Polymers

52 pages, 7563 KiB

Open AccessArticle

Design and Evaluation of a Inonotus obliquus–AgNP–Maltodextrin Delivery System: Antioxidant, Antimicrobial, Acetylcholinesterase Inhibitory and Cytotoxic Potential

by Ana-Maria Stanoiu, Cornelia Bejenaru, Adina-Elena Segneanu, Gabriela Vlase, Ionela Amalia Bradu, Titus Vlase, George Dan Mogoşanu, Maria Viorica Ciocîlteu, Andrei Biţă, Roxana Kostici, Dumitru-Daniel Herea and Ludovic Everard Bejenaru

Polymers 2025, 17(15), 2163; https://doi.org/10.3390/polym17152163 - 7 Aug 2025

Viewed by 304

Abstract

Inonotus obliquus, a medicinal mushroom valued for its bioactive compounds, has not been previously characterized from Romanian sources. This study presents the first comprehensive chemical and biological screening of I. obliquus, introducing novel polymer-based encapsulation systems to enhance the stability and [...] Read more.

Inonotus obliquus, a medicinal mushroom valued for its bioactive compounds, has not been previously characterized from Romanian sources. This study presents the first comprehensive chemical and biological screening of I. obliquus, introducing novel polymer-based encapsulation systems to enhance the stability and bioavailability of its bioactive constituents. Two distinct delivery systems were designed to enhance the functionality of I. obliquus extracts: (i) microencapsulation in maltodextrin (MIO) and (ii) a sequential approach involving preparation of silver nanoparticle-loaded I. obliquus (IO–AgNPs), followed by microencapsulation to yield the hybrid MIO–AgNP system. Comprehensive metabolite profiling using GC–MS and ESI–QTOF–MS revealed 142 bioactive constituents, including terpenoids, flavonoids, phenolic acids, amino acids, coumarins, styrylpyrones, fatty acids, and phytosterols. Structural integrity and successful encapsulation were confirmed by XRD, FTIR, and SEM analyses. Both IO–AgNPs and MIO–AgNPs demonstrated potent antioxidant activity, significant acetylcholinesterase inhibition, and robust antimicrobial effects against Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, and Escherichia coli. Cytotoxicity assays revealed pronounced activity against MCF-7, HCT116, and HeLa cell lines, with MIO–AgNPs exhibiting superior efficacy. The synergistic integration of maltodextrin and AgNPs enhanced compound stability and bioactivity. As the first report on Romanian I. obliquus, this study highlights its therapeutic potential and establishes polymer-based nanoencapsulation as an effective strategy for optimizing its applications in combating microbial resistance and cancer. Full article

(This article belongs to the Section Polymer Applications)

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15 pages, 4876 KiB

Open AccessArticle

Energy Absorption Characteristics of CFRP–Aluminum Foam Composite Structure Under High-Velocity Impact: Focusing on Varying Aspect Ratios and Relative Densities

by Jie Ren, Shujie Liu, Jiuhe Wang and Changfang Zhao

Polymers 2025, 17(15), 2162; https://doi.org/10.3390/polym17152162 - 7 Aug 2025

Viewed by 168

Abstract

This study systematically investigates the high-velocity impact response and energy absorption characteristics of carbon fiber-reinforced plastic (CFRP)—aluminum foam (AlF) hybrid composite structures, aiming to address the growing demand for lightweight yet high-performance energy-absorbing materials in aerospace and protective engineering applications. Particular emphasis is [...] Read more.

This study systematically investigates the high-velocity impact response and energy absorption characteristics of carbon fiber-reinforced plastic (CFRP)—aluminum foam (AlF) hybrid composite structures, aiming to address the growing demand for lightweight yet high-performance energy-absorbing materials in aerospace and protective engineering applications. Particular emphasis is placed on elucidating the influence of key geometric and material parameters, including the aspect ratio of the columns and the relative density of the AlF core. Experimental characterization was first performed using a split Hopkinson pressure bar (SHPB) apparatus to evaluate the dynamic compressive behavior of AlF specimens with four different relative densities (i.e., 0.163, 0.245, 0.374, and 0.437). A finite element (FE) model was then developed and rigorously validated against the experimental data, demonstrating excellent agreement in terms of deformation modes and force–displacement responses. Extensive parametric studies based on the validated FE framework revealed that the proposed CFRP-AlF composite structure achieves a balance between specific energy absorption (SEA) and peak crushing force, showing a significant improvement over conventional CFRP or AlF. The confinement effect of CFRP enables AlF to undergo progressive collapse along designated orientations, thereby endowing the CFRP-AlF composite structure with superior impact resistance. These findings provide critical insight for the design of next-generation lightweight protective structures subjected to extreme dynamic loading conditions. Full article

(This article belongs to the Special Issue Dynamic Behavior of Polymer Composite Materials and Structures, 2nd Edition)

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14 pages, 4543 KiB

Open AccessArticle

Tuning Corn Zein-Chitosan Biocomposites via Mild Alkaline Treatment: Structural and Physicochemical Property Insights

by Nagireddy Poluri, Creston Singer, David Salas-de la Cruz and Xiao Hu

Polymers 2025, 17(15), 2161; https://doi.org/10.3390/polym17152161 - 7 Aug 2025

Viewed by 142

Abstract

This study investigates the structural and functional enhancement of corn zein–chitosan composites via mild alkaline treatment to develop biodegradable protein-polysaccharide materials for diverse applications. Films with varying zein-to-chitosan ratios were fabricated and characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning [...] Read more.

This study investigates the structural and functional enhancement of corn zein–chitosan composites via mild alkaline treatment to develop biodegradable protein-polysaccharide materials for diverse applications. Films with varying zein-to-chitosan ratios were fabricated and characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Both untreated and sodium hydroxide (NaOH)-treated films were evaluated to assess changes in physicochemical properties. FTIR analysis revealed that NaOH treatment promoted deprotonation of chitosan’s amine groups, partial removal of ionic residues, and increased deacetylation, collectively enhancing hydrogen bonding and resulting in a denser molecular network. Simultaneously, partial unfolding of zein’s α-helical structures improved conformational flexibility and strengthened interactions with chitosan. These molecular-level changes led to improved thermal stability, reduced degradation, and the development of porous microstructures. Controlled NaOH treatment thus provides an effective strategy to tailor the physicochemical properties of zein–chitosan composite films, supporting their potential in sustainable food packaging, wound healing, and drug delivery applications. Full article

(This article belongs to the Section Biobased and Biodegradable Polymers)

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21 pages, 4965 KiB

Open AccessArticle

Recycling Continuous Glass Fibre-Reinforced Polyamide 6 Laminates via Compression Moulding

by Aditya Prakash Shembekar, Jason Yu, Mingfu Zhang, Chris Griffin and Dipa Ray

Polymers 2025, 17(15), 2160; https://doi.org/10.3390/polym17152160 - 7 Aug 2025

Viewed by 227

Abstract

End-of-life (EoL) continuous glass fibre-reinforced polyamide 6 composites (cGF/PA6) are commonly recycled by shredding and milling, followed by injection moulding, often resulting in lower mechanical properties of second-generation products, primarily due to fibre length reduction. This study investigates the thermomechanical reprocessing of cGF/PA6 [...] Read more.

