lyophilization. The porosity [...] Read more.
Oil spills represent a critical environmental challenge. The wastewater treatment with porous sorbents presents the advantage of higher uptake and recyclability. In this work, highly porous and low-density three-dimensional reduced graphene oxide aerogels were obtained by hydrothermal reduction followed by lyophilization. The porosity and reduction degree of the aerogels were controlled by the addition of reducing species, namely ethylenediamine, and hydrothermal conditions. The aerogels were characterized using scanning electron microscopy, Raman spectroscopy, and energy-dispersive X-ray analysis. The sorption measurements were performed with vegetable oils, namely canola and olive oil, at varying operating temperatures. The morphological analysis revealed a well-defined porosity gradient along the aerogel length, along with a functionalization gradient. The sorption performance is highly dependent on their combined action. The maximum gravimetric absorption capacity was about 122 g g−1 at room temperature, increasing to 156 g g−1 at 60 °C, with the absorption rate increasing from about 1 g g−1 s−1 to 15 g g−1 s−1 within 10 s. These results demonstrate that anisotropic gradient aerogels could be obtained by simple tailoring of the synthesis conditions, and such aerogels could benefit the sorption of oils with higher viscosities in terms of rate, pore filling and retention. Full article
(This article belongs to the Section Carbon Materials)
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22 pages, 3931 KB  
Article
One-Pot Sr-Free LaFeO3/CeO2-Based Electrocatalytic Composites: Effect of Cerium and Lanthanum Interplay Between Perovskite and Fluorite
by Laura Valentino, Francesca Deganello, Leonarda Francesca Liotta, Giuseppe Marcì and Chiara Aliotta
Materials 2026, 19(11), 2361; https://doi.org/10.3390/ma19112361 - 2 Jun 2026
Viewed by 786
Abstract
Perovskite-type oxides are among the most promising cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to their mixed ionic–electronic conductivity and compositional flexibility. Many high-performance cathodes rely on Sr substitution at the A-site, often associated with surface segregation and long-term degradation. In [...] Read more.
Perovskite-type oxides are among the most promising cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to their mixed ionic–electronic conductivity and compositional flexibility. Many high-performance cathodes rely on Sr substitution at the A-site, often associated with surface segregation and long-term degradation. In this work, we explore an alternative strategy based on defect engineering and phase interactions in Sr-free composites. Perovskite-fluorite composites based on LaFe0.8Co0.2O3 were synthesized through a one-pot route designed to promote the formation of a perovskite phase and a limited amount of fluorite-type ceria. This approach allows the introduction of small fractions of Ce into the perovskite lattice, favoring the cooperative coexistence with La-doped CeO2. Structural, microstructural and spectroscopic characterization indicates that Ce influences the crystallization pathway and composite defect chemistry. Variations in lattice parameters and Raman features suggest modifications of perovskite structure consistent with defect formation and lattice distortion. Reduction properties and electrical conductivity measurements indicate that Ce incorporation in the perovskite and oxide interaction affect charge transport and oxygen mobility. The electrochemical results demonstrate that the optimal trade-off between activation energy (Ea) and polarization resistance (Rp) is achieved for the sample, with a nominal cerium content, Ce/(La + Ce) of 0.16. Moreover, the electrochemical properties are found to correlate with the nominal cerium content, which regulates defect chemistry and the resulting composite composition. Overall, results suggest that the one-pot synthesis promotes beneficial interactions between the perovskite and ceria phases, allowing the development of Sr-free ferrite-based materials with enhanced functional properties, minimizing the amount of ceria in the composite. Full article
(This article belongs to the Special Issue Application of Electrocatalytic and Electrochemical Materials in Energy)
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24 pages, 10631 KB  
Article
Non-Destructive Characterization of Cultural Heritage Materials Using a Modified Acoustic Resonance Approach
by Filip Pantelić, Miloš Radomir Vasić, Marko Stojanović, Anja Terzić, Bojan Miljević and Snežana Vučetić
Materials 2026, 19(11), 2291; https://doi.org/10.3390/ma19112291 - 28 May 2026
Viewed by 269
Abstract
This study explores non-destructive techniques for characterizing the mechanical properties of materials pertinent to cultural heritage, emphasizing the preservation of sample integrity. A modified acoustic resonance method (MARM), utilizing a two-microphone configuration, is introduced for the simultaneous, fully non-contact determination of dynamic elastic [...] Read more.
This study explores non-destructive techniques for characterizing the mechanical properties of materials pertinent to cultural heritage, emphasizing the preservation of sample integrity. A modified acoustic resonance method (MARM), utilizing a two-microphone configuration, is introduced for the simultaneous, fully non-contact determination of dynamic elastic modulus and damping (loss factor). The method is validated through comparison with the impulse excitation technique (IET) and ultrasonic pulse velocity testing (UT). The approach is applied to two material categories exhibiting contrasting porosities: dense natural stone and highly porous unfired clay. Results demonstrate strong concordance among all methods for stone, confirming the reliability of non-destructive techniques for homogeneous materials. Conversely, unfired clay displays greater variability attributable to its heterogeneous and porous nature, alongside increased damping. This investigation reveals that conventional modulus–strength correlations are not directly applicable to unfired clay. To address this, a simplified strength estimation model incorporating the estimated elastic modulus and porosity is proposed. The model achieves improved alignment with experimental data and delineates applicability boundaries for porous materials. The presented framework facilitates consistent, non-destructive evaluation of mechanical properties, with notable implications for the assessment and preservation of cultural heritage materials. Full article
(This article belongs to the Section Advanced Materials Characterization)
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26 pages, 34335 KB  
Article
Investigating Process–Structure–Property Relationships in Large-Scale Additively Manufactured Carbon-Filled PETg
by Christopher Bock, Brett Ellis and Masoud Rais-Rohani
Materials 2026, 19(11), 2270; https://doi.org/10.3390/ma19112270 - 27 May 2026
Viewed by 416
Abstract
Properties of a material fabricated by large-scale additive manufacturing exhibit strong process dependence by way of processing and microstructure. This study seeks to experimentally evaluate this process–structure–property linkage for carbon-fiber-reinforced PETg. To facilitate this investigation, an experimental design involving eight different combinations of [...] Read more.
Properties of a material fabricated by large-scale additive manufacturing exhibit strong process dependence by way of processing and microstructure. This study seeks to experimentally evaluate this process–structure–property linkage for carbon-fiber-reinforced PETg. To facilitate this investigation, an experimental design involving eight different combinations of layer height, feed rate, bead spacing and screw speed in the printing process is considered. Forty-five microstructure specimens are excised and imaged to reveal the fiber orientation and porosity, and nearly 180 flexural samples are tested to evaluate their strength and stiffness. Measured mean values for modulus along the bead range from 13.3 to 18.6 GPa, and for strength, it is between 158 to 189 MPa. Mean values for the inter-layer stiffness range from 2.9 to 3.2 GPa, and for strength, it ranges between 31.4 and 45.0 MPa. Results indicate a strong relationship between screw speed and fiber orientation and between fiber orientation and stiffness and strength. Additional insights into the fracture behavior of the material are provided using high-speed photography of the moment of fracture and microscopy of the fracture surfaces. This work provides a cohesive process–structure–property dataset that can be used as a reference for validation of process–structure, structure–property, and process–structure–property models. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
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33 pages, 15100 KB  
Article
Effects of Heat Treatment Procedures and Diamond Burnishing on Tensile Properties and Surface Integrity of Additively Manufactured 17-4PH Steel Cylindrical Parts
by Galya Duncheva, Jordan Maximov, Vladimir Dunchev, Angel Anchev, Vladimir Todorov, Yaroslav Argirov, Kalin Anastasov and Hristian Mitev
Materials 2026, 19(11), 2192; https://doi.org/10.3390/ma19112192 - 22 May 2026
Viewed by 417
Abstract
This article presents a new combined post-processing concept to improve the quality of laser powder bed fusion (LPBF) of 17-4PH stainless steel (SS) cylindrical parts fabricated from N2-atomised LaserForm 17-4PH (B) powder. The concept is based on consecutive heat treatment procedures [...] Read more.
This article presents a new combined post-processing concept to improve the quality of laser powder bed fusion (LPBF) of 17-4PH stainless steel (SS) cylindrical parts fabricated from N2-atomised LaserForm 17-4PH (B) powder. The concept is based on consecutive heat treatment procedures and diamond burnishing (DB) processes. A two-stage study was conducted. The first stage was an LPBF process experiment. The following combination of LPBF parameter values was selected after optimisation: a laser power of P=150 W, laser scanning speed of v = 1200 mm/s, and layer thickness of t=40 μm. In the second stage, this combination was used to evaluate the effects of two heat treatment procedures (HT1 and HT2) and two DB processes (using burnishing forces of 100 N and 300 N) on the tensile properties and surface integrity of LPBF 17-4PH SS cylindrical samples. The HT2 procedure, including annealing (1200∘, 4 h), solution treatment (1060∘, 1 h), cooling (−70 ∘C,2 h), and ageing (482∘, 4 h) led to yield limit, tensile strength, and Vickers hardness values of YL=1071 MPa, TS=1410 MPa, and 523 HV, respectively. The concept presented takes advantage of the combination of the transformation, precipitation and strain-hardening effects. The combined effect was most pronounced in the samples subjected to the HT2 procedure and subsequent DB (300 N), for which a retained austenite fraction of 6.93%, surface microhardness of 563 HV0.05 and the maximum values of the compressive axial and hoop RSs of −1426.3 MPa and −1095.9 MPa, respectively, were measured. Full article
(This article belongs to the Special Issue Advanced Welding Technologies and Additive Manufacturing of Alloys and Metals (3rd Edition))
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20 pages, 6365 KB  
Article
Topological Weyl and Nodal Line Half-Metals in Two-Dimensional van der Waals Material EuOX (X = F, Cl, Br, I)
by Sheng-Hsiung Hung and Horng-Tay Jeng
Materials 2026, 19(10), 2154; https://doi.org/10.3390/ma19102154 - 21 May 2026
Viewed by 369
Abstract
Two-dimensional magnetic materials with an atomic-thick layered structure have long been a focal point in condensed matter physics owing to the intrinsic long-range magnetic order, the monolayer limit with high tunability and potential in nano-scale spintronics. In this study, we report a novel [...] Read more.
Two-dimensional magnetic materials with an atomic-thick layered structure have long been a focal point in condensed matter physics owing to the intrinsic long-range magnetic order, the monolayer limit with high tunability and potential in nano-scale spintronics. In this study, we report a novel family of two-dimensional (2D) materials, EuOX (where X = F, Cl, Br, I), displaying 2D half-metallicity with topological properties. Specifically, the spin-up conducting channel demonstrates metallic behavior, while the spin-down channel exhibits an insulating band gap at the Fermi level. The presence of Weyl points and nodal lines coexists in the spin-up conductive channel of EuOX monolayers. These topological properties, alongside the half-metallic behavior, evolve systematically with the strong-correlation Hubbard U. These findings provide crucial insights into the design of 2D topological spintronic devices, offering a promising platform for future spintronic applications in the nano scale. Full article
(This article belongs to the Section Materials Physics)
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13 pages, 2995 KB  
Article
Influence of Nickel Content and Heat Treatment Parameters on Kinetics of Crystallisation, Magnetic Properties and Brittleness of Nanocrystalline Fe-Ni-B Alloys Obtained by Ultra-Rapid Annealing with Joule Heating
by Jarosław Ferenc, Zofia Czyżewska, Maciej Kowalczyk, Krzysztof Sielicki and Dariusz Oleszak
Materials 2026, 19(10), 2157; https://doi.org/10.3390/ma19102157 - 21 May 2026
Viewed by 469
Abstract
Metallic glasses can be transformed into nanocrystalline–amorphous alloys via controlled crystallisation with fast nucleation and slow grain growth. This can be achieved either through appropriate chemical composition of amorphous precursors or by applying ultra-rapid annealing (URA). Typically, heating between preheated copper blocks is [...] Read more.
