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Volume 17
Issue 12
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Polymers, Volume 17, Issue 12 (June-2 2025) – 133 articles

Cover Story (view full-size image): The need for new materials in tissue engineering has led research towards hydrogel-based systems. Tellurium-doped silanised bioactive glass, combined with chitosan-based hydrogels, offers a multi-function platform that combines antimicrobial and antioxidant activity with osteoconductive potential. This composite fights infections while supporting bone regeneration, making it a promising candidate for next-generation tissue engineering scaffolds. View this paper
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16 pages, 8906 KiB  
Article
Construction of Isotropy-Enhanced Honeycomb and Its Deformation Behaviors in Multi-Directions
by Junyuan Zheng and Guangdong Tian
Polymers 2025, 17(12), 1717; https://doi.org/10.3390/polym17121717 - 19 Jun 2025
Viewed by 475
Abstract
Honeycomb structures are widely constructed as cores in sandwich panels with lightweight characteristics and excellent out-of-plane properties. However, their in-plane performances are significantly inferior. This research proposed a novel isotropy-enhanced honeycomb (IEH) with interleaved layers, which is constructed by offsetting the initial seed [...] Read more.
Honeycomb structures are widely constructed as cores in sandwich panels with lightweight characteristics and excellent out-of-plane properties. However, their in-plane performances are significantly inferior. This research proposed a novel isotropy-enhanced honeycomb (IEH) with interleaved layers, which is constructed by offsetting the initial seed distributions across layers and then generating hexagonal cells via Voronoi tessellation. Numerical models with three layer-to-layer interval gradients were developed for simulations, and corresponding samples were additively manufactured for experimental validations. The in-plane and out-of-plane performances of IEH and the regular hexagonal honeycombs (RHHs) were comprehensively compared and investigated from quasi-static compression, energy absorption, mechanical properties, and dynamic loading. The results demonstrated that the IEH extremely enhances the in-plane properties by around 500% compared to the RHH, including stiffness, strength, plateau stress, and specific energy absorption (SEA). Although the improvements come at the expense of a partial reduction in out-of-plane stiffness, strength, and SEA, the in-plane performances of IEH reach approximately 70% of their out-of-plane performances, greatly improving the structural isotropy. Introducing layer-to-layer interval gradient leads to a slight reduction in out-of-plane mechanical properties while improving the early-stage deceleration under impact. These findings promote the considerable potential of sandwich panels utilizing IEH cores for applications requiring enhanced resistance to multi-directional impacts. Full article
(This article belongs to the Special Issue Structure, Properties and Analyses of Polymer Composites)
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11 pages, 2262 KiB  
Article
Sensitive and Stable NCF/GO/Au@Ag SERS Substrate for Trace Detection of Polycyclic Aromatic Hydrocarbons
by Lili Kong, Xinna Yu, Qifang Sun, Meizhen Huang, Tianyuan Liu and Jie Chen
Polymers 2025, 17(12), 1716; https://doi.org/10.3390/polym17121716 - 19 Jun 2025
Viewed by 370
Abstract
Polycyclic aromatic hydrocarbons (PAHs) have attracted significant attention due to their severe threats to both ecological systems and human health. In this paper, a high-performance surface-enhanced Raman spectroscopy (SERS) substrate based on NCF/GO/Au@Ag nanocomposites was developed, which enabled sensitive and stable detection of [...] Read more.
Polycyclic aromatic hydrocarbons (PAHs) have attracted significant attention due to their severe threats to both ecological systems and human health. In this paper, a high-performance surface-enhanced Raman spectroscopy (SERS) substrate based on NCF/GO/Au@Ag nanocomposites was developed, which enabled sensitive and stable detection of PAHs. The NCF/GO/Au@Ag substrate synergistic utilizes the localized surface plasmon resonance (LSPR) effect of Au@Ag core–shell nanorods and the additional interfacial charge transfer provided by graphene oxide (GO) to exhibit extremely high sensitivity. And the three-dimensional fibrous network of nanocellulose (NCF) improved nanoparticle dispersion uniformity. Combined finite element simulations and experimental studies verified that the dual plasmonic resonances (512 nm and 772 nm) of Au@Ag nanorods optimally match 785 nm excitation, yielding an enhancement factor of 5.21 × 105. GO integration enhanced Raman signals by 1.68-fold through interfacial charge transfer, while the introduction of NCF reduced the signal relative standard deviation (RSD) from 36.88% to 4.29%. The NCF/GO/Au@Ag substrate achieved a detection limit of 10 μg/L for PAHs, demonstrating exceptional sensitivity and reproducibility. Full article
(This article belongs to the Section Polymer Analysis and Characterization)
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13 pages, 4530 KiB  
Article
Preparation of Polystyrene Nanoparticles with Environmental Relevance Using a Gradual Degradation Method
by Hisayuki Nakatani, Mika Asano, Masaki Sakamoto, Suguru Motokucho, Anh Thi Ngoc Dao, Hee-Jin Kim, Mitsuharu Yagi and Yusaku Kyozuka
Polymers 2025, 17(12), 1715; https://doi.org/10.3390/polym17121715 - 19 Jun 2025
Viewed by 567
Abstract
This study investigates the environmental degradation of polystyrene (PS) microparticles and flakes using a gradual degradation method. The concentration of SO4•− decreased exponentially, simulating the environmental conditions. The nanofragment size of PS particles evolved dynamically, fluctuating from below 250 nm [...] Read more.
This study investigates the environmental degradation of polystyrene (PS) microparticles and flakes using a gradual degradation method. The concentration of SO4•− decreased exponentially, simulating the environmental conditions. The nanofragment size of PS particles evolved dynamically, fluctuating from below 250 nm at 3 days to 300–500 nm at 6 days, then forming two peaks below 200 nm at 9 days, before shifting to a single peak below 100 nm at 12 days. At 15 days, the distribution expanded to two peaks between 500 nm and 200 nm. The polydispersity index (PDI) varied unpredictably, and fragments below 100 nm fluctuated between 10 and 50 nm independent of time. SEM analysis revealed an initial peeling process, with the outermost layer peeling off. The core size of the PS particles decreased rapidly from 11,000 nm to 2500 nm within 6 days and stabilized at 1000 nm after 9 days. The PS flakes showed minimal shape change until 24 days, but surface roughness increased by 30 days, leading to fragmentation. By 42 days, the flakes partially broke into ca. 100 μm pieces. The initial morphology significantly influenced the breakdown pattern, suggesting multiple breakdown mechanisms other than peeling. Full article
(This article belongs to the Special Issue Degradation and Recycling of Polymer Materials)
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11 pages, 2573 KiB  
Article
Volvariella volvacea Processive Endoglucanase EG1 Treatment Improved the Physical Strength of Bleached Pulps and Reduced Vessel Picking in Eucalyptus Pulp
by Jiamin Yan, Yuemei Zhang and Shufang Wu
Polymers 2025, 17(12), 1714; https://doi.org/10.3390/polym17121714 - 19 Jun 2025
Viewed by 349
Abstract
Volvariella volvacea endoglucanase EG1 was used to treat bleached softwood kraft pulp (BSKP) and hardwood pulp (BHKP) to improve the refinability and physical strength, as well as to reduce vessel picking in Eucalyptus pulp. The results indicated that BSKP was treated with an [...] Read more.