End-of-life (EoL) continuous glass fibre-reinforced polyamide 6 composites (cGF/PA6) are commonly recycled by shredding and milling, followed by injection moulding, often resulting in lower mechanical properties of second-generation products, primarily due to fibre length reduction. This study investigates the thermomechanical reprocessing of cGF/PA6 laminates via compression moulding, aiming to retain maximum mechanical performance by preserving the fibre length. Two types of 2/2 twill glass fibre-reinforced anionically polymerised polyamide 6 laminates (cGF/APA6), with either a reactive sizing agent (RS) or a non-reactive sizing agent (nRS), were reprocessed at two different temperatures, i.e., at 180 °C (between the glass transition temperature (Tg) and the melting temperature (Tm) of PA6) and 230 °C (above the melting temperature (Tm) of PA6). The influence of reprocessing on matrix crystallinity, thermomechanical properties, microstructure, and flexural performance was investigated. The results revealed that reprocessing at both temperatures led to an improvement in matrix crystallinity, retention of the desirable α-crystalline phases, and an elevated T_g (glass transition temperature) in both reprocessed laminates. Additionally, reprocessing at 180 °C maintained the flexural performance in both, whereas reprocessing at 230 °C led to nearly 20% improvement in flexural strength for the RS laminate. The microstructural analysis of the failed flexural specimens showed matrix-coated fibre surfaces, highlighting retained fibre–matrix adhesion. Overall, the results offer insights into the potential of compression moulding as a viable alternative for recycling cGF/APA6 laminates. Full article

(This article belongs to the Section Circular and Green Sustainable Polymer Science)

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30 pages, 8202 KiB

Open AccessArticle

Structure and Texture Synergies in Fused Deposition Modeling (FDM) Polymers: A Comparative Evaluation of Tribological and Mechanical Properties

by Patricia Isabela Brăileanu, Marius-Teodor Mocanu, Tiberiu Gabriel Dobrescu, Nicoleta Elisabeta Pascu and Dan Dobrotă

Polymers 2025, 17(15), 2159; https://doi.org/10.3390/polym17152159 - 7 Aug 2025

Viewed by 232

Abstract

This study investigates the interplay between infill structure and surface texture in Fused Deposition Modeling (FDM)-printed polymer specimens and their combined influence on tribological and mechanical performance. Unlike previous works that focus on single-variable analysis, this work offers a comparative evaluation of Shore [...] Read more.

This study investigates the interplay between infill structure and surface texture in Fused Deposition Modeling (FDM)-printed polymer specimens and their combined influence on tribological and mechanical performance. Unlike previous works that focus on single-variable analysis, this work offers a comparative evaluation of Shore D hardness and coefficient of friction (COF) for PLA and Iglidur materials, incorporating diverse infill patterns. The results reveal that specific combinations (e.g., grid infill with 90% density) optimize hardness and minimize friction, offering practical insights for design optimization in functional parts. Our aim is to provide design insights for enhanced wear resistance and hardness through tailored structural configurations. Carbon Fiber-reinforced PLA (PLA CF), aramid fiber-reinforced Acrylonitrile Styrene Acrylate (Kevlar), and Iglidur I180-BL tribofilament. Disc specimens were fabricated with gyroid infill densities ranging from 10% to 100%. Experimental methodologies included Ball-on-Disc tests conducted under dry sliding conditions (5 N normal load, 150 mm/s sliding speed) to assess friction and wear characteristics. These tribological evaluations were complemented by profilometric and microscopic analyses and Shore D hardness testing. The results show that Iglidur I180-BL achieved the lowest friction coefficients (0.141–0.190) and negligible wear, while PLA specimens with 90% infill demonstrated a polishing-type wear with minimal material loss and a friction coefficient (COF) of ~0.108. In contrast, PLA CF and Kevlar exhibited higher wear depths (up to 154 µm for Kevlar) and abrasive mechanisms due to fiber detachment. Shore hardness values increased with infill density, with PLA reaching a maximum of 82.7 Shore D. These findings highlight the critical interplay between infill architecture and surface patterning and offer actionable guidelines for the functional design of durable FDM components in load-bearing or sliding applications. Full article

(This article belongs to the Collection Mechanical Behavior of Polymer-Based Materials)

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16 pages, 1192 KiB

Open AccessReview

The Use of Non-Degradable Polymer (Polyetheretherketone) in Personalized Orthopedics—Review Article

by Gabriela Wielgus, Wojciech Kajzer and Anita Kajzer

Polymers 2025, 17(15), 2158; https://doi.org/10.3390/polym17152158 - 7 Aug 2025

Viewed by 262

Abstract

Polyetheretherketone (PEEK) is a semi-crystalline thermoplastic polymer which, due to its very high mechanical properties and high chemical resistance, has found application in the automotive, aerospace, chemical, food and medical (biomedical engineering) industries. Owing to the use of additive technologies, particularly the Fused [...] Read more.

Polyetheretherketone (PEEK) is a semi-crystalline thermoplastic polymer which, due to its very high mechanical properties and high chemical resistance, has found application in the automotive, aerospace, chemical, food and medical (biomedical engineering) industries. Owing to the use of additive technologies, particularly the Fused Filament Fabrication (FFF) method, this material is the most widely used plastic to produce skull reconstruction implants, parts of dental implants and orthopedic implants, including spinal, knee and hip implants. PEEK enables the creation of personalized implants, which not only have greater elasticity compared to implants made of metal alloys but also resemble the physical properties of the cortical layer of human bone in terms of their mechanical properties. Therefore, the aim of this article is to characterize polyether ether ketone as an alternative material used in the manufacturing of implants in orthopedics and dentistry. Full article

(This article belongs to the Section Polymer Applications)

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27 pages, 4071 KiB

Open AccessArticle

Design and Development of a Sprayable Hydrogel Based on Thermo/pH Dual-Responsive Polymer Incorporating Azadirachta indica (Neem) Extract for Wound Dressing Applications

by Amlika Rungrod, Arthit Makarasen, Suwicha Patnin, Supanna Techasakul and Runglawan Somsunan

Polymers 2025, 17(15), 2157; https://doi.org/10.3390/polym17152157 - 7 Aug 2025

Viewed by 287

Abstract

Developing a rapidly gel-forming, in situ sprayable hydrogel with wound dressing functionality is essential for enhancing the wound healing process. In this study, a novel sprayable hydrogel-based wound dressing was developed by combining thermo- and pH- responsive polymers including Pluronic F127 (PF127) and [...] Read more.

Developing a rapidly gel-forming, in situ sprayable hydrogel with wound dressing functionality is essential for enhancing the wound healing process. In this study, a novel sprayable hydrogel-based wound dressing was developed by combining thermo- and pH- responsive polymers including Pluronic F127 (PF127) and N-succinyl chitosan (NSC). NSC was prepared by modifying chitosan with succinic anhydride, as confirmed by Fourier-transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The NSC synthesized using a succinic anhydride-to-chitosan molar ratio of 5:1 exhibited the highest degree of substitution, resulting in a water-soluble polymer effective over a broad pH range. The formulation process of the PF127:NSC sprayable hydrogel was optimized and evaluated based on its sol–gel phase transition behavior, clarity, gelation time, liquid and moisture management, stability, and cytotoxicity. These properties can be suitably tailored by adjusting the concentrations of PF127 and NSC. Moreover, the antioxidant capacity of the hydrogels was enhanced by incorporating Azadirachta indica (neem) extract, a bioactive compound, into the optimized sprayable hydrogel. Both neem release and antioxidant activity increased in a dose-dependent manner. Overall, the developed sprayable hydrogel exhibited favorable sprayability, appropriate gelation properties, controlled drug release, and antioxidant activity, underscoring its promising translational potential as a wound dressing. Full article

(This article belongs to the Special Issue Innovations in Hydrogel Design for Pharmaceutical and Medical Applications)

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23 pages, 6941 KiB

Open AccessArticle

Isolation and Characterization of Lignin from Sapele (Entandrophragma cylindricum): Application in Flexible Polyurethane Foam Production

by Hubert Justin Nnanga Guissele, Arnaud Maxime Cheumani Yona, Armel Edwige Mewoli, Désiré Chimeni-Yomeni, Lucioni Fabien Tsague, Tatiane Marina Abo, Jean-Bosco Saha-Tchinda, Maurice Kor Ndikontar and Antonio Pizzi

Polymers 2025, 17(15), 2156; https://doi.org/10.3390/polym17152156 - 6 Aug 2025

Viewed by 292

Abstract

Lignin used in this work was isolated from sapele (Entandrophragma cylindricum) wood through a hybrid pulping process using soda/ethanol as pulping liquor and denoted soda-oxyethylated lignin (SOL). SOL was mixed with a polyethylene glycol (PEG)–glycerol mixture (80/20 v/v) [...] Read more.