Metallic glasses can be transformed into nanocrystalline–amorphous alloys via controlled crystallisation with fast nucleation and slow grain growth. This can be achieved either through appropriate chemical composition of amorphous precursors or by applying ultra-rapid annealing (URA). Typically, heating between preheated copper blocks is used to ensure the URA conditions. In this work, ribbons were heated by an electric current flowing along their length, and the temperature was monitored using pyrometers. The investigated alloys were Fe86-xNixB14 (at. %), where x = 4, 6 or 10. Properly adjusted isothermal annealing at 380–410 °C for 1–20 s induced crystallisation, with the nanocrystalline bcc-Fe(Ni) phase occupying 0–55% of the volume. With increasing annealing time, the coercive field increased from 9 A/m in the amorphous state to 25 A/m and 17 A/m for x = 4 and x = 10, respectively. Transmission electron microscopy confirmed that samples annealed at higher temperatures for shorter times exhibited smaller grain sizes compared to those annealed at lower temperatures for longer times, which resulted in improved magnetic softness. An increase in nickel content reduced coercivity, improved ductility, and offered a wider window for the choice of annealing temperature. Full article
(This article belongs to the Special Issue Advances in Magnetic Materials and Applications)
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21 pages, 11838 KB  
Article
Process Strategies Enabling Selective Polymer Valorization from Textile Fiber Blends
by Diana Smarandache, Bruno Godinho, Marina Matos, Susana C. Pinto, Cătălina Ionescu, Nicoleta Cioateră, Artur Ferreira and Nuno Gama
Materials 2026, 19(10), 2100; https://doi.org/10.3390/ma19102100 - 16 May 2026
Viewed by 327
Abstract
The increasing complexity of textile waste, particularly blended fibers, represents a major challenge for conventional recycling approaches. This study proposes a selective valorization strategy for mixed textile waste streams by applying tailored chemical recycling routes to individual fiber type. Preliminary tests identified suitable [...] Read more.
The increasing complexity of textile waste, particularly blended fibers, represents a major challenge for conventional recycling approaches. This study proposes a selective valorization strategy for mixed textile waste streams by applying tailored chemical recycling routes to individual fiber type. Preliminary tests identified suitable methodologies for each fiber type: dissolution–precipitation for acrylic (poly(acrylonitrile)—PAN), acidolysis for nylon, glycolysis for polyester (PeS) and acetylation for cotton. Structural characterization confirmed that the incorporation of recycled products did not significantly change the chemical structure or crystallinity of the resulting materials. Furthermore, thermal analysis revealed comparable or slightly improved thermal stability in most recycled systems. Additionally, mechanical performance was observed to vary depending on the polymer type. Recycled acrylic and cellulose acetate showed reduced ductility, while nylon exhibited increased stiffness due to possible recrystallization effects. In contrast, PeS displayed enhanced elongation at break, suggesting increased chain mobility or plasticization effects. Overall, the results demonstrate that selective chemical valorization is a promising route for the efficient recycling of complex textile waste, enabling the recovery of high-quality materials with retained functional properties. Full article
(This article belongs to the Special Issue Advanced Materials for Circularity: Recycling of Polymer Blends and Composites)
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15 pages, 5177 KB  
Article
Influence of Particle Size and Mineralogical Composition on the Mechanical and Tribological Properties of Resin-Regolith-Composites for Non-Structural Applications
by Nicola Calisi, Stefano Caporali and Rosa Taurino
Materials 2026, 19(10), 2066; https://doi.org/10.3390/ma19102066 - 15 May 2026
Viewed by 344
Abstract
The development of resin-regolith composites represents a promising In Situ Resource Utilization (ISRU) strategy for future lunar missions. While unsuitable for primary habitat construction due to the payload cost of transporting polymers from Earth, these composites offer a highly efficient solution for manufacturing [...] Read more.
The development of resin-regolith composites represents a promising In Situ Resource Utilization (ISRU) strategy for future lunar missions. While unsuitable for primary habitat construction due to the payload cost of transporting polymers from Earth, these composites offer a highly efficient solution for manufacturing non-structural, everyday items (e.g., containers, tools, and plant cultivation pots) directly on the Moon via mold–casting. This approach significantly reduces the volume and mass of pre-formed plastic payloads. In this work, the influence of the particle size distribution of a lunar highland simulant (LHS-1E) on the mechanical properties of epoxy-based composites was systematically investigated for such applications. First, the regolith-to-resin ratio was optimized for castability, establishing a maximum regolith content of 60 wt.%. Then, four different size fractions of the simulant were prepared by sieving (>200 µm, 200–100 µm, 100–50 µm, and <50 µm), and composite samples were cast maintaining this optimal ratio. X-ray microtomography revealed that using larger particles (>200 µm) increased composite porosity, whereas smaller fractions promoted more compact structures. Three-point bending tests showed that intermediate particle sizes (200–100 µm and 100–50 µm) led to enhanced flexural strength, while the smallest particles (<50 µm) decreased mechanical performance, likely due to a lower basalt content in this finer fraction. Finally, ball-on-disk tribological analyses highlighted that composites made with larger particles (>200 µm) exhibited superior wear resistance, whereas particle size had negligible effects on the coefficient of friction. Overall, the results demonstrate that both particle size and mineralogical composition significantly influence the performance of regolith–epoxy composites, providing essential guidelines for the in situ manufacturing of functional, non-structural objects for lunar outposts. Full article
(This article belongs to the Section Advanced Composites)
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29 pages, 42206 KB  
Article
Acoustic Source Localisation of Crack Initiation During Laser-Based DED: Experimental Validation and Challenges
by Md Jonaet Ansari, Elias J. G. Arcondoulis, Anthony Roccisano, Christiane Schulz, Thomas Schläfer and Colin Hall
Materials 2026, 19(10), 1967; https://doi.org/10.3390/ma19101967 - 10 May 2026
Viewed by 320
Abstract
This study evaluates the feasibility of airborne acoustic source localisation (ASL) for in situ crack localisation in industrial laser-based directed energy deposition (DED-LB/M) fabricated structures. A four-microphone array combined with a Generalised Cross-Correlation with Phase Transform (GCC-PHAT) algorithm was used to estimate crack [...] Read more.
This study evaluates the feasibility of airborne acoustic source localisation (ASL) for in situ crack localisation in industrial laser-based directed energy deposition (DED-LB/M) fabricated structures. A four-microphone array combined with a Generalised Cross-Correlation with Phase Transform (GCC-PHAT) algorithm was used to estimate crack positions from time differences of arrival (TDOAs) extracted from raw acoustic emissions during multi-layer single-track fabrication. Prior to experimentation, the microphone array geometry was numerically optimised under industrial placement constraints by introducing controlled TDOA perturbations and minimising three-dimensional localisation uncertainty using alpha-shape volume analysis. Experimental validation was performed on six-layer single-track structures, with estimated crack positions compared against post-process microscopic measurements. Localisation errors ranged from 12 to 68 mm in the X-direction, 0.7–32 mm in the Y-direction, and 5–100 mm in the Z-direction. While horizontal localisation demonstrated centimetre-scale accuracy for most cracks, depth estimation exhibited greater variability. The results confirm that airborne ASL can provide meaningful spatial information regarding crack formation during DED-LB/M. However, localisation performance remains sensitive to TDOA estimation accuracy, microphone array constraints, and the complex acoustic environment inherent to the process. This work demonstrates the industrial feasibility of ASL for in situ crack investigation while highlighting the need for further advancements in array design and signal processing to achieve robust three-dimensional defect localisation in additive manufacturing systems. Full article
(This article belongs to the Special Issue Additive and Subtractive Manufacturing of Advanced Material: Modeling and Surface Integrity)
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28 pages, 4810 KB  
Article
Recycled Polypropylene Composites Reinforced with Microcellulose Fibres and Microcellulose-Derived Biochar: Thermal, Rheological and Mechanical Performance
by Wiktor Wyderkiewicz, Justyna Miedzianowska-Masłowska, Anna Sowińska-Baranowska and Marcin Masłowski
Materials 2026, 19(10), 1942; https://doi.org/10.3390/ma19101942 - 9 May 2026
Viewed by 429
Abstract
The mechanical recycling of mono-material biaxially oriented polypropylene (BOPP) packaging films produces recycled polypropylene (rPP) with degraded properties, limiting its use in higher-performance applications. This study investigates rPP reinforcement with 6–12 µm microcellulose fibres (MCFs, 2–10 pbw) and microcellulose-derived biochar (BC, 5–20 pbw), [...] Read more.
The mechanical recycling of mono-material biaxially oriented polypropylene (BOPP) packaging films produces recycled polypropylene (rPP) with degraded properties, limiting its use in higher-performance applications. This study investigates rPP reinforcement with 6–12 µm microcellulose fibres (MCFs, 2–10 pbw) and microcellulose-derived biochar (BC, 5–20 pbw), characterized by DSC, TGA/DTG, MVR/MFR, temperature-dependent rheology, mechanical testing and water contact angle (WCA) measurements. Both fillers acted as heterogeneous nucleating agents, shifting crystallization by up to 4 °C and increasing crystallinity by 2–4%. MCF introduced an additional low-temperature degradation step, whereas BC increased onset and peak degradation temperatures by up to 20 °C and increased char yield. Low MCF loadings increased MVR/MFR by 20–25% and reduced melt viscosity, while BC decreased flow indices by up to 50% and stiffened the melt. Tensile and flexural moduli increased by 15–25% with MCF and 40–50% with BC, with a stiffness–toughness trade-off at the highest BC contents. MCF reduced the water contact angle to 63.0° at 10 pbw, while BC increased it to 108.1° at 20 pbw, indicating opposite effects on surface wettability. Converting a single cellulosic feedstock into fibrous or carbonised fillers enables bio-based upgrading of rPP, in line with circular economy principles. Full article
(This article belongs to the Special Issue Advanced Polymer Matrix Nanocomposite Materials (3rd Edition))
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21 pages, 1390 KB  
Perspective
Calcination of Ca-Based Sorbents in the Presence of Steam for Sorption-Enhanced Gasification Applications
by William A. González, Susanna Nilsson, Diego Fuentes-Cano, Alicia Ronda and Alberto Gómez-Barea
Materials 2026, 19(10), 1959; https://doi.org/10.3390/ma19101959 - 9 May 2026
Viewed by 435
Abstract
The calcination kinetics of limestone and dolomite under conditions relevant to sorption-enhanced gasification (SEG) were investigated: mild temperature (775–850 °C), low CO2 partial pressure (0.05–0.10 bar), and a steam-rich (H2O balance) atmosphere. Experiments with two Ca-based sorbents (limestone and dolomite) [...] Read more.
The calcination kinetics of limestone and dolomite under conditions relevant to sorption-enhanced gasification (SEG) were investigated: mild temperature (775–850 °C), low CO2 partial pressure (0.05–0.10 bar), and a steam-rich (H2O balance) atmosphere. Experiments with two Ca-based sorbents (limestone and dolomite) were conducted in a fluidized bed reactor to assess both initial calcination kinetics and multicycle deactivation during 10 cycles under SEG carbonation conditions at 650 °C. Dolomite exhibited markedly higher calcination rates than limestone, which is consistent with the structural modifications induced by MgCO3 decomposition and the presence of MgO, resulting in a slightly lower apparent activation energy (115.96 kJ mol−1 for dolomite compared to 120.27 kJ mol−1 for limestone). Both sorbents showed a strong sensitivity to the deviation from the equilibrium CO2 partial pressure, with reaction orders near 2. The presence of steam was confirmed to have a significant catalytic effect, accelerating the first-cycle calcination rate compared to dry N2 conditions. Sorbent deactivation caused by sintering was more pronounced at higher temperatures and CO2 pressures. Dolomite showed significantly less deactivation, compared to limestone, which can be attributed to the increase in structural stability due to the presence of MgO. The kinetics obtained in this work contribute to the design of stable SEG based on dual fluidized bed reactors, particularly to assist in the selection of calcination operating conditions to minimize sorbent deactivation and in the development of stable CO2-sorbents. Full article
(This article belongs to the Section Energy Materials)
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28 pages, 12481 KB  
Article
Quantitative Damage Detection and Evolution in Composite Structures Using Digital Image Correlation, Machine Learning, and Peridynamics
by Tomas Vaitkūnas, Elena Jasiūnienė, Justas Griškevičius, Vykintas Samaitis and Paulius Griškevičius
Materials 2026, 19(10), 1917; https://doi.org/10.3390/ma19101917 - 7 May 2026
Viewed by 390
Abstract
Structural health monitoring (SHM) of composite structures using surface strain fields measured by digital image correlation (DIC) has been widely demonstrated; however, accurate damage quantification remains challenging. This study proposes a hybrid framework integrating finite element (FE) modeling, machine learning (ML), and peridynamics [...] Read more.