Volvariella volvacea endoglucanase EG1 was used to treat bleached softwood kraft pulp (BSKP) and hardwood pulp (BHKP) to improve the refinability and physical strength, as well as to reduce vessel picking in Eucalyptus pulp. The results indicated that BSKP was treated with an enzyme dosage of 3 U/g for 2 h at 12,000 refining revolutions, which increased the tensile index from 71.4 N·m/g to 86.7 N·m/g. For BHKP, treatment with 10 U/g of EG1 for 2 h at 15,000 refining revolutions improved the tensile index from the control of 47.7 N·m/g to 56.9 N·m/g. Vessel-removed and vessel-enriched fractions of Eucalyptus pulp were obtained by screening and treated with EG1, respectively. It was found that EG1-assisted refining increased the physical strength and surface strength of both pulp fractions, and the latter improved even more, with increases of 22.4% and 160%, respectively. Full article
(This article belongs to the Special Issue Advances in Lignocellulose Research and Applications)
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22 pages, 6344 KiB  
Article
Tailoring the Properties of Magnetite/PLA Nanocomposites: A Composition-Dependent Study
by Mariana Martins de Melo Barbosa, Juliene Oliveira Campos de França, Quezia dos Santos Lima, Sílvia Cláudia Loureiro Dias, Carlos A. Vilca Huayhua, Fermín F. H. Aragón, José A. H. Coaquira and José Alves Dias
Polymers 2025, 17(12), 1713; https://doi.org/10.3390/polym17121713 - 19 Jun 2025
Viewed by 580
Abstract
This study focused on composites of magnetite magnetic nanoparticles (MNP) and poly(lactic acid) (PLA) prepared via sonochemical synthesis. The evaluation of MNP loadings (2, 5, 10, 15, and 20 wt.%) provided insights into the structural and reactivity properties of the materials. Methods used [...] Read more.
This study focused on composites of magnetite magnetic nanoparticles (MNP) and poly(lactic acid) (PLA) prepared via sonochemical synthesis. The evaluation of MNP loadings (2, 5, 10, 15, and 20 wt.%) provided insights into the structural and reactivity properties of the materials. Methods used included XRD, FT-IR and Raman spectroscopy, SEM and TEM microscopy, textural and thermal analysis (TG and DTA), and magnetic property measurements. The agreement between theoretical and experimental MNP loadings was good. XRD patterns showed predominantly MNP and semicrystalline phases, with a minor maghemite phase detected by FT-Raman and magnetic measurements. FT-IR analysis revealed interactions between MNP and PLA, confirmed by thermal analysis showing higher transition temperatures for the composites (145 °C) compared to pure PLA (139 °C). FT-Raman spectra also indicated that PLA helps prevent iron oxide oxidation, enhancing nanoparticle stability. SEM and TEM micrographs showed well-dispersed, spherical nanoparticles with minimal agglomeration, dependent on MNP loading. The nanocomposites exhibited low N2 adsorption, resulting in low surface area (~2.1 m2/g) and porosity (~0.03 cm3/g). Magnetic analysis indicated that in the 2MNP/PLA sample, MNP were in a superparamagnetic-like regime at 300 K, suggesting good dispersion of 2 wt.% MNP in the PLA matrix. Full article
(This article belongs to the Special Issue Recent Advances and Applications of Polymer Nanocomposites)
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20 pages, 4367 KiB  
Article
Design of Biomass Adsorbents Based on Bacterial Cellulose and E. crassipes for the Removal of Cr (VI)
by Uriel Fernando Carreño Sayago, Vladimir Ballesteros Ballesteros and Angelica María Lozano
Polymers 2025, 17(12), 1712; https://doi.org/10.3390/polym17121712 - 19 Jun 2025
Viewed by 413
Abstract
Cellulose has been identified as a medium for heavy metal removal due to its high adsorption capacity in relation to these contaminants. Furthermore, cellulose is abundant and can be obtained in a practical and easy way. A notable example is E. crassipes biomass, [...] Read more.
Cellulose has been identified as a medium for heavy metal removal due to its high adsorption capacity in relation to these contaminants. Furthermore, cellulose is abundant and can be obtained in a practical and easy way. A notable example is E. crassipes biomass, which is abundant in wetlands and has not yet been efficiently and sustainably removed. Another biomass that has been used in heavy metal removal projects is bacterial cellulose. Generating this biomass in a laboratory setting is imperative, given its 100% cellulose composition, which ensures optimal adsorption capacities during the development of heavy metal adsorbent systems. Therefore, the objective of this project was to design biomass adsorbents that combine the properties of bacterial and E. crassipes cellulose for Cr(VI) removal. The rationale for combining these two materials is based on the premise that it will produce optimal results, a hypothesis supported by the documented efficiency of bacterial cellulose and the formidable resilience of E. crassipes biomass to elution processes. The second-order model and the Langmuir isotherm fit proved to be the most suitable, indicating that there an occurred interaction between the adsorption sites of these biomasses and Cr (VI). This suggests the presence of a significant number of active sites on the surface of these materials. The EC(50)+BC(50) biomass, with an adsorption capacity of 42 g of Cr(VI) per dollar, is the most cost-effective due to the low cost of E. crassipes and the high capacity of bacterial cellulose. It is a mixture that guarantees high adsorption capacities and facilitates up to seven reuse cycles through elutions with ethylenediaminetetraacetic acid (EDTA). This finding emphasizes the potential of this material for implementation in environmental sustainability initiatives, particularly those focused on the removal of heavy metals, including Cr(VI). Full article
(This article belongs to the Special Issue Cellulose and Cellulose Micro/Nanomaterials: Recent Research and Applications)
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11 pages, 1353 KiB  
Article
Adhesion of 3D-Printed Versus Milled Resin Posts to Composite Resin Core Build-Up Material: Influence of Surface Treatments
by Khalid K. Alanazi, Ali Robaian Alqahtani, Abdullah Mohammed Alshehri, Abdullah Ali Alqahtani, Abdulellah Almudahi, Omar Abdulaziz Al-Mansour, Nawaf Abdullah Al-Harbi, Sultan Sahman Abdulrahman Alqahtani, Eman Mohamed Raffat Hussein and Tarek Ahmed Soliman
Polymers 2025, 17(12), 1711; https://doi.org/10.3390/polym17121711 - 19 Jun 2025
Viewed by 486
Abstract
Background: There are very few studies in literature concerning the bonding between 3D-printed resin posts and the core build-up material. This study aimed to evaluate and compare the adhesion of 3D-printed and milled resin posts to composite resin core build-up material following different [...] Read more.
Background: There are very few studies in literature concerning the bonding between 3D-printed resin posts and the core build-up material. This study aimed to evaluate and compare the adhesion of 3D-printed and milled resin posts to composite resin core build-up material following different surface treatments. Methods: Three types of resin posts were utilized in this study: ready-made glass-reinforced fiber post (3M ESPE, Germany), milled PEEK POST (Bredent, Germany), and 3D-printed resin post (CROWNTEC, Saremco Dental AG, Switzerland). Each type of post was categorized into three groups based on surface treatments: C: untreated surfaces; SB: Air abrasion with 50 μm aluminum oxide particles was applied to the posts’ surfaces.; HO: the posts’ surfaces were immersed in 30% H2O2 for 5 min. A dual-cured composite resin (Grandio DC; VOCO) was utilized for core build-up in each group to evaluate adhesion through the push-out bond strength test. The modes of failure were analyzed, and the surface morphology of the post was characterized using SEM. Data were analyzed using a two-way analysis of variance (ANOVA) along with Tukey’s test. Results: The two-way ANOVA indicated a significant effect for surface treatment (F = 583.54, p < 001), post type (F = 79.96, p < 0.001), and their interactions (F = 265.74, p < 0.001). Regarding 3D-printed resin post, 30% H2O2 for 5 min recorded the highest statistically significant bond strength value (13.11 ± 1.61) compared to other groups. Regarding the milled PEEK post, the air particle abrasion recorded the highest statistically significant value (23.88 ± 1.66) compared to other groups. Adhesive failure was the predominant failure type, with an occurrence rate of 70.35%. Mixed failure was noted in 24.07% of the cases, with a significant prevalence in the PEEK post within the air particle abrasion group (58.3%). Cohesive failure was noted in 5.54% of cases, with a significant prevalence in the air particle abrasion group, occurring at rates of 16.6% in the resin fiber post group and 33.3% in PEEK posts. Conclusions: Air particle abrasion significantly improved the push-out bond strength of milled PEEK posts, but it did not have a similar effect on the 3D-printed resin posts. The application of 30% H2O2 for 5 min to 3D-printed resin post enhanced the adhesion to core build-up material. The manufacturing method of posts, the surface treatments utilized, and their interactions affect the interfacial bond strength between posts and the composite resin core build-up material. Full article
(This article belongs to the Special Issue Functional Polymeric Materials for Dental and Oral and Maxillofacial Surgery Applications)
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24 pages, 49414 KiB  
Article
Geopolymer Concrete Physical and Mechanical Properties on a Combined Binder Reinforced with Dispersed Polypropylene Fiber
by Sergei A. Stel’makh, Alexey N. Beskopylny, Evgenii M. Shcherban, Diana Elshaeva, Andrei Chernilnik, Denis Kuimov, Alexandr Evtushenko and Samson Oganesyan
Polymers 2025, 17(12), 1710; https://doi.org/10.3390/polym17121710 - 19 Jun 2025
Cited by 1 | Viewed by 643
Abstract
Geopolymer concrete is a promising construction material that acts as an alternative to cement concrete. Unlike traditional cement concrete, geopolymers are environmentally friendly materials, the production of which does not involve significant carbon dioxide emissions. However, the structure formation and properties of geopolymers [...] Read more.