Lignin used in this work was isolated from sapele (Entandrophragma cylindricum) wood through a hybrid pulping process using soda/ethanol as pulping liquor and denoted soda-oxyethylated lignin (SOL). SOL was mixed with a polyethylene glycol (PEG)–glycerol mixture (80/20 v/v) as liquefying solvent with 98% wt. sulfur acid as catalyst, and the mixture was taken to boil at 140 °C for 2, 2.5, and 3 h. Three bio-polyols LBP1, LBP2, and LBP3 were obtained, and each of them exhibited a high proportion of -OH groups. Lignin-based polyurethane foams (LBPUFs) were prepared using the bio-polyols obtained with a toluene diisocyanate (TDI) prepolymer by the one-shot method. Gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and carbon-13 nuclear magnetic resonance spectroscopy (¹³C NMR) were used characterize lignin in order to determine viscosity, yield, and composition and to characterize their structure. The PEG-400–glycerol mixture was found to react with the lignin bio-polyols’ phenolic -OHs. The bio-polyols’ viscosity was found to increase as the liquefaction temperature increased, while simultaneously their molecular weights decreased. All the NCO groups were eliminated from the samples, which had high thermal stability as the liquefaction temperature increased, leading to a decrease in cell size, density, and crystallinity and an improvement in mechanical performance. Based on these properties, especially the presence of some aromatic rings in the bio-polyols, the foams produced can be useful in automotive applications and for floor carpets. Full article

(This article belongs to the Section Circular and Green Sustainable Polymer Science)

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13 pages, 1043 KiB

Open AccessArticle

Color-Dependent Polymerization: The Impact of Curing Time on the Conversion Degree and Microhardness of Colored Compomers

by Ozgul Carti Dorterler, Fatma Yilmaz and Ozge Tokul Olmez

Polymers 2025, 17(15), 2155; https://doi.org/10.3390/polym17152155 - 6 Aug 2025

Viewed by 169

Abstract

This study investigated the effects of color shade and curing time on the degree of conversion (DC) and microhardness of colored compomers. A total of 162 samples (81 for DC, 81 for microhardness) were prepared, with nine samples per color group (gold, blackberry, [...] Read more.

This study investigated the effects of color shade and curing time on the degree of conversion (DC) and microhardness of colored compomers. A total of 162 samples (81 for DC, 81 for microhardness) were prepared, with nine samples per color group (gold, blackberry, green, pink, orange, lemon, blue, silver) and for the control. Samples were subdivided into three polymerization subgroups (3 s/3200 mW/cm², 10 s/1000 mW/cm², 20 s/1000 mW/cm²). The DC was analyzed via fourier transform infrared spectroscopy (FTIR) and microhardness was measured using Vickers testing. Statistical analysis included two-way ANOVA and Spearman correlation (α = 0.05). The colored compomers demonstrated a significantly lower DC compared to the control group (p ≤ 0.001). Among the tested colors, green exhibited the lowest DC (33.3%), while orange showed the highest (51.0%). A significant difference in DC was observed across curing times (p = 0.005), with the 3 s and 20 s groups exhibiting significantly higher conversion rates than the 10 s group. Microhardness values exhibited significant variation depending on the color (p < 0.001). Gold compomers demonstrated the lowest microhardness, whereas silver compomers showed comparable performance with the control group (p = 0.154). A moderate correlation between DC and microhardness was observed overall (ρ = 0.42, p = 0.003). However, the observed relationships were color-dependent: orange displayed a strong positive correlation (ρ = 0.78), whereas pink revealed no meaningful association (ρ = −0.15). Color and curing time critically influence compomer performance. High-intensity short curing is viable for lighter colors, while darker colors require extended curing. Customized protocols are essential to optimize clinical outcomes in pediatric dentistry. Full article

(This article belongs to the Section Polymer Analysis and Characterization)

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18 pages, 5831 KiB

Open AccessArticle

Cure Kinetics-Driven Compression Molding of CFRP for Fast and Low-Cost Manufacturing

by Xintong Wu, Ming Zhang, Zhongling Liu, Xin Fu, Haonan Liu, Yuchen Zhang and Xiaobo Yang

Polymers 2025, 17(15), 2154; https://doi.org/10.3390/polym17152154 - 6 Aug 2025

Viewed by 261

Abstract

Carbon fiber-reinforced polymer (CFRP) composites are widely used in aerospace due to their excellent strength-to-weight ratio and tailorable properties. However, these properties critically depend on the CFRP curing cycle. The commonly adopted manufacturer-recommended curing cycle (MRCC), designed to accommodate the most conservative conditions, [...] Read more.

Carbon fiber-reinforced polymer (CFRP) composites are widely used in aerospace due to their excellent strength-to-weight ratio and tailorable properties. However, these properties critically depend on the CFRP curing cycle. The commonly adopted manufacturer-recommended curing cycle (MRCC), designed to accommodate the most conservative conditions, involves prolonged curing times and high energy consumption. To overcome these limitations, this study proposes an efficient and adaptable method to determine the optimal curing cycle. The effects of varying heating rates on resin dynamic and isothermal–exothermic behavior were characterized via reaction kinetics analysis using differential scanning calorimetry (DSC) and rheological measurements. The activation energy of the reaction system was substituted into the modified Sun–Gang model, and the parameters were estimated using a particle swarm optimization algorithm. Based on the curing kinetic behavior of the resin, CFRP compression molding process orthogonal experiments were conducted. A weighted scoring system incorporating strength, energy consumption, and cycle time enabled multidimensional evaluation of optimized solutions. Applying this curing cycle optimization method to a commercial epoxy resin increased efficiency by 247.22% and reduced energy consumption by 35.7% while meeting general product performance requirements. These results confirm the method’s reliability and its significance for improving production efficiency. Full article

(This article belongs to the Special Issue Advances in High-Performance Polymer Materials, 2nd Edition)

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14 pages, 4016 KiB

Open AccessArticle

Failure Mechanism of Pre-Stressed CFRP Beam Under Laser Ablation

by Yuting Zhao, Ruokun Zhang and Zhuhua Tan

Polymers 2025, 17(15), 2153; https://doi.org/10.3390/polym17152153 - 6 Aug 2025

Viewed by 192

Abstract

This paper focuses on the failure mechanism of a pre-stressed CFRP cantilever beam under laser ablation. During testing, a mass was applied to the CFRP cantilever beam to achieve a pre-stressed state, and the laser power densities varied from 500 to 1500 W·cm [...] Read more.

This paper focuses on the failure mechanism of a pre-stressed CFRP cantilever beam under laser ablation. During testing, a mass was applied to the CFRP cantilever beam to achieve a pre-stressed state, and the laser power densities varied from 500 to 1500 W·cm⁻². Corresponding scanning electron microscope (SEM) tests were also performed on the ablation zone and fracture surface to analyze the failure mechanism. The results showed that the CFRP beam failed in compression at the bottom surface, which was due to a decrease in local stiffness and strength caused by heat softening, rather than by ablation damage on the top surface. The failure time decreased from 19.64 s to 6.52 s as the power density (500–1500 W·cm⁻²) and pre-stress loading (300–750 N·cm) increased, indicating that pre-stress loading has a more significant influence on the failure time of CFRP beams compared to power density. Full article

(This article belongs to the Topic Advanced Carbon Fiber Reinforced Composite Materials, Volume II)

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13 pages, 2130 KiB

Open AccessArticle

Controllable Structure and Fluorescence Enhancement of ACQ Dye Nanoparticles Based on the FNP Process

by Yue Wu, Yutao Zhang, Zhiqian Guo and Yisheng Xu

Polymers 2025, 17(15), 2152; https://doi.org/10.3390/polym17152152 - 6 Aug 2025

Viewed by 221

Abstract

Fluorescent dyes, such as cyanine dyes, are widely used in fluorescence-imaging-guided tumor therapy due to their high absorbance and fluorescence quantum yield. However, challenges persist in optimizing the performance of fluorescent nanoparticles, particularly due to the aggregation-caused quenching (ACQ) effect of cyanine dyes. [...] Read more.