Structural health monitoring (SHM) of composite structures using surface strain fields measured by digital image correlation (DIC) has been widely demonstrated; however, accurate damage quantification remains challenging. This study proposes a hybrid framework integrating finite element (FE) modeling, machine learning (ML), and peridynamics (PD). A CFRP specimen with a notch was subjected to cyclic loading, and damage evolution was monitored using DIC and validated by ultrasound measurements. A validated FE model generated synthetic strain-field datasets for ML training, enabling defect detection and quantitative characterization directly from surface strains. The trained models achieved high accuracy, including perfect notch detection and low prediction errors. A calibrated PD model captured internal damage evolution and fatigue behavior. The combined DIC–ML–PD approach enables accurate, non-contact damage identification and prognosis, supporting physics-informed digital twins for composite structures. Full article
(This article belongs to the Special Issue Intelligent Damage Detection of Materials and Structural Health Monitoring Technology)
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18 pages, 2217 KB  
Article
Grain-Size-Dependent Hydrogen Evolution and Oxygen Evolution Reaction Behavior of a Non-Equiatomic Fe41Mn25Ni24Co8Cr2 High-Entropy Alloy
by Hee-Tae Jeong and Woo Jin Kim
Materials 2026, 19(9), 1899; https://doi.org/10.3390/ma19091899 - 5 May 2026
Viewed by 509
Abstract
The grain-size dependence of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) behavior was systematically investigated in a non-equiatomic Fe41Mn25Ni24Co8Cr2 high-entropy alloy. Six fully recrystallized specimens spanning grain sizes from 5.1 to 197 [...] Read more.
The grain-size dependence of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) behavior was systematically investigated in a non-equiatomic Fe41Mn25Ni24Co8Cr2 high-entropy alloy. Six fully recrystallized specimens spanning grain sizes from 5.1 to 197 μm, produced by high-ratio differential speed rolling (HRDSR) and controlled annealing, were tested in 1 M KOH. Differential local Tafel-slope analysis revealed distinct and asymmetric grain-size-dependent behavior for the two half-reactions. For HER, the local Tafel slope at −3 mA cm−2 showed the clearest correlation with log(d/μm) among the HER descriptors examined in the present dataset (R2 = 0.682), indicating that grain-size effects were most clearly expressed in the near-onset to intermediate current-density regime. For OER, finer-grained specimens consistently exhibited more favorable apparent performance: the overpotential at 10 mA cm−2 increased with log(d/μm) (R2 = 0.715; slope = 1.09 × 10−2 V dec−1), whereas the current density at an overpotential of 0.33 V decreased with grain size (j0.33; R2 = 0.787). Overall, OER showed stronger and more consistent grain-size dependence than HER. These results identify grain size as a useful empirical microstructural descriptor of apparent electrocatalytic response in this composition-fixed bulk HEA system and show that microstructural control provides a practical route for tuning alkaline HER and OER behavior. Full article
(This article belongs to the Special Issue Advances in Catalytic Materials and Their Applications)
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14 pages, 15026 KB  
Article
Electrospun Poly(vinylpyrrolidone)/Thymus vulgaris L. Mats for the Protection of Fresh Berries Against Spoilage
by Erika Adomavičiūtė, Egidijus Griškonis, Visvaldas Varžinskas and Virginija Jankauskaitė
Materials 2026, 19(9), 1874; https://doi.org/10.3390/ma19091874 - 1 May 2026
Viewed by 509
Abstract
The use of non-biodegradable plastic food packaging materials has become a major environmental concern. These plastics release chemicals and microplastics during degradation, harming wildlife and entering the food chain, posing risks to both environmental and human health. This study aimed to evaluate electrospun [...] Read more.
The use of non-biodegradable plastic food packaging materials has become a major environmental concern. These plastics release chemicals and microplastics during degradation, harming wildlife and entering the food chain, posing risks to both environmental and human health. This study aimed to evaluate electrospun poly(vinylpyrrolidone) (PVP) mats incorporating natural antibacterial Thymus vulgaris L. extract (TE) and natural crosslinker citric acid (CA) as alternative food packaging materials. Packaging mats with TE and/or CA combinations in PVP were evaluated for their structural, chemical, optical, and shelf-life-enhancing effects on blueberries. The results show that dissolving PVP in TE extract and adding CA in PVP ethanol-water or TE-based solutions significantly affected the viscosity and conductivity of the electrospinning solutions, thereby influencing the morphology of electrospun mats. FTIR analysis confirmed the incorporation of TE into the polymer and indicated CA induced hydrogen bonding, interactions that may reduce the polymer chain mobility and increase the brittleness of the electrospun mat. In tests with blueberries, it was estimated that the commonly used traditional food film minimized blueberry weight loss, whereas the porous electrospun PVP and PVP/TE mats allowed greater moisture release and preserved better visual quality by reducing wrinkling and dehydration. Overall, electrospun PVP-based mats functionalized with TE show promise as sustainable food packaging materials that balance moisture management with product appearance. Full article
(This article belongs to the Special Issue Functional/Structural Polymers and Composites Produced by the Addition of Plant Biomass or Waste Materials Using Various Production Technologies)
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31 pages, 3684 KB  
Review
A Circular Material Value Retention Framework for Agricultural By-Product Valorisation
by Roxane Alizad, Yousef Haddad and Konstantinos Salonitis
Materials 2026, 19(9), 1796; https://doi.org/10.3390/ma19091796 - 28 Apr 2026
Viewed by 337
Abstract
While valorisation pathways are increasingly promoted as sustainable solutions, their ability to genuinely minimise environmental harm and contribute to long-term material circularity remains uneven. This study systematically identifies and maps existing valorisation routes across the EU and UK, with particular attention to their [...] Read more.
While valorisation pathways are increasingly promoted as sustainable solutions, their ability to genuinely minimise environmental harm and contribute to long-term material circularity remains uneven. This study systematically identifies and maps existing valorisation routes across the EU and UK, with particular attention to their environmental performance and economic viability through a material value retention lens. A literature review highlights a spectrum of practices—from soil amendment and composting to bioenergy recovery and bio-based construction materials—each offering different sustainability benefits but varying significantly in their capacity to preserve material quality and function. To address the absence of robust comparative approaches, this paper introduces a novel evaluative framework centred on intrinsic material value retention, a key principle in sustainable and circular material systems. Building on established scholarship, the framework provides a structured means of comparing valorisation options based on how effectively they conserve material properties, particularly in terms of the material’s structural and functional values, and enable high-value reuse. Supported by a dedicated classification tool and a set of guiding questions refined through expert interviews, the framework complements existing environmental assessment methods by foregrounding material circularity. In doing so, it supports more integrated, holistic decision-making for the development of a resilient and sustainable circular bioeconomy. This research is intended for academic audiences and may also be of relevance to industry practitioners. Full article
(This article belongs to the Section Green Materials)
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30 pages, 1378 KB  
Perspective
Modeling of Biomechanical and Functional Parameters of Hydrogel–Cell Composites Fabricated by 3D Bioprinting Using AI-Supported Approach
by Izabela Rojek, Maciej Gniadek, Jakub Kopowski, Tomasz Kloskowski and Dariusz Mikołajewski
Materials 2026, 19(8), 1637; https://doi.org/10.3390/ma19081637 - 19 Apr 2026
Viewed by 482
Abstract
3D bioprinting of hydrogel–cell composites requires simultaneous consideration of the biomechanical properties of the printed structures, the construct’s geometric stability, and conditions conducive to cell survival and function. Hydrogel cross-linking techniques and their kinetics play a key role in this process, determining the [...] Read more.
3D bioprinting of hydrogel–cell composites requires simultaneous consideration of the biomechanical properties of the printed structures, the construct’s geometric stability, and conditions conducive to cell survival and function. Hydrogel cross-linking techniques and their kinetics play a key role in this process, determining the time of shape fixation, the mechanical strength of the structures, and the mechanical environment in which the cells are located immediately after printing. The relationships between bioprinting parameters, material properties, cross-linking strategies, and the presence of cells are highly nonlinear and often investigated through trial and error, leading to significant time and material costs. This paper proposes an approach based on artificial intelligence-assisted simulation, focusing on computer modeling of the biomechanical and functional parameters of hydrogel–cell composites produced by 3D bioprinting. The methodology is based on data generated from computer simulations and allows for analysis of the impact of printing parameters and different cross-linking strategies on mechanical strength, time-dependent geometric stability, and limitations related to cellular function, including exposure time to non-cross-linked matrices. The use of artificial intelligence methods allows for the integration of simulation results and predictive assessment of material behavior, providing a basis for future optimization of bioprinting parameters and process costs prior to experimental validation. Full article
(This article belongs to the Special Issue Design and Process Strategies for Mechanical Reinforcement in Polymer Additive Manufacturing)
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15 pages, 16547 KB  
Article
Innovative Mycelium Bio-Composites (MB) from Birch Sanding Dust and Chitosan with Enhanced Heavy Metals Sorption Properties
by Oskars Bikovens, Anrijs Verovkins and Ilze Irbe
Materials 2026, 19(8), 1629; https://doi.org/10.3390/ma19081629 - 18 Apr 2026
Viewed by 1282
Abstract
Chitosan is a well-known heavy metal biosorbent and was incorporated into birch sanding dust mycelium bio-composites (MBs). The chitosan-hybridized MBs with different chitosan contents were characterized by microscopy, porous structure analyses (specific surface area and total pore volume), pHpzc, functional group [...] Read more.
Chitosan is a well-known heavy metal biosorbent and was incorporated into birch sanding dust mycelium bio-composites (MBs). The chitosan-hybridized MBs with different chitosan contents were characterized by microscopy, porous structure analyses (specific surface area and total pore volume), pHpzc, functional group content, and FTIR. Microscopy did not reveal any antifungal effect of chitosan on Trametes versicolor. The porous structure of the MBs decreased after hybridization with chitosan. The FTIR spectra and functional group analyses confirmed the presence of chitosan amino groups in the MBs. The chitosan-hybridized MBs were subjected to the adsorption of heavy metals, namely Cu(II) and Cd(II), and the removal percentage and adsorption isotherms were evaluated. Adsorption isotherms were analyzed using the Freundlich and Langmuir models. The results showed a significant increase in the maximum monolayer adsorption capacity for Cu(II), calculated using the Langmuir equation, from <2 mg/g for raw BSD and basic MB without chitosan to 19 mg/g for the MB with 15% chitosan. In the case of Cd(II), no significant increase in adsorption capacity was observed. These findings indicate that hybridization of MBs with chitosan is a promising approach to improve the Cu(II) adsorption capacity of MBs. Full article
(This article belongs to the Special Issue Sustainable and Functional Materials: From Design to Applications)
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15 pages, 6134 KB  
Article
The Influence of Plastic Processing on the Corrosion Resistance of the Alloy Based on the FeAl Intermetallic Phase After Long-Term Oxidation in Air Atmosphere
by Dorota Pasek, Janusz Cebulski, Maria Sozańska, Magdalena Popczyk, Jadwiga Gabor and Andrzej Swinarew
Materials 2026, 19(8), 1597; https://doi.org/10.3390/ma19081597 - 15 Apr 2026
Viewed by 445
Abstract
This work presents a study of oxide-scale development on a B2 FeAl-based alloy (Fe40Al5Cr0.2TiB) during long-term isothermal oxidation at 700 °C in air, with particular emphasis on the effect of plastic processing. Oxidation tests were conducted for 300, 1000, and 2000 h. Surface [...] Read more.
This work presents a study of oxide-scale development on a B2 FeAl-based alloy (Fe40Al5Cr0.2TiB) during long-term isothermal oxidation at 700 °C in air, with particular emphasis on the effect of plastic processing. Oxidation tests were conducted for 300, 1000, and 2000 h. Surface morphology and chemical composition were examined using SEM/EDS, phase composition was identified by XRD, and local oxide thickness was measured by TEM. Surface topography was quantified by optical profilometry using Ra and Rz parameters. In both material states (as-cast and plastically processed), the alloy formed a continuous α-Al2O3-based scale. Plastic processing significantly affected oxidation kinetics, resulting in higher mass gain compared to the as-cast condition. Despite differences in mass gain, the average oxide-scale thickness after 2000 h remained in the submicrometric range (~340 nm) for both states. Surface topography analysis revealed differences in roughness and morphology associated with the material condition. The results demonstrate that plastic processing influences oxidation behavior primarily through microstructural modification, while the protective character of the alumina scale remains preserved. These findings provide data relevant to FeAl-based materials considered for high-temperature energy applications. Full article
(This article belongs to the Special Issue Achievements in Foundry Materials and Technologies (Second Edition))
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18 pages, 4243 KB  
Article
Overall Performance Enhancement of Epoxy Resins Loaded with Non-Covalently Modified Carbon Nanotubes and Graphene Nanosheets
by Marialuigia Raimondo and Liberata Guadagno
Materials 2026, 19(8), 1569; https://doi.org/10.3390/ma19081569 - 14 Apr 2026
Viewed by 555
Abstract
In this work, we demonstrate that both carbon nanotubes (CNT) and graphene nanosheets (G) were successfully modified by π-stacking interactions with a pyrene derivative (PY), yielding the functionalized nanofillers CNT-PY and G-PY, which were subsequently dispersed within an aeronautical epoxy matrix. This functionalization [...] Read more.