Geopolymer concrete is a promising construction material that acts as an alternative to cement concrete. Unlike traditional cement concrete, geopolymers are environmentally friendly materials, the production of which does not involve significant carbon dioxide emissions. However, the structure formation and properties of geopolymers significantly depend on raw materials and are insufficiently studied. The aim of the study is to select the optimal combination of ground granulated blast furnace slag (GGBS) and fly ash (FA) as a binder and the optimal content of polypropylene fiber to create a sustainable, environmentally friendly and effective geopolymer concrete. To study various compositions of geopolymer binders selected by combining GGBS and FA, experimental geopolymer concrete mixtures and samples from them were manufactured. The density and slump of fresh concrete and the density and compressive strength of hardened composites were studied as mechanical characteristics. The microstructure of the geopolymer matrix was analyzed using optical and scanning electron microscopes. The most rational combination of GGBS 80% and FA 20% was determined, which allows obtaining a composite with the highest compressive strength of up to 31.5 MPa. A dispersion reinforcement study revealed that 0.8% polypropylene fiber (PF) is optimal. This allowed us to increase the compressive strength by 7.3% and the flexural strength by 48.7%. The geopolymer fiber concrete obtained in this study is a sustainable and environmentally friendly alternative composite material and has sufficient performance properties for its use as an alternative to cement concrete. Full article
(This article belongs to the Special Issue Fiber Reinforced Polymers Applications as Reinforcement of Concrete Structures—Design Aspects, Tests and Analysis, 2nd Edition)
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31 pages, 4369 KiB  
Article
Medicago Sativa Stems—A Multi-Output Integrated Biorefinery Approach
by Adrian Cătălin Puițel, George Bârjoveanu, Cătălin Dumitrel Balan and Mircea Teodor Nechita
Polymers 2025, 17(12), 1709; https://doi.org/10.3390/polym17121709 - 19 Jun 2025
Viewed by 356
Abstract
This study presents an investigation on the potential of using one-year-old field-stored Medicago sativa (alfalfa) as a raw material for a multi-output biorefinery. The main objective was to fractionate the biomass into valuable components—crude protein, hemicellulose-derived polysaccharides, lignin, and cellulose—and to explore the [...] Read more.
This study presents an investigation on the potential of using one-year-old field-stored Medicago sativa (alfalfa) as a raw material for a multi-output biorefinery. The main objective was to fractionate the biomass into valuable components—crude protein, hemicellulose-derived polysaccharides, lignin, and cellulose—and to explore the latter’s suitability in papermaking. To this end, three pretreatment strategies (water, alkaline buffer, and NaOH solution) were applied, followed by soda pulping under varying severity conditions. Both solid and liquid fractions were collected and chemically characterized using FTIR, HPLC, and standardized chemical methods. Water-based pretreatment was most effective for protein extraction, achieving over 40% protein content in precipitated fractions. The harshest pulping conditions (20% NaOH, 160 °C, 60 min) yielded cellulose-rich pulp with high glucan content, while also facilitating lignin and hemicellulose recovery from black liquor. Furthermore, the pulps derived from alfalfa stems were tested for papermaking. When blended with old corrugated cardboard (OCC), the fibers enhanced tensile and burst strength by 35% and 70%, respectively, compared to OCC alone. These findings support the valorization of unexploited alfalfa deposits and suggest a feasible biorefinery approach for protein, fiber, and polymer recovery, aligned with circular economy principles. Full article
(This article belongs to the Special Issue Recent Progress on Lignocellulosic-Based Polymeric Materials)
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27 pages, 10394 KiB  
Article
Preparation of a Biomedical Scaffold from High-Molecular-Weight Poly-DL-Lactic Acid Synthesized via Ring-Opening Polymerization
by Geraldine Denise Bazan-Panana, Manuel J. Torres-Calla and María Verónica Carranza-Oropeza
Polymers 2025, 17(12), 1708; https://doi.org/10.3390/polym17121708 - 19 Jun 2025
Viewed by 444
Abstract
In this study, poly-DL-lactic acid (PDLLA) was synthesized via ring-opening polymerization (ROP) to develop a biomedical scaffold for tissue engineering. A rotary evaporator with a two-stage vacuum pump under an inert atmosphere and constant stirring was used. A factorial design with three factors [...] Read more.
In this study, poly-DL-lactic acid (PDLLA) was synthesized via ring-opening polymerization (ROP) to develop a biomedical scaffold for tissue engineering. A rotary evaporator with a two-stage vacuum pump under an inert atmosphere and constant stirring was used. A factorial design with three factors (oligomerization time, ROP time, and catalyst concentration) at two levels was applied. Polymers were characterized by FTIR, capillary viscometry, 1H-NMR, DSC, and TGA. The kinetic study revealed a first-order model, indicating that the polymerization rate depends linearly on monomer concentration. The activation energy (70.5 kJ/mol) suggests a moderate energy requirement, consistent with ring-opening polymerization, while the high pre-exponential factor (6.93 × 106 min−1) reflects a significant frequency of molecular collisions. The scaffold was fabricated via extrusion and 3D printing, and its morphology, porosity, mechanical properties, and contact angle were studied. The highest molecular weight PDLLA was obtained with 6 h of oligomerization, 4 h of ROP, and 1% catalyst concentration. The samples exhibited thermal stability below 40 °C, while the scaffold reached 71.6% porosity, an 85.97° contact angle, and a compressive strength of 4.24 MPa with an elastic modulus of 51.7 MPa. These findings demonstrate the scaffold’s potential for biomedical applications. Full article
(This article belongs to the Special Issue Advances in Functional Polymer Materials for Biomedical Applications)
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30 pages, 4768 KiB  
Article
Polysaccharide Composites with Rosa canina for Sustained Anti-Inflammatory Skin Therapy
by Narcis Anghel, Irina Apostol, Ioana Plaesu, Alice Mija, Natalia Simionescu, Adina Coroaba and Iuliana Spiridon
Polymers 2025, 17(12), 1707; https://doi.org/10.3390/polym17121707 - 19 Jun 2025
Viewed by 473
Abstract
This study presents novel skin-compatible biomaterials based on guar gum and dextran sulfate matrices, incorporating softwood lignin, lignin esterified with aspartic acid, and Rosa canina extract. The materials were prepared via casting and evaluated for physicochemical, mechanical, and biological properties. Spectroscopic analyses confirmed [...] Read more.
This study presents novel skin-compatible biomaterials based on guar gum and dextran sulfate matrices, incorporating softwood lignin, lignin esterified with aspartic acid, and Rosa canina extract. The materials were prepared via casting and evaluated for physicochemical, mechanical, and biological properties. Spectroscopic analyses confirmed successful lignin esterification, with new carbonyl and amide peaks and a nitrogen signal (3.83%) detected. Rosa canina extract enhanced the Young’s modulus from 1.42 MPa to 3.18 MPa and reduced elongation at break from 34.88 mm to 25.19 mm. The combination of esterified lignin and Rosa canina showed the greatest mechanical reinforcement (3.74 MPa modulus, 23.78 mm elongation). Swelling capacity decreased from 0.40 to 0.23 g water/g material and followed pseudo-second-order kinetics (R2 = 0.991–0.998). The release of Rosa canina bioactives followed the Makoid–Banakar model, indicating a transition from rapid to sustained release. All formulations exhibited anti-inflammatory activity with over 45% protein denaturation inhibition, peaking at 61.58% for the Rosa canina-only sample. In vitro biocompatibility assays demonstrated over 80% cell viability, confirming the potential of these biomaterials for dermal applications. Full article
(This article belongs to the Special Issue Advances in Polymer-Based Drug Delivery Systems for Cutaneous Applications)
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17 pages, 2920 KiB  
Article
Core-Dependent Desorption Behavior of Polyelectrolyte Microcapsules in NaCl and Na2SO4 Solutions
by Alexey V. Dubrovskii, Aleksandr L. Kim and Sergey A. Tikhonenko
Polymers 2025, 17(12), 1706; https://doi.org/10.3390/polym17121706 - 19 Jun 2025
Viewed by 389
Abstract
Polyelectrolyte microcapsules (PMCs) have a wide range of applications in fields such as medicine, pharmacology, diagnostics, etc., and can be used as targeted drug delivery vehicles, diagnostic systems and smart materials. However, the existing research indicates that the type of core can influence [...] Read more.