Fluorescent dyes, such as cyanine dyes, are widely used in fluorescence-imaging-guided tumor therapy due to their high absorbance and fluorescence quantum yield. However, challenges persist in optimizing the performance of fluorescent nanoparticles, particularly due to the aggregation-caused quenching (ACQ) effect of cyanine dyes. Here, a novel counterion construction strategy is introduced using cyanine dye as a model ACQ dye. Through dynamic-controlled flash nanoprecipitation, fluorescent nanoparticles (CyINPs) with tunable structures are developed, investigating the effects of various factors, including counterions, block copolymers, and dye concentrations, on CyINPs’ stability and fluorescence enhancement. The optimized CyINPs with good water solubility show a 21-fold increase in fluorescence intensity and a 3.5-fold increase in encapsulation efficiency compared to CyINPs prepared by a thermodynamic-driven method. Under the efforts of polymers and counterions, dyes are separated, which reduces the impact of the ACQ effect and results in stronger fluorescence intensity, providing insights into improving nanoparticle biocompatibility and energy utilization efficiency. Full article

(This article belongs to the Section Polymer Applications)

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16 pages, 1674 KiB

Open AccessArticle

Enhanced Anticancer Activity of Atractylodin-Loaded Poly(lactic-co-glycolic Acid) Nanoparticles Against Cholangiocarcinoma

by Tullayakorn Plengsuriyakarn, Luxsana Panrit and Kesara Na-Bangchang

Polymers 2025, 17(15), 2151; https://doi.org/10.3390/polym17152151 - 6 Aug 2025

Viewed by 220

Abstract

Cholangiocarcinoma (CCA) is highly prevalent in the Greater Mekong sub-region, especially northeastern Thailand, where infection with the liver fluke Opisthorchis viverrini is a major etiological factor. Limited therapeutic options and the absence of reliable early diagnosis tools impede effective disease control. Atractylodes lancea [...] Read more.

Cholangiocarcinoma (CCA) is highly prevalent in the Greater Mekong sub-region, especially northeastern Thailand, where infection with the liver fluke Opisthorchis viverrini is a major etiological factor. Limited therapeutic options and the absence of reliable early diagnosis tools impede effective disease control. Atractylodes lancea (Thunb.) DC.—long used in Thai and East Asian medicine, contains atractylodin (ATD), a potent bioactive compound with anticancer potential. Here, we developed ATD-loaded poly(lactic co-glycolic acid) nanoparticles (ATD PLGA NPs) and evaluated their antitumor efficacy against CCA. The formulated nanoparticles had a mean diameter of 229.8 nm, an encapsulation efficiency of 83%, and exhibited biphasic, sustained release, reaching a cumulative release of 92% within seven days. In vitro, ATD-PLGA NPs selectively reduced the viability of CL-6 and HuCCT-1 CCA cell lines, with selectivity indices (SI) of 3.53 and 2.61, respectively, outperforming free ATD and 5-fluorouracil (5-FU). They suppressed CL-6 cell migration and invasion by up to 90% within 12 h and induced apoptosis in 83% of cells through caspase-3/7 activation. Micronucleus assays showed lower mutagenic potential than the positive control. In vivo, ATD-PLGA NPs dose-dependently inhibited tumor growth and prolonged survival in CCA-xenografted nude mice; the high-dose regimen matched or exceeded the efficacy of 5-FU. Gene expression analysis revealed significant downregulation of pro-tumorigenic factors (VEGF, MMP-9, TGF-β, TNF-α, COX-2, PGE₂, and IL-6) and upregulation of the anti-inflammatory cytokine IL-10. Collectively, these results indicate that ATD-PLGA NPs are a promising nanotherapeutic platform for targeted CCA treatment, offering improved anticancer potency, selectivity, and safety compared to conventional therapies. Full article

(This article belongs to the Section Polymer Applications)

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32 pages, 5531 KiB

Open AccessReview

Polyethylenimine Carriers for Drug and Gene Delivery

by Ahmed Ismail and Shih-Feng Chou

Polymers 2025, 17(15), 2150; https://doi.org/10.3390/polym17152150 - 6 Aug 2025

Viewed by 281

Abstract

Polyethylenimine (PEI) is a cationic polymer with a high density of amine groups suitable for strong electrostatic interactions with biological molecules to preserve their bioactivities during encapsulation and after delivery for biomedical applications. This review provides a comprehensive overview of PEI as a [...] Read more.

Polyethylenimine (PEI) is a cationic polymer with a high density of amine groups suitable for strong electrostatic interactions with biological molecules to preserve their bioactivities during encapsulation and after delivery for biomedical applications. This review provides a comprehensive overview of PEI as a drug and gene carrier, describing its polymerization methods in both linear and branched forms while highlighting the processing methods to manufacture PEIs into drug carriers, such as nanoparticles, coatings, nanofibers, hydrogels, and films. These various PEI carriers enable applications in non-viral gene and small molecule drug deliveries. The structure–property relationships of PEI carriers are discussed with emphasis on how molecular weights, branching degrees, and surface modifications of PEI carriers impact biocompatibility, transfection efficiency, and cellular interactions. While PEI offers remarkable potential for drug and gene delivery, its clinical translation remains limited by challenges, including cytotoxicity, non-degradability, and serum instability. Our aim is to provide an understanding of PEI and the structure–property relationships of its carrier forms to inform future research directions that may enable safe and effective clinical use of PEI carriers for drug and gene delivery. Full article

(This article belongs to the Special Issue Biocompatible and Biodegradable Polymer Materials)

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14 pages, 5990 KiB

Open AccessArticle

Distinctive Features of the Buffer Capacity of Polyelectrolyte Microcapsules Formed on MnCO₃ Core

by Aleksandr L. Kim, Alexey V. Dubrovskii and Sergey A. Tikhonenko

Polymers 2025, 17(15), 2149; https://doi.org/10.3390/polym17152149 - 6 Aug 2025

Viewed by 203

Abstract

The development of layer-by-layer polyelectrolyte microcapsules (PMCs) with defined buffer capacity (BC) is a key task for creating stable systems in biomedicine and materials science. Manganese carbonate (MnCO₃), which shares properties with CaCO₃ and the ability to form hollow structures, [...] Read more.

The development of layer-by-layer polyelectrolyte microcapsules (PMCs) with defined buffer capacity (BC) is a key task for creating stable systems in biomedicine and materials science. Manganese carbonate (MnCO₃), which shares properties with CaCO₃ and the ability to form hollow structures, represents a promising alternative. However, its interaction with polyelectrolytes and its influence on BC remain insufficiently studied. This research focuses on determining the BC of PMCs templated on MnCO₃ cores under varying ionic strength (0.22–3 M NaCl) and temperature (60–90 °C), as well as comparing the results with PMCs templated on CaCO₃ and PS cores. It was found that MnCO₃-based PMCs (PMC_Mn) exhibit hybrid behavior between CaCO₃- and PS-based PMCs: the BC dynamics of PMC_Mn and CaCO₃-based PMCs (PMC_Ca) in water are identical. At different ionic strength at pH < 5, the BC of PMCMn and PS-based PMCs (PMC_PS) remains unchanged, while at pH > 8.5, the BC of PMC_Mn increases only at 3 M NaCl. The BC of PMC_Mn remains stable under heating, whereas the BC of PMC_Ca and PMC_PS decreases. These results confirm that the choice of core material dictates PMC functionality, paving the way for adaptive systems in biosensing and controlled drug delivery. Full article

(This article belongs to the Special Issue Stimuli-Responsive Polymers: Advances and Prospects)

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19 pages, 4563 KiB

Open AccessArticle

Designing Imidazolium-Mediated Polymer Electrolytes for Lithium-Ion Batteries Using Machine-Learning Approaches: An Insight into Ionene Materials

by Ghazal Piroozi and Irshad Kammakakam

Polymers 2025, 17(15), 2148; https://doi.org/10.3390/polym17152148 - 6 Aug 2025

Viewed by 320

Abstract

Over the past few decades, lithium-ion batteries (LIBs) have gained significant attention due to their inherent potential for environmental sustainability and unparalleled energy storage efficiency. Meanwhile, polymer electrolytes have gained popularity in several fields due to their ability to adapt to various battery [...] Read more.