In this work, we demonstrate that both carbon nanotubes (CNT) and graphene nanosheets (G) were successfully modified by π-stacking interactions with a pyrene derivative (PY), yielding the functionalized nanofillers CNT-PY and G-PY, which were subsequently dispersed within an aeronautical epoxy matrix. This functionalization is highly effective in preserving the remarkable electronic properties of carbon nanotubes and graphene nanosheets. At the same time, the non-covalent functionalization reduces the resin viscosity, enabling a more effective dispersion of the nanofillers. This results in improved rheological behavior and an overall enhancement of the structural performance of the nanocomposites compared to the resin containing unfunctionalized carbon nanofillers (CNT and G). Additional improvements are also observed in electrical properties, self-healing efficiency, and thermal stability. In particular, the samples containing functionalized carbon nanotubes (TBD + 1%CNT-PY) and functionalized graphene nanosheets (TBD + 1%G-PY) exhibit higher conductivities—0.391 S/m and 0.1 S/m, respectively—than the samples loaded with unfunctionalized carbon nanotubes (TBD + 1%CNT) and unfunctionalized graphene nanosheets (TBD + 1%G), which show conductivity values of 0.292 S/m and 4.82 × 10−3 S/m, respectively. The functionalized graphene nanosheets (G-PY) display significantly greater thermal stability, with degradation temperatures reaching 670 °C, compared to 310 °C for unfunctionalized ones (G). The functionalized carbon nanotubes (CNT-PY) show a 10% weight loss at 520 °C due to the degradation of the pyrene groups. Significant improvements in the final properties can be achieved when carbon-based nanofillers are homogeneously dispersed in the matrix and the external load is efficiently transferred through strong filler–polymer interfacial interactions, leading to composites with superior characteristics suitable for advanced applications. Tunneling Atomic Force Microscopy (TUNA) highlights the morphological features of the two types of carbon nanofillers, their dispersion within the polymer matrix and the effect of the functionalization on the electrical pathways and conductivity of the samples at both the micro- and nanometer-scale. The measured electrical conductivities are consistent with the electric currents detected at the micro/nanoscale. Full article
(This article belongs to the Special Issue Advanced Resin Composites: From Synthesis to Application)
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15 pages, 1827 KB  
Article
C16-Functionalized Diatomaceous Earth: A Sustainable Approach for the Selective Encapsulation and Remediation of Hydrocarbons from Water
by Rosalia Maria Cigala, Mario Samperi, Paola Cardiano, Alessandro Tripodo, Giuseppe Sabatino, Catia Cannilla, Giuseppina La Ganga and Ileana Ielo
Materials 2026, 19(8), 1529; https://doi.org/10.3390/ma19081529 - 10 Apr 2026
Cited by 1 | Viewed by 681
Abstract
The primary objective of this research is to engineer a high-performance, sustainable material for aquatic remediation by repurposing low-cost biogenic silica into a selective hydrophobic adsorbent. By integrating the natural hierarchical porosity of Diatomaceous Earth (DE) with a tailored silanization strategy, this work [...] Read more.
The primary objective of this research is to engineer a high-performance, sustainable material for aquatic remediation by repurposing low-cost biogenic silica into a selective hydrophobic adsorbent. By integrating the natural hierarchical porosity of Diatomaceous Earth (DE) with a tailored silanization strategy, this work aims to provide a scalable and eco-friendly solution for the efficient encapsulation and mechanical recovery of hydrocarbons from contaminated water. To overcome the inherent hydrophilicity of DE, a two-step functionalization process was developed, involving alkaline activation followed by the covalent grafting of hexadecyltrimethoxysilane (C16) in different concentrations. The resulting C16@DE hybrid materials underwent a dramatic surface energy transformation, shifting from hydrophilic behavior to robust hydrophobicity, with static contact angles reaching up to 134.8°. Optical analysis revealed a unique remediation mechanism: while pristine DE disperses homogeneously in the aqueous phase, functionalized C16@DE spontaneously organizes into discrete pellets upon contact with diesel, effectively encapsulating the fuel. Quantitative UV/vis spectrophotometry confirmed that these composites sequester approximately 55–56% of the diesel phase. Together, these results demonstrate that C16@DE materials couple intrinsic biosilica porosity with tailored hydrophobicity to achieve efficient hydrocarbon capture. By combining the natural hierarchical porosity of diatoms with engineered surface selectivity, this research positions functionalized DE as a scalable, low-cost, and eco-friendly promising solution for marine oil spill recovery and industrial wastewater treatment. Full article
(This article belongs to the Section Green Materials)
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15 pages, 1310 KB  
Article
Redox Mechanisms of Silica-Supported Ni Particles: An X-Ray Absorption Fine Structure Investigation
by Eka Novitasari, Kodai Ohta, Asaka Azuma, Yasuhiro Niwa, Masao Kimura and Yasuhiro Inada
Materials 2026, 19(8), 1509; https://doi.org/10.3390/ma19081509 - 9 Apr 2026
Viewed by 500
Abstract
The redox mechanisms of silica-supported Ni particles were investigated using their in situ X-ray absorption fine structure, providing mechanistic insights into partially reduced NiO and partially oxidized metallic Ni. The results of surface oxidation of partially reduced NiO particles at room temperature revealed [...] Read more.
The redox mechanisms of silica-supported Ni particles were investigated using their in situ X-ray absorption fine structure, providing mechanistic insights into partially reduced NiO and partially oxidized metallic Ni. The results of surface oxidation of partially reduced NiO particles at room temperature revealed that the surface was not fully covered with metallic Ni and that metallic Ni had also formed within the particle interior. During NiO particle reduction, the process initiates at specific surface sites, and before the metallic Ni phase fully covers the surface, O2− ions are expelled from the particle. Conversely, the oxidation of metallic Ni particles progresses inward from the surface, with an accompanying increase in the thickness of the NiO layer that forms upon O2 exposure at room temperature. This mechanism is supported by observations that the reduction of a thin NiO shell on metallic Ni particles was completed below 200 °C, while reduction temperatures shifted to higher values as the NiO layer thickness increased. The distinct oxidation and reduction mechanisms are attributed to differences in the migration direction of O2− ions. During reduction, it is proposed that O2− ions within the particles migrate to the surface along the interface between the NiO phase and the metallic Ni phase. This study elucidates the detailed mechanism behind the redox interconversion between NiO and metallic Ni in solid catalyst particles. Full article
(This article belongs to the Section Catalytic Materials)
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23 pages, 758 KB  
Article
Element-Free Galerkin Method for Analyzing Size-Dependent Thermally Induced Free Vibration Characteristics of Functionally Graded Magneto-Electro-Elastic Doubly Curved Microscale Shells
by Chih-Ping Wu and Meng-Jung Liu
Materials 2026, 19(8), 1494; https://doi.org/10.3390/ma19081494 - 8 Apr 2026
Cited by 1 | Viewed by 363
Abstract
Within the framework of consistent couple stress theory (CCST) and employing Hamilton’s principle, we derive a Galerkin weak formulation to analyze the three-dimensional (3D) size-dependent free vibration characteristics of a simply supported, functionally graded (FG) magneto-electro-elastic (MEE) doubly curved (DC) microscale shell subjected [...] Read more.
Within the framework of consistent couple stress theory (CCST) and employing Hamilton’s principle, we derive a Galerkin weak formulation to analyze the three-dimensional (3D) size-dependent free vibration characteristics of a simply supported, functionally graded (FG) magneto-electro-elastic (MEE) doubly curved (DC) microscale shell subjected to a uniform temperature change. Incorporating the differential reproducing kernel (DRK) interpolants into the weak formulation, we further develop an element-free Galerkin (EFG) method. The microscale shell of interest is composed of two-phase MEE materials, and its material properties are assumed to vary through its thickness according to a power-law distribution of the volume fractions of the constituents. The results show that the natural frequency solutions obtained using the EFG method are in excellent agreement with the reported 3D solutions for laminated composite and FG-MEE macroscale plates, with the material length-scale parameter and the inverse of the curvature radii set to zero. The effects of the material length-scale parameter, temperature change, inhomogeneity index, and mid-surface radius and length-to-thickness ratios on the FG-MEE microscale shell’s free vibration characteristics in a thermal environment are examined and appear to be significant. Full article
(This article belongs to the Special Issue Mechanical Properties of Engineering Materials and Their Evaluation Methods)
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12 pages, 418 KB  
Article
Mechanical Properties of Composite Core Build-Up Materials: A Comparative Study
by Emily Mundy, Sanaya V. Engineer, Sheila Butler, Amin Rizkalla, Gildo Coelho Santos Junior and Maria Jacinta Moraes Coelho Santos
Materials 2026, 19(8), 1487; https://doi.org/10.3390/ma19081487 - 8 Apr 2026
Viewed by 607
Abstract
Objective: To determine the most suitable core build-up materials based on their mechanical and physical properties, different resin based materials were evaluated for flexural strength (FS), flexural modulus (E), modulus of resilience (R), water sorption (WS), and solubility (SO). Materials and Methods: Three [...] Read more.
Objective: To determine the most suitable core build-up materials based on their mechanical and physical properties, different resin based materials were evaluated for flexural strength (FS), flexural modulus (E), modulus of resilience (R), water sorption (WS), and solubility (SO). Materials and Methods: Three dual-cure resins (CosmeCore DC Automix, CCC; Clearfil DC Core Plus, CCP; MultiCore Flow, CMC) and two bulk fill composites (Filtek One Bulk Fill Restorative, BFO; Filtek Bulk Fill Flowable, BFF) were tested, with Filtek Supreme Ultra (FSU) as the control. All tests followed ISO 4049. Beam specimens (25 × 2 × 2 mm, n = 12) were used to determine FS and E after 24 h storage in 37 °C deionized water, using a three-point bending test. Disc specimens (15 × 1 mm, n = 5) were used for WS and SO by measuring mass changes before and after water storage. Data were analysed using one way ANOVA and Tukey post hoc tests (p < 0.05). Results: CCC exhibited the highest FS and lowest WS. BFF showed the lowest E, while BFO exhibited the highest R. FSU demonstrated the lowest FS and R, along with the highest WS. No significant differences in SO were observed among groups. Conclusions: The evaluated materials showed considerable variation in mechanical and physical properties. CCC and BFO demonstrated the most favourable performance, suggesting they are the most suitable candidates for core build up procedures among the materials tested. Full article
(This article belongs to the Section Advanced Composites)
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20 pages, 2242 KB  
Article
Influence of Catalyst Composition on the Acidic Oxygen Evolution Reaction: From Single Oxide IrO2 to High-Entropy Oxide IrNiMnFeCoCuVOx
by Miguel Sánchez Martín, Miriam Alonso Menéndez, Daniel Barreda, Ricardo Santamaría, Clara Blanco, Victoria G. Rocha and Jonathan Ruiz Esquius
Materials 2026, 19(7), 1402; https://doi.org/10.3390/ma19071402 - 31 Mar 2026
Viewed by 730
Abstract
Developing active and robust catalysts for the acidic oxygen evolution reaction (OER) with reduced Ir loading is still a challenge in the industrial production of green H2. In this work, several catalysts ranging from single metal oxides (e.g., IrO2) [...] Read more.