Polyelectrolyte microcapsules (PMCs) have a wide range of applications in fields such as medicine, pharmacology, diagnostics, etc., and can be used as targeted drug delivery vehicles, diagnostic systems and smart materials. However, the existing research indicates that the type of core can influence the properties of the PMC shell. Consequently, we hypothesized that the type of core used for the formation of the PMC may also affect the desorption of the shell’s polyelectrolytes. In this study, the desorption of polyelectrolytes of PMCs, formed on polystyrene cores (PMCPs) and MnCO3 (PMCMn) and CaCO3 cores (PMCCa), incubated in either NaCl or Na2SO4 solution, was investigated. It was demonstrated that the low ionic strength of the solution (up to 200 mM NaCl) has a negligible effect on the desorption of PMCCa. However, in the case of PMCPs and PMCMn, an increase in desorption was observed at 100 and 200 mM NaCl. Increasing the ionic strength to 1000 mM and 2000 mM resulted in a gradual increase in the desorption of the polyelectrolytes PMCCa and PMCMn, while for PMCPs, the maximum desorption was already observed at 1000 mM. Additionally, an increase in desorption was detected upon incubation in various concentrations of sodium sulfate (5–50 mM), although the desorption did not differ significantly across all types of PMCs. Nevertheless, for PMCMn, the maximum desorption was observed at a sodium sulfate concentration of 50 mM, whereas for other types of capsules, the maximum desorption occurred at a concentration of 100 mM. These results support the hypothesis that the type of core used in the formation of PMCs influences the desorption of the shell polyelectrolyte. Full article
(This article belongs to the Section Polymer Applications)
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15 pages, 3993 KiB  
Article
Study on the Electrospinning Fabrication of PCL/CNTs Fiber Membranes and Their Oil–Water Separation Performance
by Desheng Feng, Yanru Li, Yanjun Zheng, Jinlong Chen, Xiaoli Zhang, Kun Li, Junfang Shen and Xiaoqin Guo
Polymers 2025, 17(12), 1705; https://doi.org/10.3390/polym17121705 - 19 Jun 2025
Viewed by 393
Abstract
This study focused on the preparation of poly(ε-caprolactone)/carbon nanotubes (PCL/CNTs) composite membranes via electrospinning technology and investigated their performance in oil–water separation. The effects of varying CNTs contents and spinning parameters on the structure and properties of the membrane materials were systematically studied. [...] Read more.
This study focused on the preparation of poly(ε-caprolactone)/carbon nanotubes (PCL/CNTs) composite membranes via electrospinning technology and investigated their performance in oil–water separation. The effects of varying CNTs contents and spinning parameters on the structure and properties of the membrane materials were systematically studied. A highly uniform diameter distribution of the PCL fiber was achieved by using the dichloromethane/dimethylformamide (DCM/DMF) composite solvent with volume ratio of 7:3, as well as a PCL concentration of ca. 17 wt.%. The optimal electrospinning parameters were identified as an applied voltage of 18 kV and a syringe pump flow rate of 1 mL·h−1, which collectively ensured uniform fiber morphology under the specified processing conditions. The critical threshold concentration of CNTs in the composite system was determined to be 1 wt.%, above which the composite fibers exhibit a significant increase in diameter heterogeneity. Both pristine PCL fibrous membranes and PCL/CNTs composite membranes demonstrated excellent and stable oil–water separation performance, with separation efficiencies consistently around 90%. Notably, no significant attenuation in separation efficiency was observed after ten consecutive separation cycles. Furthermore, when incorporating 0.5 wt.% CNTs, the PCL/CNT composite membranes exhibited a 20% increase in separation flux for heavy oils compared to pristine PCL membranes. Additionally, CNTs, as a prototypical class of nanofillers for polymer matrix reinforcement, can potentially enhance the mechanical properties of composite films, thus effectively prolonging their service life. Full article
(This article belongs to the Special Issue Development in Carbon-Fiber-Reinforced Polymer Composites)
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19 pages, 3219 KiB  
Article
Development and Mechanical Analysis of Geopolymers Formed with Mining Residue and Fly Ash from Municipal Solid Waste Incineration Obtained After the Neutralisation Stage
by Antonia Terrones-Saeta, Juan María Terrones-Saeta, Jorge Suárez-Macías, Francisco Javier Iglesias-Godino and Francisco Antonio Corpas-Iglesias
Polymers 2025, 17(12), 1704; https://doi.org/10.3390/polym17121704 - 19 Jun 2025
Viewed by 253
Abstract
Renewable energy sources are presented as a key solution to today’s energy needs, but they also generate waste that can have a negative impact on the environment. In particular, fly ash from the incineration of municipal solid waste (MSW), classified as hazardous by [...] Read more.
Renewable energy sources are presented as a key solution to today’s energy needs, but they also generate waste that can have a negative impact on the environment. In particular, fly ash from the incineration of municipal solid waste (MSW), classified as hazardous by European regulations, is often deposited in landfills due to its lack of usefulness. This research proposes its valorisation in geopolymers, combining it with mining to create a sustainable material with a high industrial waste content. Firstly, all the wastes involved were characterised, which allowed for the development of a high-quality geopolymer from mining residue activated with 5% NaOH. This material was enriched with up to 50% fly ash (in increasing percentages) with the aim of making it inert, retaining it in the geopolymer matrix, and observing its effect on the final material. The physical and mechanical properties of the geopolymers obtained were evaluated, demonstrating that they do not produce contaminating leachates. The results indicate the feasibility of developing a geopolymer with up to 20% fly ash, obtaining a building material comparable to traditional ceramics, suitable for commercialisation, with a lower environmental impact and in line with the principles of the circular economy. Full article
(This article belongs to the Special Issue Technological Innovations for Polymer Circularity: Upcycling, Biodegradation, and Processing)
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26 pages, 14457 KiB  
Article
Molecular Simulation of the Isotropic-to-Nematic Transition of Rod-like Polymers in Bulk and Under Confinement
by Biao Yan, Daniel Martínez-Fernández, Katerina Foteinopoulou and Nikos Ch. Karayiannis
Polymers 2025, 17(12), 1703; https://doi.org/10.3390/polym17121703 - 19 Jun 2025
Viewed by 548
Abstract
We conduct extensive Monte Carlo simulations to investigate the factors that control the isotropic-to-nematic transition of hard colloidal polymers in bulk and under various conditions of confinement. Utilizing a highly idealized model, polymers are represented as linear chains of tangent hard spheres of [...] Read more.
We conduct extensive Monte Carlo simulations to investigate the factors that control the isotropic-to-nematic transition of hard colloidal polymers in bulk and under various conditions of confinement. Utilizing a highly idealized model, polymers are represented as linear chains of tangent hard spheres of uniform length, whose stiffness is controlled by a bending potential leading to rod-like configurations. Confinement is realized through the presence of flat, parallel, and impenetrable walls in one, two, or three dimensions while periodic boundary conditions are applied on the unconstrained dimensions. All simulations are performed through the Simu-D software, composed of conventional and advanced, chain-connectivity-altering Monte Carlo algorithms. We explore in detail how distinct factors, including chain length, stiffness, confinement, and packing density affect the isotropic-to-nematic transition exhibited by the polymer chains and identify with high precision the concentration range where this phase change takes place as a function of the applied conditions. Full article
(This article belongs to the Special Issue Semiflexible Polymers, 3rd Edition)
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13 pages, 3262 KiB  
Article
Bio-Inspired PG/PEI Co-Deposition for Interfacial Modification of HMX/F2602
by Ningxin Ma, Wenzheng Xu, Xiaolong Chang and Shuying Lan
Polymers 2025, 17(12), 1702; https://doi.org/10.3390/polym17121702 - 19 Jun 2025
Viewed by 411
Abstract
The issue of interfacial inhomogeneity in energetic materials remains a significant challenge. In this study, fluoroelastomer F2602 was applied to HMX crystals using a water suspension granulation technique, followed by a bio-inspired coating formed via the crosslinking polymerization of polyethyleneimine (PEI) and pyrogallol [...] Read more.