Over the past few decades, lithium-ion batteries (LIBs) have gained significant attention due to their inherent potential for environmental sustainability and unparalleled energy storage efficiency. Meanwhile, polymer electrolytes have gained popularity in several fields due to their ability to adapt to various battery geometries, enhanced safety features, greater thermal stability, and effectiveness in reducing dendrite growth on the anode. However, their relatively low ionic conductivity compared to liquid electrolytes has limited their application in high-performance devices. This limitation has led to recent studies revolving around the development of poly(ionic liquids) (PILs), particularly imidazolium-mediated polymer backbones as novel electrolyte materials, which can increase the conductivity with fine-tuning structural benefits, while maintaining the advantages of both solid and gel electrolytes. In this study, a curated dataset of 120 data points representing eight different polymers was used to predict ionic conductivity in imidazolium-based PILs as well as the emerging ionene substructures. For this purpose, four ML models: CatBoost, Random Forest, XGBoost, and LightGBM were employed by incorporating chemical structure and temperature as the models’ inputs. The best-performing model was further employed to estimate the conductivity of novel ionenes, offering insights into the potential of advanced polymer architectures for next-generation LIB electrolytes. This approach provides a cost-effective and intelligent pathway to accelerate the design of high-performance electrolyte materials. Full article

(This article belongs to the Special Issue Artificial Intelligence in Polymers)

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16 pages, 2029 KiB

Open AccessArticle

Multi-Objective Optimization of Biodegradable and Recyclable Composite PLA/PHA Parts

by Burak Kisin, Mehmet Kivanc Turan and Fatih Karpat

Polymers 2025, 17(15), 2147; https://doi.org/10.3390/polym17152147 - 6 Aug 2025

Viewed by 266

Abstract

Additive manufacturing (AM) techniques, especially fused deposition modeling (FDM), offer significant advantages in terms of cost, material efficiency, and design flexibility. In this study, the mechanical performance of biodegradable PLA/PHA composite samples produced via FDM was optimized by evaluating the influence of key [...] Read more.

Additive manufacturing (AM) techniques, especially fused deposition modeling (FDM), offer significant advantages in terms of cost, material efficiency, and design flexibility. In this study, the mechanical performance of biodegradable PLA/PHA composite samples produced via FDM was optimized by evaluating the influence of key printing parameters—layer height, printing orientation, and printing speed—on both the tensile and compressive strength. A full factorial design (3 × 3 × 3) was employed, and all of the samples were triplicated to ensure the consistency of the results. Grey relational analysis (GRA) was used as a multi-objective optimization method to determine the optimal parameter combinations. An analysis of variance (ANOVA) was also conducted to assess the statistical significance of each parameter. The ANOVA results revealed that printing orientation is the most significant parameter for both tensile and compression strength. The optimal parameter combination for maximizing mechanical properties was a layer height of 0.1 mm, an X printing orientation, and a printing speed of 50 mm/s. This study demonstrates the effectiveness of GRA in optimizing the mechanical properties of biodegradable composites and provides practical guidelines to produce environmentally sustainable polymer parts. Full article

(This article belongs to the Special Issue Sustainable Bio-Based and Circular Polymers and Composites)

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19 pages, 1494 KiB

Open AccessArticle

Development of Biodegradable Foam Trays from Brewer’s Malt Bagasse and Potato Residues from Agricultural Crops

by Evelyn F. Vásquez-Bacilio, Cesar I. Mejia-Llontop, Carlos E. Tirado-Rodríguez, María de Fátima Arévalo-Oliva, Beetthssy Z. Hurtado-Soria, Eudes Villanueva, Gilbert Rodriguez, Delia Rita Tapia-Blácido and Elza Aguirre

Polymers 2025, 17(15), 2146; https://doi.org/10.3390/polym17152146 - 6 Aug 2025

Viewed by 384

Abstract

In light of the environmental impact of disposable products made from petroleum-based plastics, this study focused on developing biodegradable foam trays made from a starch (PS) derived from potato waste and beer malt flour (BMBF). The objective of this study was to evaluate [...] Read more.

In light of the environmental impact of disposable products made from petroleum-based plastics, this study focused on developing biodegradable foam trays made from a starch (PS) derived from potato waste and beer malt flour (BMBF). The objective of this study was to evaluate the effect of the concentration of BMBF on the physical and mechanical properties of potato starch-based foam trays prepared by the thermoforming process at temperatures of 150 °C (upper plate) and 145 °C (lower plate) for 5 min and 40 s. The results showed that increasing the BMBF concentration from 0 to 40% reduced the moisture content from 4.68% to 3.42%, increased the thickness from 2.63 cm to 4.77 cm, and decreased the density from 0.28 g.cm⁻³ to 0.15 g.cm⁻³. Meanwhile, the water absorption capacity increased from 38.7% to 69.7%. In terms of mechanical properties, increasing the BMBF concentration in the PS foam tray resulted in a decrease in hardness from 5.61 N to 2.87 N, a decrease in tensile strength from 2.92 MPa to 0.85 MPa, and a decrease in elongation from 1.42% to 0.59%. Meanwhile, fracturability increased from 2.04 mm to 3.68 mm. FTIR analysis revealed interactions between BMBF and PS in the composite foam tray. Thermogravimetric analysis (TGA) showed two thermal events: one between 20.96 °C and 172.89 °C, and another between 189.14 °C and 517.69 °C, with weight losses of 5.53% and 74.23%, leaving an ash residue of 20.24%. Differential calorimetry analysis (DSC) showed a glass transition at 152.88 °C and a melting at 185.94 °C, with an enthalpy of fusion of 74.11 J.g⁻¹. Higher concentrations of BMBF (>10%) decreased the water resistance, mechanical strength, and flexibility of the PS foam trays. Therefore, a formulation of 90% PS and 10% BMBF was better for producing a foam tray with improved mechanical properties and water resistance, which could be used as a sustainable alternative to conventional single-use plastic. Full article

(This article belongs to the Section Biobased and Biodegradable Polymers)

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15 pages, 961 KiB

Open AccessArticle

Analysis of Chemical Composition and Odor Characteristics in Particleboards Decorated by Resin-Impregnated Paper, Polypropylene Film and Polyvinyl Chloride Film

by Liming Zhu, Minghui Yang, Lina Tang, Qian Chen, Xiaorui Liu, Xianwu Zou, Yuejin Fu and Bo Liu

Polymers 2025, 17(15), 2145; https://doi.org/10.3390/polym17152145 - 5 Aug 2025

Viewed by 196

Abstract

Analysis of changes in TVOC and VOCs chemical composition or odor characteristics of particleboard before and after decoration treatment with resin-impregnated paper (RIP), polypropylene (PP) film and polyvinyl chloride (PVC) film were studied. The effects of these three decoration treatments on masking or [...] Read more.

Analysis of changes in TVOC and VOCs chemical composition or odor characteristics of particleboard before and after decoration treatment with resin-impregnated paper (RIP), polypropylene (PP) film and polyvinyl chloride (PVC) film were studied. The effects of these three decoration treatments on masking or suppressing the release of VOCs and odorants from particleboard were explored. The substances that were covered or suppressed and newly introduced before and after processing were identified to provide a basis for reducing the odor emissions of PVC-, PP- and RIP-decorated particleboard. Taking undecorated particleboard and particleboard treated by three types of decorative materials as research subjects, the air permeability of the three decorative materials was tested using the Gurley Permeability Tester. TVOC emissions from the boards were evaluated using the 1 m³ environmental chamber method. Qualitative and quantitative analyses of the samples were conducted via thermal desorption–gas chromatography–mass spectrometry (TD-GCMS). The contribution of odor substances was determined using odor activity value (OAV). The results indicated that the permeability from high to low was PVC film, PP film and RIP. Compared with undecorated particleboard, the TVOC emissions of PVC-decorated boards decreased by 93%, PP-decorated particleboard by 83% but the TVOC emissions of RIP-decorated particleboard increased by 67%. PP decoration treatment masked or suppressed the release of 20 odor substances but introduced xylene, which can increase potentially the health risks for PP-decorated particleboard. PVC decoration treatment masked or suppressed 19 odor substances, but it introduced 12 new compounds, resulting in an overall increase in TVOC emissions. RIP treatment did not introduce new odor substances. After PP film and RIP treatments, both the variety of VOCs released and the number of key odor-contributing compounds and modifying odorants decreased. In contrast, the number of modifying odorants and potential odorants increased after PVC treatment. VOC emissions were effectively masked or suppressed by three decoration treatments, same as the release of substances contributing to overall odor of particleboard was reduced. Among them, PP and RIP decorative materials demonstrate better effects. Full article