Developing active and robust catalysts for the acidic oxygen evolution reaction (OER) with reduced Ir loading is still a challenge in the industrial production of green H2. In this work, several catalysts ranging from single metal oxides (e.g., IrO2) to high-entropy oxides (IrNiMnFeCoCuVOx) were synthesised through thermal decomposition in air to study the effect of the mixed-oxide composition in terms of activity and stability towards the acidic OER. Catalysts were named MOx-n, with n being the number of metal elements in the mixture. The results show that the activity of rutile IrO2 can be improved by introducing other elements into the composition. The best performance was obtained for MOx-4 to MOx-5, which delivered a current density of 10 mA cm−2 at an overpotential (η10) of 279 ± 4 mV; approx. 100 mV lower than IrO2 at a comparable Ir loading and with better stability. Nevertheless, further increasing the complexity of the mixed oxide resulted in an evident degradation in terms of activity and stability. It is worth noting that surface dissolution and reconstruction occurred with all mixed-oxide catalysts, including high-entropy configurations. Full article
(This article belongs to the Special Issue Application of Electrocatalytic and Electrochemical Materials in Energy)
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16 pages, 7407 KB  
Article
Anomalous Paramagnetic Meissner-like AC Response in EuRbFe4As4 Superconductor
by Adrian Crisan, Alina M. Badea, Ion Ivan, Corneliu F. Miclea, Daniel N. Crisan, Armando Galluzzi and Massimiliano Polichetti
Materials 2026, 19(7), 1365; https://doi.org/10.3390/ma19071365 - 30 Mar 2026
Viewed by 458
Abstract
Magnetic superconductor EuRbFe4As4 is a quite unique system in which macroscopic superconductivity and magnetic ordering coexist, with interesting interactions between Abrikosov vortices and Eu2+ spins that were investigated mostly by static (DC) magnetization measurements. Our aim is to study [...] Read more.
Magnetic superconductor EuRbFe4As4 is a quite unique system in which macroscopic superconductivity and magnetic ordering coexist, with interesting interactions between Abrikosov vortices and Eu2+ spins that were investigated mostly by static (DC) magnetization measurements. Our aim is to study the dynamic interactions between the two sub-systems using AC susceptibility measurements in a wide range of temperatures and superimposed DC fields. In low DC fields, the magnetic transition at 15 K is clearly visible. We have observed very little difference between the AC susceptibility in different cooling regimes, but large difference for different field orientation. For field perpendicular to the superconducting planes, we have observed an anomalous dependence just below the critical temperature, which is absent in the parallel field orientation. We explained the anomaly by the interplay between the sample dimensions and the temperature dependence of the London penetration depth which may allow the paramagnetic Meissner-like response to be detected in the temperature dependence of the AC susceptibility. We stress that the newly reported phenomenon reflects an AC-susceptibility manifestation of a field-stabilized critical state rather than a thermodynamic phase. In addition, we have observed a paramagnetic AC response in the normal phase, in both field orientations, indicative of interactions between Eu2+ spins and flux lines. Full article
(This article belongs to the Special Issue Copper- and Iron-Based Superconductors: Preparation, Properties, and Functionalization Applications)
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17 pages, 6088 KB  
Article
Visualizing the 3D Evolution and Morphology of Hydrogen-Assisted Ductile Crack Growth in Hydrogen-Precharged P355NH Steel Using X-Ray Micro-Computed Tomography
by Alexander Hell, Jonas Fell, Torben Werning and Hans-Georg Herrmann
Materials 2026, 19(7), 1335; https://doi.org/10.3390/ma19071335 - 27 Mar 2026
Viewed by 561
Abstract
Hydrogen embrittlement is known to adversely affect the mechanical properties of low-carbon steels used for pipelines and pressure vessels, leading to accelerated crack growth and lowered fracture toughness. To overcome the limitations of surface-based analysis, this study employs X-ray micro-computed tomography (µ-CT) to [...] Read more.
Hydrogen embrittlement is known to adversely affect the mechanical properties of low-carbon steels used for pipelines and pressure vessels, leading to accelerated crack growth and lowered fracture toughness. To overcome the limitations of surface-based analysis, this study employs X-ray micro-computed tomography (µ-CT) to provide a comprehensive 3D evaluation of the crack evolution. This approach is used to assess hydrogen-assisted crack growth in P355NH compact tension samples from previous fracture mechanical tests and enables a precise quantification of the internal crack path and the crack tip opening angle (CTOA) across the entire specimen thickness as well as the local damage morphology. By integrating these spatial parameters, a deeper understanding of the impact of hydrogen on local fracture mechanisms is achieved, revealing insights that have remained hidden in previous two-dimensional microscopy observations. For instance, µ-CT results clearly demonstrate that the hydrogen-assisted crack propagation is associated with increased void formation and secondary cracking in vicinity of the crack tip. However, it is proposed that the results are superimposed with continuous hydrogen desorption, which implies a need for in situ charging during mechanical loading and an analysis of the hydrogen concentration profile. Both will be the scope of further studies. Full article
(This article belongs to the Section Mechanics of Materials)
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27 pages, 4691 KB  
Article
Material Nondestructive Investigations Reveal the Hidden Secrets of Two Saxon Quarter Thalers Issued in 1544—A Case Study
by Marzena Grochowska-Jasnos, Emanoil Pripon, Lucian Barbu Tudoran, Nicoleta Ignat, Gheorghe Borodi and Ioan Petean
Materials 2026, 19(7), 1325; https://doi.org/10.3390/ma19071325 - 26 Mar 2026
Viewed by 685
Abstract
Saxony was ruled by two cousins in 1544: John Frederick I (Elector of Saxony) and his cousin Maurice (Duke of Saxony). Both rulers’ names appear on each side of the quarter thalers produced in this year. They were enemies involved in religious wars, [...] Read more.
Saxony was ruled by two cousins in 1544: John Frederick I (Elector of Saxony) and his cousin Maurice (Duke of Saxony). Both rulers’ names appear on each side of the quarter thalers produced in this year. They were enemies involved in religious wars, although they were both Protestants. Two types of quarter thalers from 1544 occur: a pierced random find from Transylvania (Romania) with four shields on the reverse, heavily worn, and another one with three shields on the obverse side, found in the Głogów Hoard (Poland), which is well preserved. Why did they issue two types in the same year? Was it a matter of silver title or other historical factors? Nondestructive investigation methods were used: XRD revealed the phases within the alloy and patina layer; SEM-EDS revealed the morphological aspects and their elemental compositions, which were correlated with XRF results. The results show that both coins have closer silver amounts, from 91 to 96 wt.%. The EDS results were in good agreement with the XRF results. Lead traces indicated a difference between them: the four-shielded coin is lead-free, while the three-shielded coin has a moderate amount of lead, about 0.5 wt.%. The archeological data evidence that the four-shielded coin issued in 1544 is rarer than the three-shielded one because it was issued during specific historical conditions. Black patina is formed by a mixture rich in copper oxides mixed with silver oxides and Ag2S. The presence of silver sulfide in the patina layer confirms that the pierced coin was in prolonged contact with the skin surface. Also, the finest traces of minerals embedded in the patina layer (e.g., quartz, kaolinite, and calcite) suggest that they were embedded in the patina via prolonged exposure to particulate matter. The mineral inclusions in the patina would have been more numerous if they were formed underground. Thus, the pierced four-shielded coin was probably worn as jewelry by nomads, while the three-shielded coin was most likely treasured in a well-preserved hoard. Full article
(This article belongs to the Special Issue Non-Destructive Testing of Materials and Parts: Techniques, Case Studies and Practical Applications—2nd Edition)
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20 pages, 2556 KB  
Article
Variability of Properties of Wood Biomass Combustion Waste During the Heating Season in the Context of Their Environmental Use
by Elżbieta Rolka, Anna Skorwider-Namiotko and Radosław Szostek
Materials 2026, 19(7), 1295; https://doi.org/10.3390/ma19071295 - 25 Mar 2026
Viewed by 585
Abstract
The use of wood chips in the heating sector leads to the generation of combustion waste with variable properties, which poses challenges for their rational management. To determine the variability of combustion waste, samples were collected over a 13-week period during the heating [...] Read more.
The use of wood chips in the heating sector leads to the generation of combustion waste with variable properties, which poses challenges for their rational management. To determine the variability of combustion waste, samples were collected over a 13-week period during the heating season, as weekly aggregate samples from a biomass bioheating plant burning wood chips. Three waste fractions were obtained for analysis: residue from the grate (B1), dust from the dust collector (B2), and boiler dust (B3). Dry matter (DM), reaction (pHKCl), electrolytic conductivity (EC), content of total carbon (TC), total nitrogen (TN), macronutrients (P, K, Mg, Ca, Na), and heavy metals (Fe, Mn, Zn, Cu, Pb, Cd, Cr, Co, Ni) were determined in the collected samples. All waste fractions were characterized by an alkaline reaction. Regardless of the waste fraction, the macronutrient content was dominated by Ca, K, and Mg, with significantly lower levels of P and Na. Among heavy metals, Fe, Mn, and Zn had the highest recorded contents, and the lowest by far was Cd. With respect to sampling dates, the least diversified chemical composition was observed for B1 samples, more diversified for B2, and the most diversified for B3. In turn, regardless of the waste fraction, the most diversified results were observed for Cd and Pb, and the least for pH, DM, and TC. Concerning environmental management of combustion waste, fraction B1 deserves attention, as it was characterized by the richest chemical composition (TN, P, K, Mg, Ca, Na, Mn, Zn, Cu, Co, Ni). However, due to the highest content of undesirable heavy metals (Pb, Cd) and the highest salinity, it requires constant monitoring of the composition. Full article
(This article belongs to the Special Issue Biomass-Derived Carbon and Non-Biomass Industrial Wastes for High-Value Functional Materials)
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24 pages, 3043 KB  
Article
Friction-Induced Thermal Effects in an FGM Layer in Contact with a Homogeneous Layer
by Katarzyna Topczewska
Materials 2026, 19(7), 1299; https://doi.org/10.3390/ma19071299 - 25 Mar 2026
Cited by 1 | Viewed by 365
Abstract
An analytical model of frictional heat transfer during the uniform sliding of two layers is proposed. One layer is composed of a functionally graded material (FGM) with a thermal conductivity coefficient that varies exponentially across its thickness, while the second layer is homogeneous, [...] Read more.
An analytical model of frictional heat transfer during the uniform sliding of two layers is proposed. One layer is composed of a functionally graded material (FGM) with a thermal conductivity coefficient that varies exponentially across its thickness, while the second layer is homogeneous, with constant thermophysical properties. The thermal problem of friction is formulated as an initial boundary value problem of heat conduction, accounting for the thermal contact conductance and convective heat exchange with the environment. An exact solution for constant friction power was obtained using the Laplace integral transform, supplemented by an asymptotic form for the initial stage of heating. Based on these analytical solutions, a comprehensive study was carried out for a frictional system comprising a ceramic–metal FGM composite in contact with a homogeneous friction material. A dimensional analysis allowed for both a qualitative and quantitative investigation into the influence of contact conductance, convective heat exchange, layer thickness and the FGM gradient parameter on the temperature evolution and distribution, as well as the time to reach the steady state. It was demonstrated that the implementation of an appropriately graded material can substantially improve thermal operating conditions by enhancing heat dissipation into the material bulk and intensifying convective cooling. Full article
(This article belongs to the Special Issue Use of Modern Materials in Technological Processes Accompanied by Frictional Heating (3rd Edition))
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13 pages, 1894 KB  
Article
Circular Approach to Composite Materials: Synthesis of Carbon Nanomaterials from Polymer Recycling Liquid By-Products
by Evangelos Tsimis, Stefania Termine, Maria Modestou, Aikaterini-Flora Trompeta, Szymon Sobek, Marcin Sajdak, Jakub Adamek, Sebastian Werle and Costas Charitidis
Materials 2026, 19(6), 1266; https://doi.org/10.3390/ma19061266 - 23 Mar 2026
Viewed by 644
Abstract
The growing volume of fiber-reinforced polymer composite waste creates an urgent need for efficient recycling technologies. While solvolysis effectively breaks down thermoset matrices for fiber reinforcement recovery, the process generates hydrocarbon-rich liquid by-products that require further management. This study validates the use of [...] Read more.