The issue of interfacial inhomogeneity in energetic materials remains a significant challenge. In this study, fluoroelastomer F2602 was applied to HMX crystals using a water suspension granulation technique, followed by a bio-inspired coating formed via the crosslinking polymerization of polyethyleneimine (PEI) and pyrogallol (PG) on the HMX/F2602 composite. This process resulted in the formation of an HMX/F2602/PEI-PG microcapsule structure. Various characterization techniques confirmed that the chemical structure and polycrystalline morphology of the crystals were preserved throughout the coating process, maintaining the characteristic β-HMX morphology. The introduction of the PG–PEI shell significantly improved the coating coverage and minimized the exposure of crystal surfaces. Furthermore, compared to HMX/F2602, the HMX/F2602/PEI-PG composite exhibited notably enhanced thermal stability and reduced mechanical sensitivity. These improvements are attributed to the advantageous effects of the microcapsule structure formed by the bio-inspired coating on the material’s properties. Full article
(This article belongs to the Section Polymer Chemistry)
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14 pages, 6399 KiB  
Article
Core–Shell CoS2/FeS2 Heterojunction Encapsulated in N-Doped Carbon Nanocubes Derived from Coordination Polymers for Electrocatalytic Alkaline Water/Seawater Splitting
by Xiaoyin Zhang, Yan Liu, Zihan Zeng, Yan Zou, Wanzhen Wang, Jing Zhang, Jing Wang, Xiangfeng Kong and Xiangmin Meng
Polymers 2025, 17(12), 1701; https://doi.org/10.3390/polym17121701 - 19 Jun 2025
Viewed by 460
Abstract
Utilizing renewable energy for green hydrogen production via electrolyzed seawater is a promising technology for the future. However, undesired chlorine evolution and the corrosive nature of seawater are crucial challenges for direct seawater splitting technology. In this work, heterojunctions of CoS2/FeS [...] Read more.
Utilizing renewable energy for green hydrogen production via electrolyzed seawater is a promising technology for the future. However, undesired chlorine evolution and the corrosive nature of seawater are crucial challenges for direct seawater splitting technology. In this work, heterojunctions of CoS2/FeS2 encapsulated in N-doped carbon nanocubes (denoted as CoS2/FeS2@NC) were designed by proposing the synchronous pyrolysis and vulcanization of polydopamine-coated coordination polymers. Such a synthetic strategy was demonstrated to be effective in increasing the favorable exposure of active sites, moderately regulating electronic structure, and remarkably facilitating charge transfer due to the controllable generation of unique core–shell structures with suitable carbon shells, leading to the excellent bifunctional electrocatalytic performance and enhanced stability of electrocatalysts. As a result, CoS2/FeS2@NC can be revealed as a superior water splitting catalyst, possessing a small voltage of 1.75 V and requiring 100.0 mA cm−2 in 1 M KOH alkaline solution and 1.80 V for alkaline seawater media, with satisfactory long-term stability. This work presents fresh strategies for designing core–shell heterostructures and developing green technology for hydrogen production. Full article
(This article belongs to the Special Issue Design, Synthesis and Application of Coordination-Driven Metal-Organic Supramolecular Polymers)
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17 pages, 6263 KiB  
Article
The Characterization of Polymers That Mimic the Aortic Wall’s Mechanical Properties and Their Suitability for Use in the 3D Printing of Aortic Phantoms
by Moritz Wegner, Benan Sahin Karagoez, David Wippel, Florian K. Enzmann, Anja Niehoff, Oroa Salem and Bernhard Dorweiler
Polymers 2025, 17(12), 1700; https://doi.org/10.3390/polym17121700 - 19 Jun 2025
Viewed by 577
Abstract
(1) While three-dimensional (3D) printing technology is increasingly being used for the fabrication of high-fidelity, patient-specific aortic models, data on the mechanical properties of polymers are sparse. Therefore, the aim of this study was to identify suitable polymers for this purpose. (2) Methods: [...] Read more.
(1) While three-dimensional (3D) printing technology is increasingly being used for the fabrication of high-fidelity, patient-specific aortic models, data on the mechanical properties of polymers are sparse. Therefore, the aim of this study was to identify suitable polymers for this purpose. (2) Methods: Eight flexible polymers, with Shore A hardnesses (ShA) of 27–85, were tested to determine their suitability for PolyJet printing technology. They were tested against porcine aortic and bovine pericardial tissue for suture retention strength, uniaxial stress testing according to ISO 37, and burst pressure in a standardized test setting. (3) Results: The polymers with a ShA of 30–50 showed statistically non-inferior suture retention strength, tensile strength, and burst pressure resistance when compared to pericardial and aortic tissue, respectively. (4) Conclusions: This was the first report to analyze the mechanical properties of eight different flexible PolyJet polymers. We found that the polymers with a Shore A hardness of 30–50 most closely mimicked the mechanical properties of aortic tissue. Therefore, they can be recommended for the additive manufacturing (3D printing) of aortic phantoms for simulation and training purposes. Full article
(This article belongs to the Section Innovation of Polymer Science and Technology)
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28 pages, 6197 KiB  
Systematic Review
Risk Assessment of Microplastics in Humans: Distribution, Exposure, and Toxicological Effects
by Yifei Li, Wei Ling, Jian Yang and Yi Xing
Polymers 2025, 17(12), 1699; https://doi.org/10.3390/polym17121699 - 18 Jun 2025
Viewed by 1314
Abstract
Microplastics are widely present in the environment, and their potential risks to human health have attracted increasing attention. Research on microplastics has exhibited exponential growth since 2014, with a fast-growing focus on human health risks. Keyword co-occurrence networks indicate a research shift from [...] Read more.
Microplastics are widely present in the environment, and their potential risks to human health have attracted increasing attention. Research on microplastics has exhibited exponential growth since 2014, with a fast-growing focus on human health risks. Keyword co-occurrence networks indicate a research shift from environmental pollution toward human exposure and health effects. Additionally, Trend Factor analysis reveals emerging research topics such as reproductive toxicity, neurotoxicity, and impacts on gut microbiota. This meta-analysis included 125 studies comprising 2977 data samples. The results demonstrated that cytotoxicity in experimental systems was primarily concentrated in Grade I (non-toxic, 62.8%) and Grade II (mildly toxic, 27.6%). Notably, inhibitory effects on cells were significantly enhanced when microplastic concentrations exceeded 40 μg/mL or particle sizes were smaller than 0.02 μm. The Gradient Boosting Decision Tree (GBDT) model was applied to predict cell viability, achieving an R2 value of 0.737 for the test set and a classification accuracy of 81.5%. Furthermore, reproductive- and circulatory-system cells exhibited the highest sensitivity to microplastics, whereas connective-tissue cells had the lowest survival rates. The study also identified an overuse of polystyrene (PS) polymers and spherical particles in experimental designs, deviating from realistic exposure scenarios. Full article
(This article belongs to the Section Polymer Applications)
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15 pages, 5032 KiB  
Article
Comparative Analysis of Dimensional Accuracy in PLA-Based 3D Printing: Effects of Key Printing Parameters and Related Variables
by Yifan Li, Amin Molazem, Hong-I Kuo, Vincent Ahmadi and V. Prasad Shastri
Polymers 2025, 17(12), 1698; https://doi.org/10.3390/polym17121698 - 18 Jun 2025
Viewed by 478
Abstract
This study examines the impact of key printing parameters on the dimensional accuracy of 3D printing, specifically Fused Deposition Modeling (FDM) using PLA, utilizing two widely adopted printers: the LulzBot TAZ Pro and the Prusa MK4. A simplified parallel-line model was used to [...] Read more.