(This article belongs to the Special Issue Eco-Friendly Supramolecular Polymeric Materials, 2nd Edition)

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26 pages, 10877 KiB

Open AccessArticle

Analysis of Mechanical Properties of Crumb Rubber Tires Mixed with Silty Sand of Various Sizes and Percentages

by Sindambiwe Theogene, Jianxiu Sun, Yanzi Wang, Run Xu, Jie Sun, Yuchen Tao, Changyong Zhang, Qingshuo Sun, Jiandong Wu, Hongya Yue and Hongbo Zhang

Polymers 2025, 17(15), 2144; https://doi.org/10.3390/polym17152144 - 5 Aug 2025

Viewed by 332

Abstract

Every year, a billion tires are discarded worldwide, with only a small percentage being recycled. This leads to significant environmental hazards, such as fire risks and improper disposal. Silty sand also presents technical challenges due to its poor shear strength, susceptibility to erosion, [...] Read more.

Every year, a billion tires are discarded worldwide, with only a small percentage being recycled. This leads to significant environmental hazards, such as fire risks and improper disposal. Silty sand also presents technical challenges due to its poor shear strength, susceptibility to erosion, and low permeability. This study explores the incorporation of crumb rubber derived from waste tires into silty sand to enhance its mechanical properties. Crumb rubber particles of varying sizes (3–6 mm, 5–10 mm, and 10–20 mm) were mixed with silty sand at 0%, 3%, 6%, and 9% percentages, respectively. Triaxial compression tests of unconsolidated and consolidated undrained tests with cell pressures of 100, 300, and 500 kPa were conducted. The deviatoric stress, shear stress, and stiffness modulus were investigated. The results revealed that the addition of crumb rubber significantly increased the deviatoric and shear stresses, especially at particle sizes of 5–10 mm, with contents of 3%, 6%, and 9%. Additionally, the stiffness modulus was notably reduced in the mixture containing 6% crumb rubber tire. These findings suggest that incorporating crumb rubber tires into silty sand not only improves silty sand performance but also offers an environmentally sustainable approach to tire waste recycling, making it a viable strategy for silty sand stabilization in construction and geotechnical engineering performance. Full article

(This article belongs to the Section Polymer Analysis and Characterization)

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19 pages, 6687 KiB

Open AccessArticle

Comparison of Elastic Modulus Calculations in ASTM D7205 and CSA S806 for CFRP Rebar Under Elevated Temperature

by Seung-Beom Kang, Dae-Hee Kang and Wonchang Choi

Polymers 2025, 17(15), 2143; https://doi.org/10.3390/polym17152143 - 5 Aug 2025

Viewed by 238

Abstract

In this study, the elastic modulus of CFRP rebars under high-temperature conditions was evaluated in accordance with ASTM D7205 and CSA S806, and the differences between the two standards were compared and analyzed. CFRP rebars with diameters of 10 mm and 13 mm [...] Read more.

In this study, the elastic modulus of CFRP rebars under high-temperature conditions was evaluated in accordance with ASTM D7205 and CSA S806, and the differences between the two standards were compared and analyzed. CFRP rebars with diameters of 10 mm and 13 mm were tested, and tensile specimens were prepared following the procedures specified in both standards. Tensile tests were conducted at temperatures ranging from 25 °C to 650 °C using an electric furnace. Fracture morphology before and after testing, as well as microstructural changes, were examined through scanning electron microscopy (SEM). The results revealed that the ASTM standard determines the elastic modulus based on the initial linear portion of the stress–strain curve before the transition point, whereas the CSA standard includes the post-transition segment. At temperatures below 325 °C, the ASTM-derived modulus exhibited a lower coefficient of variation (COV) compared to the CSA-derived values, indicating a more stable performance. By applying the experimentally obtained modulus values to various prediction models, the model with the lowest average error was identified. These findings confirm that the elastic modulus of CFRP rebars can be reasonably predicted under elevated-temperature conditions using calibrated models. Full article

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18 pages, 1289 KiB

Open AccessArticle

Novel Film-Forming Spray: Advancing Shelf Life Extension and Post-Harvest Loss Reduction in Eggs

by Nagesh Sonale, Rokade J. Jaydip, Akhilesh Kumar, Monika Madheswaran, Rohit Kumar, Prasad Wadajkar and Ashok Kumar Tiwari

Polymers 2025, 17(15), 2142; https://doi.org/10.3390/polym17152142 - 5 Aug 2025

Viewed by 319

Abstract

This study explores the development of a topical film-forming spray infused with phytobiotic herbs to extend egg shelf life and maintain its quality. Unlike traditional surface treatments, film-forming sprays provide uniform drug distribution, better bioavailability, effective CO₂ retention by sealing pores, and [...] Read more.

This study explores the development of a topical film-forming spray infused with phytobiotic herbs to extend egg shelf life and maintain its quality. Unlike traditional surface treatments, film-forming sprays provide uniform drug distribution, better bioavailability, effective CO₂ retention by sealing pores, and antibacterial effects. The spray includes a polymer to encapsulate phytoconstituents and form the film. The resulting film is highly water-resistant, glossy, transparent, and dries within two minutes. SEM analysis showed a fine, uniform morphology, while zeta analysis revealed a negative potential of −0.342 mV and conductivity of 0.390 mS/cm, indicating stable dispersion. The spray’s effectiveness was tested on 640 chicken eggs stored at varying temperatures. Eggs treated and kept at 2–8 °C showed the best results, with smaller air cells, higher specific gravity, and superior quality indicators such as pH, albumen weight, albumen height and index, Haugh unit, yolk weight, and yolk index. Additionally, the spray significantly reduced microbial load, including total plate count and E. coli. Eggs stored at 28 °C remained safe for 24–30 days, while those at 2–8 °C lasted over 42 days. This innovative film-forming spray offers a promising approach for preserving internal and external egg quality during storage. Full article

(This article belongs to the Section Polymer Applications)

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22 pages, 5497 KiB

Open AccessArticle

Adsorption Capacity, Reaction Kinetics and Thermodynamic Studies on Ni(II) Removal with GO@Fe₃O₄@Pluronic-F68 Nanocomposite

by Ali Çiçekçi, Fatih Sevim, Melike Sevim and Erbil Kavcı

Polymers 2025, 17(15), 2141; https://doi.org/10.3390/polym17152141 - 5 Aug 2025

Viewed by 245

Abstract

In recent years, industrial wastewater discharge containing heavy metals has increased significantly and has adversely affected both human health and the aquatic ecosystem. The increasing demand for metals in industry has prompted researchers to focus on developing effective and economical methods for removal [...] Read more.

In recent years, industrial wastewater discharge containing heavy metals has increased significantly and has adversely affected both human health and the aquatic ecosystem. The increasing demand for metals in industry has prompted researchers to focus on developing effective and economical methods for removal of these metals. In this study, the removal of Ni(II) from wastewater using the Graphene oxide@Fe₃O₄@Pluronic-F68 (GO@Fe₃O₄@Pluronic-F68) nano composite as an adsorbent was investigated. The nanocomposite was characterised using a series of analytical methods, including Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) analysis. The effects of contact time, pH, adsorbent amount, and temperature parameters on adsorption were investigated. Various adsorption isotherm models were applied to interpret the equilibrium data in aqueous solutions; the compatibility of the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models with experimental data was examined. For a kinetic model consistent with experimental data, pseudo-first-order, pseudo-second-order, Elovich, and intra-particle diffusion models were examined. The maximum adsorption capacity was calculated as 151.5 mg·g⁻¹ in the Langmuir isotherm model. The most suitable isotherm and kinetic models were the Freundlich and pseudo-second-order kinetic models, respectively. These results demonstrate the potential of the GO@Fe₃O₄@Pluronic-F68 nanocomposite as an adsorbent offering a sustainable solution for Ni(II) removal. Full article

(This article belongs to the Section Polymer Composites and Nanocomposites)

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26 pages, 5455 KiB

Open AccessArticle

Features of Thermal Stabilization of PVC Modified with Microstructured Titanium Phosphate

by Irina N. Vikhareva, Anton Abramian, Dragan Manojlović and Oleg Bol’shakov

Polymers 2025, 17(15), 2140; https://doi.org/10.3390/polym17152140 - 5 Aug 2025

Viewed by 268

Abstract

Poly(vinyl chloride) (PVC) undergoes thermal degradation during processing and operation, which necessitates the use of effective thermal stabilizers. The purpose of this work is to comprehensively evaluate the potential of new hierarchically structured titanium phosphates (TiP) with controlled morphology as thermal stabilizers of [...] Read more.