The growing volume of fiber-reinforced polymer composite waste creates an urgent need for efficient recycling technologies. While solvolysis effectively breaks down thermoset matrices for fiber reinforcement recovery, the process generates hydrocarbon-rich liquid by-products that require further management. This study validates the use of these liquid recycling streams—derived from the solvolysis of unsaturated polyester and epoxy resins—as sustainable carbon precursors for the growth of carbon nanomaterials. Synthesis was performed via catalytic chemical vapor deposition (CVD) at 850 °C using iron nanoparticles impregnated on a zeolite substrate. Morphological analysis confirmed the production of one-dimensional nanostructures (carbon nanotubes/nanofibers), with average diameters below 100 nm. Raman spectroscopy revealed a high degree of graphitization, with ID/IG ratios ranging from 0.25 to 0.58, which is comparable to structures synthesized from conventional precursors. Thermogravimetric analysis (TGA) demonstrated high thermal stability and carbon purity reaching up to 90.3%. These findings demonstrate a viable upcycling pathway that enhances the economic attractiveness of composite recycling by transforming waste into advanced nanomaterials. Full article
(This article belongs to the Special Issue Carbonaceous Materials: Fabrication, Characterization and Applications—Second Edition)
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21 pages, 1471 KB  
Article
Characterisation of Scale Deposits in Drinking Water Pipes by FTIR and ICP-OES
by Paweł Wiercik, Justyna Stańczyk and Justyna Możejko
Materials 2026, 19(6), 1223; https://doi.org/10.3390/ma19061223 - 20 Mar 2026
Viewed by 636
Abstract
Attenuated Total Reflection–Fourier Transform Infrared (ATR-FTIR) spectroscopy and Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) are widely used to investigate the chemical structure and elemental composition of materials. However, the combined application of both methods to examine scale deposits in the water supply network [...] Read more.
Attenuated Total Reflection–Fourier Transform Infrared (ATR-FTIR) spectroscopy and Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) are widely used to investigate the chemical structure and elemental composition of materials. However, the combined application of both methods to examine scale deposits in the water supply network has not yet been explored. In this study, scale deposits collected from the inlets of six pipes (steel, cast iron, lead, wooden) were analysed using both techniques. The application of ATR-FTIR and ICP-OES enabled the identification of mineral phases, organics, and structural differences between individual scale layers. Iron oxyhydroxides, together with silica and aluminosilicates, dominated most samples, whereas shower faucet deposit was primarily composed of carbonates and stearates. The combined analytical approach helped to avoid misinterpretation of FTIR data: although the spectrum of lead pipe deposit resembled hydrated lead carbonates, ICP-OES revealed only trace amounts of lead. Differences in crystallinity between successive layers allowed the reconstruction of the deposition process within the pipes. Poorly crystalline iron oxyhydroxides and silica occurred near pipe walls, while more crystalline phases developed closer to the water interface. These results demonstrate that combining ATR-FTIR and ICP-OES provides a reliable framework for interpreting scale deposit composition and formation in water distribution systems. Full article
(This article belongs to the Section Advanced Materials Characterization)
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9 pages, 904 KB  
Perspective
The Lithium-Ion Battery Recycling Trilemma: Bridging the Gap Between Material Science, Economic Reality, and Regulatory Policy
by Qi Zhang
Materials 2026, 19(6), 1235; https://doi.org/10.3390/ma19061235 - 20 Mar 2026
Viewed by 803
Abstract
The electric vehicle revolution has created an urgent need for lithium-ion battery (LIB) recycling, with projections exceeding 11 million tons of end-of-life batteries annually by 2030. However, progress toward a circular economy remains fragmented. This perspective article introduces the concept of a ‘Recycling [...] Read more.
The electric vehicle revolution has created an urgent need for lithium-ion battery (LIB) recycling, with projections exceeding 11 million tons of end-of-life batteries annually by 2030. However, progress toward a circular economy remains fragmented. This perspective article introduces the concept of a ‘Recycling Trilemma,’ arguing that technological advancements in material separation are systematically undermined by economic volatility and regulatory fragmentation. While current literature focuses on isolated domains—chemistry, business models, or policy—this work provides a systems-level synthesis. By analyzing the friction points between material science (e.g., binder removal, impurity sensitivity), economic realities (e.g., logistics costs, LFP profitability), and regulatory frameworks (e.g., EU vs. US divergence), we propose that true circularity requires synchronized design-for-recycling, market stabilization mechanisms, and harmonized digital product passports. The paper concludes that overcoming the trilemma demands a shift from isolated fixes to integrated, cross-sectoral coordination. Full article
(This article belongs to the Special Issue Recycling and Electrode Materials of Lithium Batteries)
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23 pages, 10058 KB  
Article
Advanced Manufacturing of PLA Surgical Templates for Orbital Floor Geometry: Optimizing Fidelity and Surface Morphology via Variable Layer Height MEX 3D Printing
by Paweł Turek, Grzegorz Budzik, Łukasz Przeszłowski, Anna Bazan, Bogumił Lewandowski, Paweł Pakla, Tomasz Dziubek, Robert Brodowski, Małgorzata Zaborniak, Jan Frańczak and Michał Bałuszyński
Materials 2026, 19(6), 1208; https://doi.org/10.3390/ma19061208 - 19 Mar 2026
Viewed by 523
Abstract
Precise orbital floor reconstruction requires personalised surgical templates that combine high geometric fidelity with manufacturing efficiency. This study presents and validates the TARMM procedure, developed to optimise the production of polylactide (PLA) templates. A key innovation is the integration of advanced machine learning [...] Read more.
Precise orbital floor reconstruction requires personalised surgical templates that combine high geometric fidelity with manufacturing efficiency. This study presents and validates the TARMM procedure, developed to optimise the production of polylactide (PLA) templates. A key innovation is the integration of advanced machine learning algorithms (Random Forest) and Mitchell–Netravali interpolation to reduce medical reconstruction artefacts, as well as the implementation of Material Extrusion (MEX) technology with Variable Layer Height (VLH). This strategy minimises the stair-step effect on complex anatomical curvatures while maintaining high process throughput. The results demonstrate that the TARMM procedure ensures a geometric error within ±0.1 mm. A strong linear correlation (r = 0.99) was found between layer height and surface roughness (Sa), indicating that a 0.07 mm layer in critical areas significantly improves template morphology and facilitates the contouring of titanium meshes. The clinical validation across 21 cases confirmed a 30 min reduction in surgical preparation time. The developed method serves as a low-cost, high-precision alternative to photopolymerization technologies, contributing to modern 3D printing applications in maxillofacial surgery. Full article
(This article belongs to the Special Issue Advances in 3D Printing Technologies: Design, Manufacturing, and Applications)
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20 pages, 1665 KB  
Review
Bio-Based and Sustainable Alternatives to Conventional and Synthetic Leather
by Ewa Oleksińska-Merida, Michał Puchalski and Lucyna Herczyńska
Materials 2026, 19(6), 1198; https://doi.org/10.3390/ma19061198 - 18 Mar 2026
Cited by 1 | Viewed by 2746
Abstract
Growing demand for sustainable materials has intensified research into eco-friendly alternatives to conventional and synthetic leathers. Traditional bovine leather and its chromium-tanning process heavily contribute to water pollution, toxic waste generation, and carbon emissions, while synthetic leather derived from Polyvinyl Chloride (PVC) and [...] Read more.
Growing demand for sustainable materials has intensified research into eco-friendly alternatives to conventional and synthetic leathers. Traditional bovine leather and its chromium-tanning process heavily contribute to water pollution, toxic waste generation, and carbon emissions, while synthetic leather derived from Polyvinyl Chloride (PVC) and polyurethane (PU) presents challenges related to fossil fuel dependence and non-biodegradability. This review explores bio-based and sustainable leather substitutes that are made of plants, microbial cellulose, and mycelium fungi. Plant-based leather substitutes such as Vegea®, Desserto®, and Piñatex® use agricultural waste products to create durable, partially biodegradable composites. Microbial cellulose from kombucha fermentation offers material with good physical and aesthetic properties. Mycelium leather, derived from fungal biomass, demonstrates potential for scalable and low-impact production. Comparative analyses of mechanical and physical properties show that mycelium composites are approaching industrial standards, though challenges remain regarding tensile strength, water resistance, and process standardization. Despite current limitations, bio-based leathers, particularly mycelium composites, offer a promising way toward circular material innovation and carbon-neutral manufacturing in fashion, automotive, design and other industries. Full article
(This article belongs to the Section Green Materials)
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16 pages, 22264 KB  
Article
High-Resolution Depth Profiling of Residual Stresses in PVD Coatings on Additively Manufactured Polymers via FIB-DIC and Eigenstrain Theory
by José Daniel Rodríguez-Mariscal, Karuna Srivastava, Ismael Romero-Ocaña, Ramón Escobar-Galindo, Andrea Bernasconi and Jesús Hernández-Saz
Materials 2026, 19(6), 1171; https://doi.org/10.3390/ma19061171 - 17 Mar 2026
Viewed by 610
Abstract
The synergy between additively manufactured (AM) polymers and functional PVD coatings is crucial for advanced applications, yet the reliability of these hybrid systems is dictated by the residual stresses induced during deposition. This work presents the first in-depth, nanoscale profiling of residual stresses [...] Read more.
The synergy between additively manufactured (AM) polymers and functional PVD coatings is crucial for advanced applications, yet the reliability of these hybrid systems is dictated by the residual stresses induced during deposition. This work presents the first in-depth, nanoscale profiling of residual stresses in Ti6Al4V and SS316 coatings on 3D-printed Acrylonitrile Styrene Acrylate (ASA) and Silicon (Si) substrates. A cutting-edge methodology combining Focused Ion Beam (FIB) milling with Digital Image Correlation (DIC), rigorously interpreted through the non-integral eigenstrain theory, is employed. Our findings reveal a consistent pattern of compressive stresses near the coating surface but expose a significant tensile stress peak at the coating-substrate interface, a feature not observed on reference silicon substrates. High-resolution electron microscopy and elemental analysis suggest that this stress concentration is associated with the presence of a thin, brittle oxide interlayer formed on the substrate surface. Furthermore, this study quantifies the dominant effect of the low-stiffness polymer substrate, which leads to a strain relief magnitude an order of magnitude higher than in rigid substrates. This work provides critical quantitative data on the failure-driving mechanisms in these emerging material systems and establishes a robust, optimized metrological protocol for their characterization. Full article
(This article belongs to the Section Mechanics of Materials)
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12 pages, 2276 KB  
Article
Electrical Potential and Cell Immobilisation Capacity of a Laser-Treated Titanium Alloy Surface
by Arturs Abolins, Alberta Aversa, Yuri Dekhtyar, Maris Dortins, Marks Gorohovs, Galina Khroustalyova, Lyubomir Lazov, Arturs Mamajevs, Mohammed Awad Hassan Olaish, Aleksander Rapoport, Elizabete Skrebele, Hermanis Sorokins and Edmunds Sprudzs
Materials 2026, 19(6), 1051; https://doi.org/10.3390/ma19061051 - 10 Mar 2026
Cited by 1 | Viewed by 424
Abstract
Titanium and its alloys are widely used in endoprostheses. The naturally formed titanium dioxide film on titanium surfaces improves chemical stability and enhances implant biocompatibility. However, oxidised titanium surfaces may also promote bacterial adhesion and biofilm formation, contributing to implant-associated infections. Therefore, surface [...] Read more.
Titanium and its alloys are widely used in endoprostheses. The naturally formed titanium dioxide film on titanium surfaces improves chemical stability and enhances implant biocompatibility. However, oxidised titanium surfaces may also promote bacterial adhesion and biofilm formation, contributing to implant-associated infections. Therefore, surface modification represents a key strategy for controlling microbial–implant interactions. This article focuses widely used titanium alloy Ti-6Al-4V treated with a laser beam, which induces surface colour changes as a result of oxide formation. Laser processing enables controlled formation of micro- and nanoscale features, structural reconstructions, and defects that may influence the surface electrical charge and, consequently, cell immobilisation. Thus, the surface colour, electrical potential, and cell immobilisation capacity are likely interrelated. From a manufacturing perspective, titanium oxide colouring facilitates quality control and process reproducibility, as surface colour provides a rapid, non-destructive visual indicator of oxide thickness and treatment consistency. This study aims to identify correlations among surface colour, electrical potential, and cell immobilisation capacity on laser-treated titanium alloys. A relationship between the optical properties, electronic structure, and biological response of laser-processed titanium oxide films is established. Specifically, the blue colour saturation of the oxide film is inversely correlated with the electron work function. A more saturated blue corresponds to a lower work function, indicating a higher positive surface charge density. This shift is attributed to changes in electron affinity, likely resulting from laser-induced structural reconstruction and defect formation within the oxide layer. The proposed changes in electronic structure are supported by modifications in the electronic density of states, analysed using near-threshold photoelectron spectroscopy. The biological response is directly linked to these physical changes: enhanced immobilisation of yeast (Saccharomyces cerevisiae) cells on the treated alloy surface correlates with the electron work function. These results may assist in the development of controlled titanium oxide surfaces with enhanced biocompatibility. Full article
(This article belongs to the Special Issue Advances in Plasma and Laser Engineering (Third Edition))
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12 pages, 3959 KB  
Article
Effect of Prior Austenite Grain Size on the Hydrogen Diffusion Behavior in 30MnB5 Steel
by Hyunbin Nam, Minseok Seo and Cheolho Park
Materials 2026, 19(5), 940; https://doi.org/10.3390/ma19050940 - 28 Feb 2026
Viewed by 502
Abstract
In this study, we investigated the effect of heat treatment-induced grain size on the hydrogen embrittlement (HE) resistance of 30MnB5 steel, focusing particularly on the variation in prior austenite grain (PAG) size. As the heat treatment time increased, the PAGs coarsened, leading the [...] Read more.