This study examines the impact of key printing parameters on the dimensional accuracy of 3D printing, specifically Fused Deposition Modeling (FDM) using PLA, utilizing two widely adopted printers: the LulzBot TAZ Pro and the Prusa MK4. A simplified parallel-line model was used to systematically evaluate the effects of print speed, nozzle temperature, bed temperature, and layer height on accuracy along the X, Y, and Z axes. The results showed that the Prusa MK4 generally provided better dimensional accuracy at lower print speeds (20–40 mm/s), higher nozzle temperatures (230 °C), and smaller layer heights (0.05 mm). In contrast, the LulzBot TAZ Pro performed better at higher print speeds (40–60 mm/s) and with thicker layers (0.2 mm). Scanning electron microscopy analysis further revealed distinct surface morphologies depending on the printer and parameter settings. These findings offer practical guidance for selecting suitable print settings across various application areas. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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23 pages, 4651 KiB  
Article
High-Expansion Natural Composite Films for Controlled Delivery of Hydroxycitric Acid in Obesity Therapy
by Kantiya Fungfoung, Ousanee Issarachot, Rachanida Praparatana and Ruedeekorn Wiwattanapatapee
Polymers 2025, 17(12), 1697; https://doi.org/10.3390/polym17121697 - 18 Jun 2025
Viewed by 633
Abstract
Expandable films represent a promising gastroretentive drug delivery system, offering prolonged gastric retention and sustained drug release features particularly advantageous for obesity treatment. This study developed high-expansion films using konjac and various low glycemic index starches, including purple potato, brown rice, resistant, and [...] Read more.
Expandable films represent a promising gastroretentive drug delivery system, offering prolonged gastric retention and sustained drug release features particularly advantageous for obesity treatment. This study developed high-expansion films using konjac and various low glycemic index starches, including purple potato, brown rice, resistant, and red jasmine rice starches, in combination with chitosan and hydroxypropyl methylcellulose (HPMC) E15. Garcinia extract was incorporated into the films using the solvent casting technique. Among 27 formulations, all demonstrated rapid unfolding (within 15 min) and significant expansion (2-4 folds). Hydroxycitric acid (HCA), the active component, was encapsulated at efficiencies exceeding 80% w/w. The konjac-based films exhibited favorable mechanical properties, expansion capacity, and drug content uniformity. Notably, the CK3-H1 formulation (2% w/v chitosan, 3% w/v konjac, 1% w/v HPMC E15) provided sustained HCA release over 8 h via diffusion. Cytotoxicity tests showed no toxic effects on RAW 264.7 macrophages at concentrations up to 400 μg/mL. Furthermore, CK3-H1 achieved notable nitric oxide inhibition (35.80 ± 1.21%) and the highest reduction in lipid accumulation (31.09 ± 3.15%) in 3T3-L1 adipocytes, outperforming pure HCA and garcinia extract. These results suggest that expandable konjac-based films are a viable and effective delivery system for herbal anti-obesity agents. Full article
(This article belongs to the Special Issue Advanced Polymeric Materials for Medical Applications)
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20 pages, 2096 KiB  
Article
Study of Total Ammoniacal Nitrogen Recovery Using Polymeric Thin-Film Composite Membranes for Continuous Operation of a Hybrid Membrane System
by Shirin Shahgodari, Joan Llorens and Jordi Labanda
Polymers 2025, 17(12), 1696; https://doi.org/10.3390/polym17121696 - 18 Jun 2025
Viewed by 324
Abstract
This study examined total ammoniacal nitrogen (TAN) rejection by two reverse osmosis (RO) and two nanofiltration (NF) membranes as a function of pH for three ammonium salts to optimize conditions for a hybrid membrane system that can produce high-purity TAN streams suitable for [...] Read more.
This study examined total ammoniacal nitrogen (TAN) rejection by two reverse osmosis (RO) and two nanofiltration (NF) membranes as a function of pH for three ammonium salts to optimize conditions for a hybrid membrane system that can produce high-purity TAN streams suitable for reuse. The results showed that TAN rejection was significantly influenced by membrane type, feed pH, and the ammonium salt used. This study represents the first attempt to simulate real manure wastewater conditions typically found in pig manure. TAN rejection for (NH4)2SO4 and NH4HCO3 reached up to 95% at pH values below 7, with the SW30 membrane showing the highest performance (99.5%), attributed to effective size exclusion and electrostatic repulsion of SO42− and HCO3− ions. In contrast, lower rejection was observed for NH4Cl, particularly with the MPF-34 membrane, due to its higher molecular weight cut-off (MWCO), which diminishes both exclusion mechanisms. TAN rejection decreased markedly with increasing pH across the BW30, NF90, and MPF-34 membranes as the proportion of uncharged NH3 increased. The lowest rejection rates (<15%) were recorded at pH 11.5 for both NF membranes. These results reveal a notable shift in separation behavior, where NH3 permeation under alkaline conditions becomes dominant over the commonly reported NH4+ retention at low pH. This novel insight offers a new perspective for optimizing membrane-based ammonia recovery in systems simulating realistic manure wastewater conditions. TAN recovery was evaluated using a hybrid membrane system, where NF membranes operated at high pH promoted NH3 permeation, and the SW30 membrane at pH 6.5 enabled TAN rejection as (NH4)2SO4. This hybrid system insight offers a new perspective for optimizing membrane-based ammonia recovery in systems simulating realistic manure wastewater conditions. Based on NH3 permeation and membrane characteristics, the NF90 membrane was operated at pH 9.5, achieving a TAN recovery of 48.3%, with a TAN concentration of 11.7 g/L, corresponding to 0.9% nitrogen. In contrast, the MPF-34 membrane was operated at pH 11.5. The NF90–SW30 system also achieved a TAN recovery of 48.3%, yielding 11.7 g/L of TAN with a nitrogen content of 1.22%. These nitrogen concentrations indicate that both retentate streams are suitable for use as liquid fertilizers in the form of (NH4)2SO4. A preliminary economic assessment estimated the chemical consumption cost at 0.586 EUR/kg and 0.729 EUR/kg of (NH4)2SO4 produced for the NF90–SW30 and MPF-34–SW30 systems, respectively. Full article
(This article belongs to the Special Issue Multifunctional Polymer Composite Materials, 2nd Edition)
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19 pages, 3134 KiB  
Article
Electrospinning of Miscanthus x giganteus Organosolv Lignin in Dimethyl Sulfoxide (DMSO)
by Roland Jacks Ekila, Tatjana Stevanovic and Denis Rodrigue
Polymers 2025, 17(12), 1695; https://doi.org/10.3390/polym17121695 - 18 Jun 2025
Viewed by 370
Abstract
Electrospinning is a simple technique to produce fibers with small diameters. These fibers can be made from different polymers, but the focus is now on biobased materials. In this work, the lignin obtained from Miscanthus x giganteus, an herbaceous plant, was isolated [...] Read more.
Electrospinning is a simple technique to produce fibers with small diameters. These fibers can be made from different polymers, but the focus is now on biobased materials. In this work, the lignin obtained from Miscanthus x giganteus, an herbaceous plant, was isolated by an Organosolv process leading to a high purity (90%), which is essential for its electrospinning. This lignin also had a carbon content of 72.2% with 24.8% oxygen and a low nitrogen content (1%). The isolated lignin was then solubilized in dimethyl sulfoxide (DMSO). Finally, an optimization step showed that a stable process was possible using a 62% lignin solution in DMSO with a needle-to-collector distance of 20 cm, a flow rate of 0.3 mL/h, a voltage of 25 kV, and a humidity of 35%. Nevertheless, lignin concentrations between 55 and 63% were studied to determine the effect of this parameter on the final fibers. A morphological analysis (SEM-EDX) enabled us to understand both the evolution of the diameter and the effect of dimethyl sulfoxide on the electrospun fibers. This study showed that electrospinning of the lignin obtained from Miscanthus x giganteus was possible, even without any additives. Full article
(This article belongs to the Collection Electrospun Nanofibers)
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14 pages, 2459 KiB  
Article
Molecular Level Understanding of Amine Structural Variations on Diaminodiphenyl Sulfone to Thermomechanical Characteristics in Bifunctional Epoxy Resin: Molecular Dynamics Simulation Approach
by Hei Je Jeong, Sung Hyun Kwon, Jihoon Lim, Woong Kwon, Gun Hwan Park, Eunhye Lee, Jong Sung Won, Man Young Lee, Euigyung Jeong and Seung Geol Lee
Polymers 2025, 17(12), 1694; https://doi.org/10.3390/polym17121694 - 18 Jun 2025
Viewed by 550
Abstract
Epoxy-based composite materials, widely used in various industries such as coatings, adhesives, aerospace, electronics, and biomedical engineering, remain a topic of global interest due to their varying characteristics based on the base resin and curing agents used. This paper employs molecular dynamics simulation [...] Read more.