Poly(vinyl chloride) (PVC) undergoes thermal degradation during processing and operation, which necessitates the use of effective thermal stabilizers. The purpose of this work is to comprehensively evaluate the potential of new hierarchically structured titanium phosphates (TiP) with controlled morphology as thermal stabilizers of plasticized PVC, focusing on the effect of morphology and Ti/P ratio on their stabilizing efficiency. The thermal stability of the compositions was studied by thermogravimetric analysis (TGA) in both inert (Ar) and oxidizing (air) atmospheres. The effect of TiP concentration and its synergy with industrial stabilizers was analyzed. An assessment of the key degradation parameters is given: the temperature of degradation onset, the rate of decomposition, exothermic effects, and the carbon residue yield. In an inert environment, TiPMSI/TiPMSII microspheres demonstrated an optimal balance by increasing the temperature of degradation onset and the residual yield while suppressing the rate of decomposition. In an oxidizing environment, TiPR rods and TiPMSII microspheres provided maximum stability, enhancing resistance to degradation onset and reducing the degradation rate by 10–15%. Key factors of effectiveness include ordered morphology (spheres, rods); the Ti-deficient Ti/P ratio (~0.86), which enhances HCl binding; and crystallinity. The stabilization mechanism of titanium phosphates is attributed to their high affinity for hydrogen chloride (HCl), which catalyzes PVC chain scission, a catalyst for the destruction of the PVC chain. The unique microstructure of titanium phosphate provides a high specific surface area and, as a result, greater activity in the HCl neutralization reaction. The formation of a sol–phosphate framework creates a barrier to heat and oxygen. An additional contribution comes from the inhibition of oxidative processes and the possible interaction with unstable chlorallyl groups in PVC macromolecules. Thus, hierarchically structured titanium phosphates have shown high potential as multifunctional PVC thermostabilizers for modern polymer materials. Potential applications include the development of environmentally friendly PVC formulations with partial or complete replacement of toxic stabilizers, the optimization of thermal stabilization for products used in aggressive environments, and the use of hierarchical TiP structures in flame-resistant and halogen-free PVC-based compositions. Full article

(This article belongs to the Section Polymer Processing and Engineering)

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20 pages, 4676 KiB

Open AccessArticle

Multifunctional, Biocompatible Hybrid Surface Coatings Combining Antibacterial, Hydrophobic and Fluorescent Applications

by Gökçe Asan and Osman Arslan

Polymers 2025, 17(15), 2139; https://doi.org/10.3390/polym17152139 - 5 Aug 2025

Viewed by 443

Abstract

The hybrid inorganic–organic material concept plays a bold role in multifunctional materials, combining different features on one platform. Once varying properties coexist without cancelling each other on one matrix, a new type of supermaterial can be formed. This concept showed that silver nanoparticles [...] Read more.

The hybrid inorganic–organic material concept plays a bold role in multifunctional materials, combining different features on one platform. Once varying properties coexist without cancelling each other on one matrix, a new type of supermaterial can be formed. This concept showed that silver nanoparticles can be embedded together with inorganic and organic surface coatings and silicon quantum dots for symbiotic antibacterial character and UV-excited visible light fluorescent features. Additionally, fluorosilane material can be coupled with this prepolymeric structure to add the hydrophobic feature, showing water contact angles around 120°, providing self-cleaning features. Optical properties of the components and the final material were investigated by UV-Vis spectroscopy and PL analysis. Atomic investigations and structural variations were detected by XPS, SEM, and EDX atomic mapping methods, correcting the atomic entities inside the coating. FT-IR tracked surface features, and statistical analysis of the quantum dots and nanoparticles was conducted. Multifunctional final materials showed antibacterial properties against E. coli and S. aureus, exhibiting self-cleaning features with high surface contact angles and visible light fluorescence due to the silicon quantum dot incorporation into the sol-gel-produced nanocomposite hybrid structure. Full article

(This article belongs to the Special Issue Polymer Coatings for High-Performance Applications)

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16 pages, 10388 KiB

Open AccessArticle

Highly-Oriented Polylactic Acid Fiber Reinforced Polycaprolactone Composite Produced by Infused Fiber Mat Process for 3D Printed Tissue Engineering Technology

by Zhipeng Deng, Chen Rao, Simin Han, Qungui Wei, Yichen Liang, Jialong Liu and Dazhi Jiang

Polymers 2025, 17(15), 2138; https://doi.org/10.3390/polym17152138 - 5 Aug 2025

Viewed by 395

Abstract

Three-dimensional printed polycaprolactone (PCL) tissue engineering scaffolds have drawn increasing interest from the medical industry due to their excellent biocompatibility and biodegradability, yet PCL’s poor mechanical performance has limited their applications. This study introduces a biocompatible and biodegradable polylactic acid (PLA) fiber reinforced [...] Read more.

Three-dimensional printed polycaprolactone (PCL) tissue engineering scaffolds have drawn increasing interest from the medical industry due to their excellent biocompatibility and biodegradability, yet PCL’s poor mechanical performance has limited their applications. This study introduces a biocompatible and biodegradable polylactic acid (PLA) fiber reinforced PCL (PLA/PCL) composite as the filament for 3D printed scaffolds to significantly enhance their mechanical performance: Special-made PLA short fiber mat was infused with PCL matrix and rolled into PLA/PCL filaments through a “Vacuum Assisted Resin Infusion” (VARI) process. The investigation revealed that the PLA fibers are highly oriented along the printing direction when using this filament for 3D printing due to the unique microstructure formed during the VARI process. At the same PLA fiber content, the percentage increase in Young’s modulus of the 3D printed strands using the filaments produced by the VARI process is 127.6% higher than the 3D printed strands using the filaments produced by the conventional melt blending process. The 3D printed tissue engineering scaffolds using the PLA/PCL composite filament with 11 wt% PLA fiber content also achieved an exceptional 84.2% and 143.3% increase in peak load and stiffness compared to the neat PCL counterpart. Full article

(This article belongs to the Special Issue Additive Manufacturing of Polymer-Based Materials and Lightweight Structures)

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21 pages, 6166 KiB

Open AccessArticle

Effect of Thermal Cycles on the Compressive Properties of 3D-Printed Polymeric Lattice-Reinforced Cement-Based Materials

by Can Tang, Yujie Zhou, Jing Qiao, Humaira Kanwal, Guoqian Song and Wenfeng Hao

Polymers 2025, 17(15), 2137; https://doi.org/10.3390/polym17152137 - 4 Aug 2025

Viewed by 404

Abstract

Existing studies have shown that placing 3D-printed lattices in cement matrices can effectively improve the ductility of cement-based composites. However, the influence of thermal fatigue effect on the mechanical properties of 3D-printed lattice-reinforced cement-based composites during service remains to be studied. In this [...] Read more.