In this study, we investigated the effect of heat treatment-induced grain size on the hydrogen embrittlement (HE) resistance of 30MnB5 steel, focusing particularly on the variation in prior austenite grain (PAG) size. As the heat treatment time increased, the PAGs coarsened, leading the martensite packets, blocks, and lath sizes to also coarsen. As the microstructure became more refined, the boundary density of the packet–block–lath structure increased along with a significant increase in the low-angle grain boundary (LAGB) fraction. The microstructure refinement accelerated the initial permeation rate of hydrogen, while the high density of LAGBs and trap sites effectively suppressed its long-term diffusion/localization. The slow strain rate tensile test confirmed that the tensile strength and elongation of 30MnB5 steel in a hydrogen environment were lower than those in air, indicating HE. Furthermore, the results showed that the HE sensitivity decreased in the fine microstructure condition, as evidenced by the smaller reduction in elongation compared to the coarse microstructure. The study results will enhance the understanding of hydrogen-induced degradation in hot-stamped automotive steels and offer fundamental insights for optimizing heat treatment strategies applied to 30MnB5 steel for mitigating HE. Full article
(This article belongs to the Special Issue Welding and Joining Technologies for Advanced Structural Alloys and Multifunctional Materials)
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32 pages, 2048 KB  
Review
Biocompatible Thin Films Deposited by Laser Techniques
by Andrei Teodor Matei and Anita Ioana Visan
Materials 2026, 19(5), 925; https://doi.org/10.3390/ma19050925 - 28 Feb 2026
Viewed by 651
Abstract
Biocompatible thin films are essential for advancing biomedical devices, as they enhance integration with biological tissues, improve device longevity, and reduce complications. The rapid evolution of both medical needs and materials science has led to a diverse array of deposition techniques, each offering [...] Read more.
Biocompatible thin films are essential for advancing biomedical devices, as they enhance integration with biological tissues, improve device longevity, and reduce complications. The rapid evolution of both medical needs and materials science has led to a diverse array of deposition techniques, each offering unique advantages and challenges for tailoring surface properties without compromising the bulk characteristics of implants and sensors. While laser-based methods—such as pulsed laser deposition (PLD) and Matrix-Assisted Pulsed Laser Evaporation (MAPLE)—are renowned for their precision, ability to preserve complex material stoichiometry, and suitability for low-temperature processing, the broader landscape includes several other important approaches. Physical Vapor Deposition (PVD) techniques, including magnetron sputtering and pulsed electron deposition, are widely used for their ability to create uniform, adherent coatings with controlled thickness and composition, making them suitable for both hard and soft biomedical substrates. Chemical Vapor Deposition (CVD) and its plasma-enhanced variant (PECVD) offer conformal coatings and excellent control over film chemistry, which is particularly valuable for functional polymer and ceramic films. Other methods, such as sol–gel processing, ion beam deposition, and electrophoretic deposition, provide additional flexibility in terms of coating composition, adhesion, and processing temperature, allowing for the fabrication of films with tailored mechanical, chemical, and biological properties. Despite these advances, the field faces ongoing challenges in optimizing film properties for specific clinical applications, ensuring reproducibility, and scaling up production for widespread use. The necessity of this review lies in its comprehensive comparison of laser-based techniques with alternative deposition methods, providing critical insights into their respective strengths, limitations, and suitability for different biomedical scenarios. By synthesizing recent developments and highlighting current gaps, this review aims to guide researchers and clinicians in selecting the most appropriate thin-film deposition strategies to meet the evolving demands of next-generation biomedical devices. Full article
(This article belongs to the Special Issue Laser Techniques for Surface and Interface Engineering: Protocols and Applications in Materials Science)
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22 pages, 3852 KB  
Article
Reusable NiCo/Cu Catalysts for Sustainable Hydrogen Generation
by Gitana Valeckytė, Zita Sukackienė, Virginija Kepenienė, Raminta Šakickaitė, Jūratė Vaičiūnienė, Loreta Tamašauskaitė-Tamašiūnaitė, Jolanta Stupakova and Eugenijus Norkus
Materials 2026, 19(5), 852; https://doi.org/10.3390/ma19050852 - 25 Feb 2026
Cited by 1 | Viewed by 924
Abstract
The generation of high-purity hydrogen via chemical reaction from hydrogen-rich materials is one of the ways in the alternative energy industry. In this approach, the utilization of catalytic materials that possess the capacity to initiate the decomposition of the starting material and the [...] Read more.
The generation of high-purity hydrogen via chemical reaction from hydrogen-rich materials is one of the ways in the alternative energy industry. In this approach, the utilization of catalytic materials that possess the capacity to initiate the decomposition of the starting material and the subsequent release of hydrogen is of paramount importance. In this study, nickel/cobalt-plated copper catalysts (NiCo/Cu) are presented, comprising from 4 to 90 wt.% of cobalt as catalytic materials for hydrogen generation via sodium borohydride (NaBH4) hydrolysis reaction. The NiCo/Cu catalysts were synthesized via electroless deposition from glycine-based baths, utilizing Ni2+ and Co2+ ions as metal sources and morpholine borane (MB) as the reducing compound. The catalytic performance in alkaline NaBH4 hydrolysis was found to correlate with the cobalt loading in the coating. The maximum rate of hydrogen production, which was determined to be 14.22 L min−1 gcat−1, was achieved at 343 K for a catalyst composed of 90 wt.% Co. The reaction proceeded with the activation energy of 52.5 kJ mol−1, while the catalyst exhibited high durability, preserving nearly 88% of its initial activity after five successive reaction cycles. The combination of nickel and cobalt, along with their synergistic effect and high efficiency in the borohydride hydrolysis reaction, makes them promising catalysts. Full article
(This article belongs to the Section Catalytic Materials)
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16 pages, 3880 KB  
Article
Foam Rubber-Based Three-Layer Flexible Composite for High-Efficiency Infrared Stealth and Joule Heating
by Haishuo Li, Xiaojie Chen, Yushu Wang, Yaozong Li, Junjie Jiang and Wentao Zhai
Materials 2026, 19(4), 710; https://doi.org/10.3390/ma19040710 - 12 Feb 2026
Viewed by 554
Abstract
With the rapid development of infrared detection methods and military surveillance technologies, flexible and wearable infrared stealth materials (ISM) have attracted increasing attention. Inspired by the layered structure of penguins’ fat–feather–oil, this study prepared a three-layer MXene/waterborne polyurethane (WPU)-foam rubber-phase change microcapsule (PCM)/WPU [...] Read more.
With the rapid development of infrared detection methods and military surveillance technologies, flexible and wearable infrared stealth materials (ISM) have attracted increasing attention. Inspired by the layered structure of penguins’ fat–feather–oil, this study prepared a three-layer MXene/waterborne polyurethane (WPU)-foam rubber-phase change microcapsule (PCM)/WPU composite material (M-F-P) via the solution blending and doctor-blading method. The outermost layer of the M-F-P composite is an MXene/WPU conductive film, which features a low infrared emissivity and Joule heating performance to adapt to suddenly cold environments. The porous foam rubber in the middle layer provides excellent thermal insulation performance, which effectively inhibits heat conduction and enhances infrared stealth efficiency. Meanwhile, as a four-directional elastic material, it exhibits deformation recovery capability in both the warp and weft directions as well as the 45° direction. The bottom layer of the PCM/WPU film has a phase change enthalpy of 154.3 J/g and possesses efficient thermal management capability. It achieves dynamic thermal regulation through the cycle of heat absorption at high temperatures and heat release at low temperatures. Full article
(This article belongs to the Special Issue Advanced Composite Materials: Forming, Processing, Assembly and Maintenance)
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41 pages, 10153 KB  
Review
A Comprehensive Review on Sustainable Triboelectric Energy Harvesting Using Biowaste-Derived Materials
by Wajid Ali, Tabinda Shabir, Shahzad Iqbal, Syed Adil Sardar, Farhan Akhtar and Woo Young Kim
Materials 2026, 19(3), 592; https://doi.org/10.3390/ma19030592 - 3 Feb 2026
Cited by 2 | Viewed by 2011
Abstract
The growing demand for sustainable and distributed energy solutions has driven increasing interest in triboelectric nanogenerators (TENGs) as platforms for energy harvesting and self-powered sensing. Biowaste-based triboelectric nanogenerators (BW-TENGs) represent an attractive strategy by coupling renewable energy generation with waste valorization under the [...] Read more.
The growing demand for sustainable and distributed energy solutions has driven increasing interest in triboelectric nanogenerators (TENGs) as platforms for energy harvesting and self-powered sensing. Biowaste-based triboelectric nanogenerators (BW-TENGs) represent an attractive strategy by coupling renewable energy generation with waste valorization under the principles of the circular bioeconomy. This review provides a comprehensive overview of BW-TENGs, encompassing fundamental triboelectric mechanisms, material categories, processing and surface-engineering strategies, device architectures, and performance evaluation metrics. A broad spectrum of biowaste resources—including agricultural residues, food and marine waste, medical plastics, pharmaceutical waste, and plant biomass—is critically assessed in terms of physicochemical properties, triboelectric behavior, biodegradability, biocompatibility, and scalability. Recent advances demonstrate that BW-TENGs can achieve electrical outputs comparable to conventional synthetic polymer TENGs while offering additional advantages such as environmental sustainability, mechanical compliance, and multifunctionality. Key application areas, including environmental monitoring, smart agriculture, wearable and implantable bioelectronics, IoT networks, and waste management systems, are highlighted. The review also discusses major challenges limiting large-scale deployment, such as material heterogeneity, environmental stability, durability, and lack of standardization, and outlines emerging solutions involving material engineering, hybrid energy-harvesting architectures, artificial intelligence-assisted optimization, and life cycle assessment frameworks. Full article
(This article belongs to the Special Issue Materials, Design, and Performance of Nanogenerators)
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34 pages, 2781 KB  
Review
A Review on Sustainable Recycling of NdFeB Waste: Methodologies, Challenges, and the Integration of Machine Learning (ML)
by Rehan Ullah, Jason Daza, Asma Wederni, Lluisa Escoda, Joan Saurina and Joan-Josep Suñol
Materials 2026, 19(3), 594; https://doi.org/10.3390/ma19030594 - 3 Feb 2026
Cited by 2 | Viewed by 1513
Abstract
The increasing demand and production of neodymium-iron-boron-based permanent magnets (NdFeB-PMs) for the electronics, energy sector, and automobile industries led to disposal consequences. The NdFeB-PMs contain a substantial amount of rare earth elements (REEs). Although China is the largest exporter of REEs to the [...] Read more.
The increasing demand and production of neodymium-iron-boron-based permanent magnets (NdFeB-PMs) for the electronics, energy sector, and automobile industries led to disposal consequences. The NdFeB-PMs contain a substantial amount of rare earth elements (REEs). Although China is the largest exporter of REEs to the world, it has applied some restrictive policies in terms of supply chain and taxes. To address such issues, this review systematically examines current recycling techniques, including short-loop, hydrometallurgy, pyrometallurgy, and hybrid processes, and the integration of Machine Learning (ML) to the leaching process, with a particular focus on their impact on industrial capability, economic viability, and environmental concerns. However, a comparative study highlights ongoing challenges to large-scale implementation, including fragmented waste sources, gaps between efficient processes and environmental sustainability, and a lack of regulatory and infrastructure support. To address these challenges, technical innovation in automated disassembly systems and selective REE recovery via ML was discussed, along with legislative initiatives such as Extended Producer Responsibility (EPR) and waste monitoring procedures. Furthermore, ecologically and economically feasible solutions were optimized through ML-based recycling procedures to increase the leaching efficiency and the recovery of the REEs. This analysis emphasizes the importance of collective technological, environmental, and policy initiatives to achieve sustainable NdFeB recycling and long-term resource availability. These findings offer important perspectives into developing effective and environmentally friendly NdFeB waste recycling solutions via the integration of ML. Full article
(This article belongs to the Special Issue Advances in Magnetic Materials and Applications)
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21 pages, 4116 KB  
Article
Potential of Wood Processing Residues as Eco-Friendly Adsorbents for Wastewater Treatment
by Silviya Lavrova and Nikolay Yavorov
Materials 2026, 19(3), 578; https://doi.org/10.3390/ma19030578 - 2 Feb 2026
Cited by 2 | Viewed by 899
Abstract
In the context of global warming mitigation through energy conservation and pollution control, integrating green waste into treatment processes has become more popular. This study evaluated the potential of raw wood processing residues generated from furniture manufacturing as renewable sorbents for water treatment. [...] Read more.