Epoxy-based composite materials, widely used in various industries such as coatings, adhesives, aerospace, electronics, and biomedical engineering, remain a topic of global interest due to their varying characteristics based on the base resin and curing agents used. This paper employs molecular dynamics simulation to examine the thermal and mechanical properties, as well as molecular behaviors, of epoxy systems cured with diglycidyl ether of bisphenol F as the base resin and aromatic amine curing agents, specifically the meta structure of 3,3′-diaminodiphenyl sulfone (3,3′-DDS) and the para structure of 4,4′-diaminodiphenyl sulfone (4,4′-DDS). The 3,3′-DDS system demonstrated a greater density and Young’s modulus than the 4,4′-DDS system. This tendency was analyzed based on differences in molecular fractional free volume and cohesive energy density (CED). The 4,4′-DDS system exhibits a higher glass transition temperature (Tg) compared to the 3,3′-DDS system, with values of 406.36 K and 431.22 K, respectively. To understand this behavior, we examined atomic-scale displacements at Tg through mean squared displacement analysis, which revealed that the onset of molecular motion occurs at a lower temperature in the 3,3′-DDS system. Molecular-level study reveals how the structural features of each curing agent appear in thermal and mechanical properties, offering important insights for epoxy system development. Full article
(This article belongs to the Special Issue Structure and Dynamics of Polymers)
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17 pages, 8128 KiB  
Article
Tuning Polymer–Metal Interfaces via Solvent-Engineered Electroless Nickel Coatings on Functional Fibres
by Chenyao Wang, Heng Zhai, Xuzhao Liu, David Lewis, Yuhao Huang, Ling Ai, Xinyi Guan, Hugh Gong, Xuqing Liu and Anura Fernando
Polymers 2025, 17(12), 1693; https://doi.org/10.3390/polym17121693 - 18 Jun 2025
Viewed by 443
Abstract
Electroless nickel deposition (ELD) on polymer substrates enables the fabrication of flexible, conductive fibres for wearable and functional textiles. However, achieving uniform, low-defect coatings on synthetic fibres such as nylon-6,6 remains challenging due to their chemical inertness, hydrophobicity, and poor interfacial compatibility with [...] Read more.
Electroless nickel deposition (ELD) on polymer substrates enables the fabrication of flexible, conductive fibres for wearable and functional textiles. However, achieving uniform, low-defect coatings on synthetic fibres such as nylon-6,6 remains challenging due to their chemical inertness, hydrophobicity, and poor interfacial compatibility with metal coatings. This study presents a solvent-assisted approach using dimethyl sulfoxide (DMSO) in a conventional aqueous ELD bath to control both polymer–metal interfacial chemistry and nickel coating microstructure. The modified surface supports dense catalytic sites, triggering spatially uniform Ni nucleation. The combination of scanning electron microscopy and transmission electron microscopy confirms the difference in coarse grains with fully aqueous baths to a nanocrystalline shell with DMSO-modified baths. This refined microstructure relieves residual stress and anchors firmly to the swollen polymer, delivering +7 °C higher onset decomposition temperature and 45% lower creep strain at 50 °C compared with aqueous controls. The fabric strain sensor fabricated by 1 wt.% DMSO-modified ELD shows a remarkable sensitivity against strain, demonstrating a 1400% resistance change under 200% stain. Electrochemical impedance and polarisation tests confirm a two-fold rise in charge transfer resistance and negligible corrosion current drift after accelerated ageing. By clarifying how a polar aprotic co-solvent couples polymer swelling with metal growth kinetics, the study introduces a scalable strategy for tuning polymer–metal interfaces and advances solvent-assisted ELD as a route to mechanically robust, thermally stable, and corrosion-resistant conductive textiles. Full article
(This article belongs to the Special Issue Polymer Modification for Soft Matter and Flexible Devices)
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21 pages, 4674 KiB  
Article
Segmented Polyurethanes Based on Adipate and Sebacate Biodegradable Polyesters for Use as Nerve Guide Conduits in Peripheral Nerve Regeneration
by Alexis B. Sabido-Barahona, Rossana F. Vargas-Coronado, Fernando Hernández-Sánchez, Antonio Martínez-Richa, José L. Gómez Ribelles, Juan V. Cauich-Rodríguez and Angel Marcos-Fernández
Polymers 2025, 17(12), 1692; https://doi.org/10.3390/polym17121692 - 18 Jun 2025
Viewed by 470
Abstract
This study investigated the chemical, thermal, and mechanical properties of segmented polyurethanes (SPUs) synthesized using less common biodegradable polyester polyols, specifically poly(adipate) (PAD) and poly(sebacate) (PSC), to evaluate their potential as nerve guidance conduits (NGCs) in peripheral nerve regeneration. The synthesis of novel [...] Read more.
This study investigated the chemical, thermal, and mechanical properties of segmented polyurethanes (SPUs) synthesized using less common biodegradable polyester polyols, specifically poly(adipate) (PAD) and poly(sebacate) (PSC), to evaluate their potential as nerve guidance conduits (NGCs) in peripheral nerve regeneration. The synthesis of novel 4,4′ methylene-bis-cyclohexyl diisocyanate (HMDI) SPUs was conducted in a two-step process: prepolymer formation and chain extension with 1,4-butanediol (BO) or 1,4-butanediamine (BA). SPUs were synthesized with two molar ratios—polyol:HMDI:BA/BO at 1:2:1 and 1:3:2 for the PAD:HMDI:BA system—to optimize mechanical properties. 1HRMN analysis verified the expected chemical structure of SPUs, whereas Raman and IR spectroscopy confirmed successful polyurethane synthesis. X-ray diffractograms showed that PAD-based SPUs (SPUPAD) were amorphous while PSC-based SPUs (SPUPSC) exhibited semi-crystalline behavior. SPUPAD showed only one degradation stage by TGA, while DSC showed one thermal event. In contrast, SPUPSC exhibited two degradation stages and three thermal events that confirmed phase separation. The longitudinal tensile properties of an NGC fabricated from SPUA-PAD-2 (PAD:HMDI:BA (1:3:2)) after 30 days of immersion in water (25 °C) showed a lower modulus (4.46 ± 0.5 MPa) than native intact nerves (15.87 ± 2.21 MPa) but a similar modulus to extracted nerves (8.19 ± 7.27 MPa). This system exhibited a longitudinal tensile force of 11.1 ± 1.6 N, which is lower than that of peripheral nerves (19.85 ± 7.21 N) but higher than that of commercial collagen-based nerve guide conduits (6.89 ± 2.6 N). The observed properties suggest that PUA-PAD-2 has potential as a biomaterial for nerve regeneration applications. Full article
(This article belongs to the Special Issue Polymer Scaffold for Tissue Engineering Applications, 2nd Edition)
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36 pages, 4774 KiB  
Review
Exploring the Role of Advanced Composites and Biocomposites in Agricultural Machinery and Equipment: Insights into Design, Performance, and Sustainability
by Ehsan Fartash Naeimi, Kemal Çağatay Selvi and Nicoleta Ungureanu
Polymers 2025, 17(12), 1691; https://doi.org/10.3390/polym17121691 - 18 Jun 2025
Viewed by 745
Abstract
The agricultural sector faces growing pressure to enhance productivity and sustainability, prompting innovation in machinery design. Traditional materials such as steel still dominate but are a cause of increased weight, soil compaction, increased fuel consumption, and corrosion. Composite materials—and, more specifically, fiber-reinforced polymers [...] Read more.