Existing studies have shown that placing 3D-printed lattices in cement matrices can effectively improve the ductility of cement-based composites. However, the influence of thermal fatigue effect on the mechanical properties of 3D-printed lattice-reinforced cement-based composites during service remains to be studied. In this paper, cement-based materials without lattices were used as the control group, and the uniaxial compressive mechanical properties of 3D-printed lattice-reinforced cement-based composites after thermal fatigue treatment under a temperature difference of 60 °C were tested. The number of thermal fatigue cycles was set to 45, 90, and 145 times, respectively. During the test, two non-destructive testing technologies, AE and DIC, were used to analyze the strength degradation and deformation law of 3D-printed lattice-reinforced cement-based composites with the increase in cycles. AE adopted the threshold triggering mode, and the channel threshold was 100 mv. The experiment showed that the compressive strength of the control group after 45, 90, and 145 thermal cycles decreased to 72.47% and 49.44% of that of the specimen after 45 thermal cycles, respectively. The strength of RO lattices decreased to 91.07% and 82.14% of that of the specimen after 45 thermal cycles, respectively, while the strength of SO lattices decreased to 83.27% and 77.96% of that of the specimen after 45 thermal cycles, respectively. The compressive strengths of the two types of lattices were higher than that of the control group after three cycles, indicating that 3D-printed lattices can effectively mitigate the influence of environmental thermal fatigue on the mechanical properties of cement-based materials. Full article

(This article belongs to the Special Issue Polymeric Materials and Their Application in 3D Printing, 2nd Edition)

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21 pages, 2608 KiB

Open AccessReview

Recent Progress on the Research of 3D Printing in Aqueous Zinc-Ion Batteries

by Yating Liu, Haokai Ding, Honglin Chen, Haoxuan Gao, Jixin Yu, Funian Mo and Ning Wang

Polymers 2025, 17(15), 2136; https://doi.org/10.3390/polym17152136 - 4 Aug 2025

Viewed by 471

Abstract

The global transition towards a low-carbon energy system urgently demands efficient and safe energy storage solutions. Aqueous zinc-ion batteries (AZIBs) are considered a promising alternative to lithium-ion batteries due to their inherent safety and environmental friendliness. However, conventional manufacturing methods are costly and [...] Read more.

The global transition towards a low-carbon energy system urgently demands efficient and safe energy storage solutions. Aqueous zinc-ion batteries (AZIBs) are considered a promising alternative to lithium-ion batteries due to their inherent safety and environmental friendliness. However, conventional manufacturing methods are costly and labor-intensive, hindering their large-scale production. Recent advances in 3D printing technology offer innovative pathways to address these challenges. By combining design flexibility with material optimization, 3D printing holds the potential to enhance battery performance and enable customized structures. This review systematically examines the application of 3D printing technology in fabricating key AZIB components, including electrodes, electrolytes, and integrated battery designs. We critically compare the advantages and disadvantages of different 3D printing techniques for these components, discuss the potential and mechanisms by which 3D-printed structures enhance ion transport and electrochemical stability, highlight critical existing scientific questions and research gaps, and explore potential strategies for optimizing the manufacturing process. Full article

(This article belongs to the Special Issue Polymeric Materials for Next-Generation Energy Storage)

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20 pages, 3145 KiB

Open AccessArticle

Determination of Dynamic Elastic Properties of 3D-Printed Nylon 12CF Using Impulse Excitation of Vibration

by Pedro F. Garcia, Armando Ramalho, Joel C. Vasco, Rui B. Ruben and Carlos Capela

Polymers 2025, 17(15), 2135; https://doi.org/10.3390/polym17152135 - 4 Aug 2025

Viewed by 341

Abstract

Material Extrusion (MEX) process is increasingly used to fabricate components for structural applications, driven by the availability of advanced materials and greater industrial adoption. In these contexts, understanding the mechanical performance of printed parts is crucial. However, conventional methods for assessing anisotropic elastic [...] Read more.

Material Extrusion (MEX) process is increasingly used to fabricate components for structural applications, driven by the availability of advanced materials and greater industrial adoption. In these contexts, understanding the mechanical performance of printed parts is crucial. However, conventional methods for assessing anisotropic elastic behavior often rely on expensive equipment and time-consuming procedures. The aim of this study is to evaluate the applicability of the impulse excitation of vibration (IEV) in characterizing the dynamic mechanical properties of a 3D-printed composite material. Tensile tests were also performed to compare quasi-static properties with the dynamic ones obtained through IEV. The tested material, Nylon 12CF, contains 35% short carbon fibers by weight and is commercially available from Stratasys. It is used in the fused deposition modeling (FDM) process, a Material Extrusion technology, and exhibits anisotropic mechanical properties. This is further reinforced by the filament deposition process, which affects the mechanical response of printed parts. Young’s modulus obtained in the direction perpendicular to the deposition plane (E₃₃), obtained via IEV, was 14.77% higher than the value in the technical datasheet. Comparing methods, the Young’s modulus obtained in the deposition plane, in an inclined direction of 45 degrees in relation to the deposition direction (E₄₅), showed a 22.95% difference between IEV and tensile tests, while Poisson’s ratio in the deposition plane (v₁₂) differed by 6.78%. This data is critical for designing parts subject to demanding service conditions, and the results obtained (orthotropic elastic properties) can be used in finite element simulation software. Ultimately, this work reinforces the potential of the IEV method as an accessible and consistent alternative for characterizing the anisotropic properties of components produced through additive manufacturing (AM). Full article

(This article belongs to the Special Issue Mechanical Characterization of Polymer Composites)

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24 pages, 5000 KiB

Open AccessArticle

A Study of Methylene Blue Adsorption by a Synergistic Adsorbent Algae (Nostoc sphaericum)/Activated Clay

by Yakov Felipe Carhuarupay-Molleda, Noemí Melisa Ccasa Barboza, Sofía Pastor-Mina, Carlos Eduardo Dueñas Valcarcel, Ybar G. Palomino-Malpartida, Rolando Licapa Redolfo, Antonieta Mojo-Quisani, Miriam Calla-Florez, Rolando F. Aguilar-Salazar, Yovana Flores-Ccorisapra, Arturo Rojas Benites, Edward Arostegui León, David Choque-Quispe and Frida E. Fuentes Bernedo

Polymers 2025, 17(15), 2134; https://doi.org/10.3390/polym17152134 - 4 Aug 2025

Viewed by 422

Abstract

Dye residues from the textile industry constitute a critical wastewater problem. This study aimed to evaluate the removal capacity of methylene blue (MB) in aqueous media, using an adsorbent formulated from activated and sonicated nanoclay (NC) and microatomized Nostoc sphaericum (ANS). NC was [...] Read more.

Dye residues from the textile industry constitute a critical wastewater problem. This study aimed to evaluate the removal capacity of methylene blue (MB) in aqueous media, using an adsorbent formulated from activated and sonicated nanoclay (NC) and microatomized Nostoc sphaericum (ANS). NC was obtained by acid treatment, followed by activation with 1 M NaCl and sonication, while ANS was obtained by microatomization in an aqueous medium. NC/ANS was mixed in a 4:1 weight ratio. The NC/ANS synergistic adsorbent was characterized by the point of zero charge (PZC), zeta potential (ζ), particle size, FTIR spectroscopy, and scanning electron microscopy (SEM). NC/ANS exhibited good colloidal stability, as determined by pH_PZC, particle size in the nanometer range, and heterogeneous morphology with functional groups (hydroxyl, carboxyl, and amide), removing between 72.59 and 97.98% from an initial concentration of 10 ppm of MB, for doses of 20 to 30 mg/L of NC/ANS and pH of 5 to 8. Optimal adsorption conditions are achieved at pH 6.8 and 32.9 mg/L of adsorbent NC/ANS. It was observed that the pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models best described the adsorption kinetics, indicating a predominance of the physisorption process, with adsorption capacity around 20 mg/g. Isotherm models and thermodynamic parameters of adsorption, ΔS, ΔH, and ΔG, revealed that the adsorption process is spontaneous, favorable, thermodynamically stable, and occurs at the monolayer level, with a regeneration capacity of 90.35 to 37.54% at the fifth cycle. The application of physical activation methods, such as sonication of the clay and microatomization of the algae, allows proposing a novel and alternative synergistic material from organic and inorganic sources that is environmentally friendly and promotes sustainability, with a high capacity to remove cationic dyes in wastewater. Full article

(This article belongs to the Special Issue Eco-Friendly Polymers as Future Wastewater Decontamination Alternative)

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Polymers, Volume 17, Issue 15 (August-1 2025) – 165 articles

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