In the context of global warming mitigation through energy conservation and pollution control, integrating green waste into treatment processes has become more popular. This study evaluated the potential of raw wood processing residues generated from furniture manufacturing as renewable sorbents for water treatment. Comparative studies assessed the Mn(II) removal efficiency of raw walnut (WW) and cherry (CW) wood shavings and the derived biochars (BChWW, BChCW) produced by hydropyrolysis. SEM, BET, FTIR, and TGA analyses characterized their surface and structural properties. CW demonstrated a higher adsorption capacity compared to WW. Physical activation enhanced the surface properties and Mn(II) adsorption affinity of the materials. Maximum adsorption capacities ranged from 2.1 to 2.2 mg/g for CW and WW, and 2.4 to 2.5 mg/g for BChCW and BChWW. The Freundlich model best fits to the data obtained using CW (R2 = 0.997) and BChCW (R2 = 0.984), while the RALF isotherm almost perfectly describes the mechanism of the Mn(II) adsorption onto WW (R2 = 0.999) and BChWW (R2 = 1.000). The pseudo second-order kinetic model shows strong agreement with experimental data, which suggests chemisorption on a heterogeneous surface. The results underscore the potential of wood industry byproducts as efficient and low-cost adsorbents for water treatment, supporting the circular economy and sustainable environmental management. Full article
(This article belongs to the Section Green Materials)
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25 pages, 4447 KB  
Article
Process–Microstructure–Property Characteristics of Aluminum Walls Fabricated by Hybrid Wire Arc Additive Manufacturing with Friction Stir Processing
by Ahmed Nabil Elalem and Xin Wu
Materials 2026, 19(3), 580; https://doi.org/10.3390/ma19030580 - 2 Feb 2026
Cited by 3 | Viewed by 1706
Abstract
Wire Arc Additive Manufacturing (WAAM) is a cost-effective method for fabricating large aluminum components; however, it tends to suffer from heat accumulation and coarse anisotropic microstructures, which can limit the part’s performance. In this study, a wall is fabricated using a hybrid unified [...] Read more.
Wire Arc Additive Manufacturing (WAAM) is a cost-effective method for fabricating large aluminum components; however, it tends to suffer from heat accumulation and coarse anisotropic microstructures, which can limit the part’s performance. In this study, a wall is fabricated using a hybrid unified additive deformation manufacturing process (UAMFSP) method, which integrates friction stir processing (FSP) into WAAM, and is compared with a Metal Inert Gas (MIG)-based WAAM wall. Infrared (IR) thermography revealed progressive heat buildup in MIG walls, with peak layer temperatures of about 870 to 1000 °C. In contrast, in the UAMFSP process, heat was redistributed through mechanical stirring, maintaining more uniform sub-solidus profiles below approximately 400 °C. Also, optical microscopy and quantitative image analysis showed that MIG walls developed coarse, dendritic grains with a mean grain area of about 314 µm2, whereas the UAMFSP produced refined, equiaxed grains with a mean grain area of about 10.9 µm2. Microhardness measurement (Vickers HV0.2, 200 gf) confirmed that the UAMFSP process can improve the hardness by 45.8% compared to the MIG process (75.8 ± 7.7 HV vs. 52.0 ± 1.3 HV; p = 0.0027). In summary, the outcomes of this study introduce the UAMFSP process as a method for addressing the thermal and microstructural limitations of WAAM. These findings provide a framework for further extending hybrid additive–deformation strategies to thicker builds, alternative alloys, and service-relevant mechanical evaluations. Full article
(This article belongs to the Section Manufacturing Processes and Systems)
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25 pages, 2463 KB  
Article
Green Deep Eutectic Solvents for Functionalizing Chitosan–Dialdehyde Materials with Varied Crosslinker Content
by Magdalena Gierszewska, Ewa Olewnik-Kruszkowska, Kornelia Kadac-Czapska, Małgorzata Grembecka and Eliza Knez
Materials 2026, 19(3), 529; https://doi.org/10.3390/ma19030529 - 29 Jan 2026
Viewed by 938
Abstract
A series of chitosan-based films was obtained by combining the covalent crosslinking of chitosan with dialdehyde starch (DAS) and plasticization using a choline chloride–malonic acid deep eutectic solvent (DES), thereby engineering their structural, mechanical, and surface properties for advanced packaging applications. DAS was [...] Read more.
A series of chitosan-based films was obtained by combining the covalent crosslinking of chitosan with dialdehyde starch (DAS) and plasticization using a choline chloride–malonic acid deep eutectic solvent (DES), thereby engineering their structural, mechanical, and surface properties for advanced packaging applications. DAS was synthesized via periodate oxidation of potato starch and characterized by FTIR and quantification of aldehyde groups through acid–base titration, enabling precise control of the –NH2 (chitosan) to –CHO (DAS) molar ratios (40:1, 20:1, 10:1) used for film formation. Chitosan films (neat, DAS-crosslinked, DES-plasticized, and DES-plasticized/DAS-crosslinked) were obtained by solution casting, with constant total chitosan and/or Ch+DES mass across formulations, and subsequently examined in terms of molecular structure, density, mechanical characteristics, micro- and nanoscale morphology, color, wettability, and surface free energy. The most significant changes relevant to potential applications were observed in mechanical properties and surface free energy. The incorporation of DAS and DES into chitosan resulted in a significant reduction in Young’s modulus from 1150 MPa to 130 MPa, accompanied by a significant increase in elongation at break—from 10% to almost 90%. Moreover, it should be noticed that the addition of DAS and DES led to a nearly twofold increase in surface free energy, from 32.5 to 59.9 mJ m−2. While previous studies have predominantly focused on single modifications of chitosan—either covalent crosslinking with dialdehyde starch (DAS) or plasticization with deep eutectic solvents (DES)—this work introduces a pioneering dual-modification strategy that simultaneously integrates both techniques, representing the first systematic investigation of their synergistic effects unattainable through individual approaches. Full article
(This article belongs to the Special Issue Sustainable Materials: Preparation, Characterization and Applications)
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19 pages, 1809 KB  
Article
Multistage Static and Dynamic Optimization Framework for Composite Laminates in Lightweight Urban Rail Vehicle Car Bodies
by Alessio Cascino, Francesco Distaso, Enrico Meli and Andrea Rindi
Materials 2026, 19(3), 531; https://doi.org/10.3390/ma19030531 - 29 Jan 2026
Cited by 4 | Viewed by 535
Abstract
This paper presents a robust multistage optimization framework for the integration of composite laminates into the car body shell of a low-floor light rail vehicle (LRV). While structural design in low-floor vehicles is typically complex, this methodology successfully balances both static and dynamic [...] Read more.
This paper presents a robust multistage optimization framework for the integration of composite laminates into the car body shell of a low-floor light rail vehicle (LRV). While structural design in low-floor vehicles is typically complex, this methodology successfully balances both static and dynamic requirements through a sequential optimization process. Developed in strict accordance with reference European standards, the methodology addresses the structural challenges inherent in low-floor architectures, where complex load paths and redistributed equipment masses require targeted reinforcement. The proposed approach sequentially addresses dynamic and static requirements through a structural optimization process. Two distinct 10-ply laminate configurations, one symmetric and one asymmetric, were investigated. The results demonstrate that the multistage optimization successfully converged to a highly mass-efficient solution, achieving a 66% reduction in laminate thickness compared to the baseline design. This significant result was accomplished while maintaining full regulatory compliance; the failure index increased by approximately 22.5% and 23.3% for the two composite laminate configurations, respectively, effectively maximizing material utilization. A key finding of this study is the preservation of structural dynamic integrity; the fundamental natural frequency was maintained at approximately 16 Hz, with a high correlation across the first ten vibration modes, confirming that the global dynamic behaviour remains unaffected. These observations provide critical insights into the synergy between hybridization and structural constraints, suggesting a systematic pathway for designers to achieve an optimal trade-off between manufacturing costs, weight reduction, and performance in advanced urban transit platforms. Full article
(This article belongs to the Special Issue Architected Lattice and Composite Materials: Multiscale Design, Manufacturing, and Applications)
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15 pages, 2626 KB  
Article
Synthesis and Study of Janus-Dione-Based Compounds for Ternary Organic Solar Cells
by Armands Ruduss, Anastasija Rizkova, Fatima Zohra Boudjenane, Elizabete Praulina, Kaspars Traskovskis and Raitis Grzibovskis
Materials 2026, 19(3), 533; https://doi.org/10.3390/ma19030533 - 29 Jan 2026
Viewed by 697
Abstract
The efficiency of organic solar cells is constantly improving thanks to more advanced materials. Electron donor polymers, such as PM6 and its derivatives, as well as non-fullerene acceptors (NFAs) Y6 and ITIC and their derivatives, have become the standard materials for organic solar [...] Read more.
The efficiency of organic solar cells is constantly improving thanks to more advanced materials. Electron donor polymers, such as PM6 and its derivatives, as well as non-fullerene acceptors (NFAs) Y6 and ITIC and their derivatives, have become the standard materials for organic solar cell studies. To broaden the absorption range of solar cells, so-called ternary organic solar cells have been developed, which add a third material to the active layer. In this work, two chromophores based on the derivatives of the Janus-dione (s-indacene-1,3,5,7(2H,6H)-tetraone) central acceptor fragment, namely TIIC-1 and TIIC-2, were synthesized. Materials were characterized using theoretical and experimental methods, including UV-Vis absorption measurements, cyclic voltammetry, photoemission yield spectroscopy, and photoconductivity. The materials were incorporated as ternary components in PM6:Y7 bulk heterojunction solar cells. The power conversion efficiency (PCE) of PM6:Y7:TIIC-1 ternary solar cells was improved compared to binary PM6:Y7 reference cells. The PCE increased from 11.9% in binary blends to 12.5% in ternary cells. This increase is attributed to the cascade-like energy level arrangement, which facilitates charge transfer in the photoactive layer. Full article
(This article belongs to the Section Energy Materials)
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15 pages, 1370 KB  
Article
Synthesis and Structural Characterization of Oligo(carbonate diol)s and Oligo(urethane-carbonate diol)s via a Transesterification–Polycondensation Route
by Mariusz Ł. Mamiński, Paweł G. Parzuchowski, Dominik Wołosz and Arkadiusz Zimny
Materials 2026, 19(2), 434; https://doi.org/10.3390/ma19020434 - 22 Jan 2026
Cited by 1 | Viewed by 1136
Abstract
Oligocarbonate diols (OCD) require tedious and time-consuming synthesis procedures. The most common ones use dimethyl carbonate or alkylene carbonate as starting materials. Considering the preparation of small batches of oligomerols with an atypical structure, this methodology is not convenient. Therefore, we developed a [...] Read more.
Oligocarbonate diols (OCD) require tedious and time-consuming synthesis procedures. The most common ones use dimethyl carbonate or alkylene carbonate as starting materials. Considering the preparation of small batches of oligomerols with an atypical structure, this methodology is not convenient. Therefore, we developed a simple way to obtain OCDs and oligo(urethane-carbonate) diols (OUCDs) containing aliphatic, cycloaliphatic, aromatic or oxyethylene units based on commercially available OCDs (ETERNACOLL, UBE). The process was conducted in two stages combining transesterification/transurethanization and polycondensation reactions. It resulted in novel OCDs and OUCDs with an irregular structure. Their composition was characterized using FT-IR, NMR, and MALDI-TOF techniques. The hydroxyl values were determined by potentiometric titration. The numerical average molar masses of the oligomerols ranged from approx. 1000 to 3200 g/mol, making them attractive materials for the preparation of a variety of polyurethane products. Thanks to the presence of carbonate moieties that are resistant to hydrolytic and oxidative degradation, poly(carbonate-urethane)s could find applications as coatings, thermoplastic elastomers, and biomaterials. The influence of the structural variations of the oligomerols on the properties of polyurethanes is now under investigation. Full article
(This article belongs to the Section Green Materials)
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