The agricultural sector faces growing pressure to enhance productivity and sustainability, prompting innovation in machinery design. Traditional materials such as steel still dominate but are a cause of increased weight, soil compaction, increased fuel consumption, and corrosion. Composite materials—and, more specifically, fiber-reinforced polymers (FRPs)—offer appealing alternatives due to their high specific strength and stiffness, corrosion resistance, and design flexibility. Meanwhile, increasing environmental awareness has triggered interest in biocomposites, which contain natural fibers (e.g., flax, hemp, straw) and/or bio-based resins (e.g., PLA, biopolyesters), aligned with circular economy principles. This review offers a comprehensive overview of synthetic composites and biocomposites for agricultural machinery and equipment (AME). It briefly presents their fundamental constituents—fibers, matrices, and fillers—and recapitulates relevant mechanical and environmental properties. Key manufacturing processes such as hand lay-up, compression molding, resin transfer molding (RTM), pultrusion, and injection molding are discussed in terms of their applicability, benefits, and limits for the manufacture of AME. Current applications in tractors, sprayers, harvesters, and planters are covered in the article, with advantages such as lightweighting, corrosion resistance, flexibility and sustainability. Challenges are also reviewed, including the cost, repairability of damage, and end-of-life (EoL) issues for composites and the moisture sensitivity, performance variation, and standardization for biocomposites. Finally, principal research needs are outlined, including material development, long-term performance testing, sustainable and scalable production, recycling, and the development of industry-specific standards. This synthesis is a practical guide for researchers, engineers, and manufacturers who want to introduce innovative material solutions for more efficient, longer lasting, and more sustainable agricultural machinery. Full article
(This article belongs to the Special Issue Biopolymers for Food Packaging and Agricultural Applications)
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32 pages, 5511 KiB  
Article
Development of Carbohydrate Polyelectrolyte Nanoparticles for Use in Drug Delivery Systems that Cross the Blood–Brain Barrier to Treat Brain Tumors
by Vladimir E. Silant’ev, Mikhail E. Shmelev, Andrei S. Belousov, Fedor O. Trukhin, Nadezhda E. Struppul, Aleksandra A. Patlay, Anna K. Kravchenko, Sergey P. Shchava and Vadim V. Kumeiko
Polymers 2025, 17(12), 1690; https://doi.org/10.3390/polym17121690 - 18 Jun 2025
Viewed by 501
Abstract
The low effectiveness of various brain cancer treatment methods is due to a number of significant challenges. Most of them are unable to penetrate the blood–brain barrier (BBB) when drugs are administered systemically through the bloodstream. Nanoscale particles play a special role among [...] Read more.
The low effectiveness of various brain cancer treatment methods is due to a number of significant challenges. Most of them are unable to penetrate the blood–brain barrier (BBB) when drugs are administered systemically through the bloodstream. Nanoscale particles play a special role among materials capable of binding drug molecules and successfully crossing the BBB. Biopolymeric nanoparticles (NPs) demonstrate excellent biocompatibility and have the remarkable ability to modify the environment surrounding tumor cells, thereby potentially improving cellular uptake of delivery agents. In our research, nanoscale polyelectrolyte complexes (PECs) ranging in size from 56 to 209 nm were synthesized by ionic interaction of the oppositely charged polysaccharides pectin and chitosan. The structural characteristics of these complexes were carefully characterized by infrared (FTIR) and Raman spectroscopy. The immobilization efficiency of antitumor drugs was comprehensively evaluated using UV spectrophotometry. The cytotoxicity of the NPs was evaluated in the U87-MG cell line. The preliminary data indicate a significant decrease in the metabolic activity of these tumor cells. Important details on the interaction of the NPs with an endothelial layer structurally similar to the BBB were obtained by simulating the BBB using a model based on human blood vessels. Our studies allowed us to establish a significant correlation between the kinetic parameters of drug immobilization and the ratio of biopolymer concentrations in the initial compositions, which provides valuable information for future optimization of drug delivery system design. Full article
(This article belongs to the Special Issue Advanced Polymeric Biomaterials for Drug Delivery Applications)
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20 pages, 7657 KiB  
Article
Utilizing Excess Resin in Prepregs to Achieve Good Performance in Joining Hybrid Materials
by Nawres J. Al-Ramahi, Safaa M. Hassoni, Janis Varna and Roberts Joffe
Polymers 2025, 17(12), 1689; https://doi.org/10.3390/polym17121689 - 18 Jun 2025
Viewed by 432
Abstract
This study investigates the fracture toughness of adhesive joints between carbon fiber-reinforced polymer composites (CFRP) and boron-alloyed high-strength steel under Mode I and II loading, based on linear elastic fracture mechanics (LEFM). Two adhesive types were examined: the excess resin from the prepreg [...] Read more.
This study investigates the fracture toughness of adhesive joints between carbon fiber-reinforced polymer composites (CFRP) and boron-alloyed high-strength steel under Mode I and II loading, based on linear elastic fracture mechanics (LEFM). Two adhesive types were examined: the excess resin from the prepreg composite, forming a thin layer, and a toughened structural epoxy (Sika Power-533), designed for the automotive industry, forming a thick layer. Modified double cantilever beam (DCB) and end-notched flexure (ENF) specimens were used for testing. The results show that using Sika Power-533 increases the critical energy release rate by up to 30 times compared to the prepreg resin, highlighting the impact of adhesive layer thickness. Joints with the thick Sika adhesive performed similarly regardless of whether uncoated or Al–Si-coated steel was used, indicating the composite/Sika interface as the failure point. In contrast, the thin resin adhesive layer exhibited poor bonding with uncoated steel, which detached during sample preparation. This suggests that, for thin layers, the resin/steel interface is the weakest link. These findings underline the importance of adhesive selection and layer thickness for optimizing joint performance in composite–metal hybrid structures. Full article
(This article belongs to the Section Polymer Applications)
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14 pages, 3230 KiB  
Article
Encapsulation of Perfluoroalkyl Carboxylic Acids (PFCAs) Within Polymer Microspheres for Storage in Supercritical Carbon Dioxide: A Strategy Using Dispersion Polymerization of PFCA-Loaded Monomers
by Eri Yoshida
Polymers 2025, 17(12), 1688; https://doi.org/10.3390/polym17121688 - 17 Jun 2025
Viewed by 488
Abstract
The removal of per- and polyfluoroalkyl substances (PFAS) from global aquatic environments is an emerging issue. However, little attention has been paid to addressing accumulated PFAS through their removal. This study demonstrates the encapsulation of perfluoroalkyl carboxylic acids (PFCAs) within polymer microspheres that [...] Read more.
The removal of per- and polyfluoroalkyl substances (PFAS) from global aquatic environments is an emerging issue. However, little attention has been paid to addressing accumulated PFAS through their removal. This study demonstrates the encapsulation of perfluoroalkyl carboxylic acids (PFCAs) within polymer microspheres that dissolve in supercritical carbon dioxide (scCO2). PFCAs were effectively captured by a hindered amine-supported monomer, 2,2,6,6-tetramethyl-4-piperidyl methacrylate (TPMA), in methanol (MeOH) through a simple acid-base reaction. The PFCA-loaded TPMA underwent dispersion polymerization in MeOH in the presence of poly(N-vinylpyrrolidone) (PVP) as a surfactant, producing microspheres with high monomer conversions. The microsphere size depended on the molecular weight and concentration of PVP, as well as the perfluoroalkyl chain length of the PFCAs. X-ray photoelectron spectroscopy (XPS) revealed that the perfluoroalkyl chains migrated from the interior to the surface of the microspheres when exposed to air. These surface perfluoroalkyl chains facilitated dissolution of the microspheres in scCO2, with cloud points observed under relatively mild conditions. These findings suggest the potential for managing PFCA-encapsulated microspheres in the scCO2 phase deep underground via CO2 sequestration. Full article
(This article belongs to the Special Issue New Progress of Green Sustainable Polymer Materials)
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