Polymers

21 pages, 9141 KiB

Open AccessArticle

Isolation, Identification and Screening of Plastic-Degrading Microorganisms: Qualitative and Structural Effects on Poly(Butylene Succinate) (PBS) Films

by Cristina América Morando-Grijalva, Ana Ramos-Díaz, Angel H. Cabrera-Ramirez, Juan Carlos Cuevas-Bernardino, Soledad Cecilia Pech-Cohuo, Angela Francisca Kú-González, Julia Cano-Sosa, Iván Emanuel Herrera-Pool, Sergio Valdivia-Rivera, Teresa Ayora-Talavera and Neith Pacheco

Polymers 2025, 17(8), 1128; https://doi.org/10.3390/polym17081128 - 21 Apr 2025

Abstract

(1) Background: Plastic contamination is on the rise, despite ongoing research focused on alternatives such as bioplastics. However, most bioplastics require specific conditions to biodegrade. A promising alternative involves using microorganisms isolated from landfill soils that have demonstrated the ability to degrade plastic [...] Read more.

(1) Background: Plastic contamination is on the rise, despite ongoing research focused on alternatives such as bioplastics. However, most bioplastics require specific conditions to biodegrade. A promising alternative involves using microorganisms isolated from landfill soils that have demonstrated the ability to degrade plastic materials. (2) Methods: Soil samples were collected, and bacteria were isolated, characterized, and molecularly identified. Their degradative capacity was evaluated using the zone of clearing method, while their qualitative and structural degradative activity was assessed in a liquid medium on poly(butylene succinate) (PBS) films prepared by the cast method. (3) Results: Three strains—Bacillus cereus CHU4R, Acinetobacter baumannii YUCAN, and Pseudomonas otitidis YUC44—were selected. These strains exhibited the ability to cause severe damage to the microscopic surface of the films, attack the ester bonds within the PBS structure, and degrade lower-weight PBS molecules during the process. (4) Conclusions: this study represents the first report of strains isolated in Yucatán with plastic degradation activity. The microorganisms demonstrated the capacity to degrade PBS films by causing surface and structural damage at the molecular level. These findings suggest that the strains could be applied as an alternative in plastic biodegradation. Full article

(This article belongs to the Special Issue Embracing the Circular Economy for a Promising Future in Sustainable Polymer Production)

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18 pages, 5552 KiB

Open AccessArticle

Use of a Sorption Column with Polyurethane/Graphene Core Combined with an Electroflotation Reactor for Oily Wastewater Treatment

by Tiago Mari, Matheus V. G. Zimmermann, Bruna Rossi Fenner, Francisco Maciel Monticeli, Heitor Luiz Ornaghi Júnior, Camila Baldasso and Ademir J. Zattera

Polymers 2025, 17(8), 1127; https://doi.org/10.3390/polym17081127 - 21 Apr 2025

Abstract

Discharging oil-contaminated wastewater into the environment without adequate treatment can have a negative impact on water resources, public water and wastewater treatment systems, and even human health. In this sense, it is essential to develop compact, easily automated, low-cost, and highly efficient unitary [...] Read more.

Discharging oil-contaminated wastewater into the environment without adequate treatment can have a negative impact on water resources, public water and wastewater treatment systems, and even human health. In this sense, it is essential to develop compact, easily automated, low-cost, and highly efficient unitary treatment processes in order to comply with legal requirements regarding effluent emission standards for water bodies. Therefore, the present study consisted of the development of two treatment processes aimed at the separation of oil emulsions stabilised by anionic surfactants: a sorption column using polyurethane/graphene foam composites as sorbent material and a continuous flow AC electroflotation reactor. Initially, composites with 0.5% and 1% w/w graphene (based on polyol mass) were developed using a dispersing agent (1-methyl-2-pyrrolidone). The foams were characterised in terms of morphology and mechanical and sorption properties. In the fixed bed column, the foams retained up to 77.15% of the emulsified oil and 52.36% of the anionic surfactants. In the continuous flow electroflotation reactor, emulsified oil removal efficiencies above 90% were achieved at all electrical currents tested, and up to 88.6% of anionic surfactants were removed at an electrical current of 150 A. Given the advantages and disadvantages of the two oily effluent treatment processes, their combined use in the same system proved promising. Full article

(This article belongs to the Section Polymer Applications)

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15 pages, 8506 KiB

Open AccessArticle

Mitigation of Sink Voids in Thick-Walled Thermoplastic Components via Integrated Taguchi DOE and CAE Simulations

by Feng Wang, Wenbo Luo, Jiling Bu, Bo Zou and Xingwu Ding

Polymers 2025, 17(8), 1126; https://doi.org/10.3390/polym17081126 - 21 Apr 2025

Abstract

A gauge plate is a typical thick-walled injection-molded component featuring a complex construction used in high-speed railways, and it is prone to sink voids during the injection process. It is difficult to obtain a void-free injection molded part due to uneven cooling-induced localized [...] Read more.

A gauge plate is a typical thick-walled injection-molded component featuring a complex construction used in high-speed railways, and it is prone to sink voids during the injection process. It is difficult to obtain a void-free injection molded part due to uneven cooling-induced localized thermal gradients, crystallization shrinkage of semicrystalline thermoplastics, fiber orientation-induced anisotropic shrinkage, injection parameter-dependent fountain flow, and inconsistent core compensation. This work employed design of experiment (DOE) and computer-aided engineering (CAE) simulations to analyze the influence of injection parameters on the volumetric shrinkage of the gauge plate and to identify the optimal injection process. A Taguchi orthogonal array L9 was applied, in which four injection molding process parameters were varied at three different levels. The fundamental causes of sink void defects in the gauge plate were then examined via MoldFlow analysis on the basis of the optimized injection parameters. The MoldFlow study indicates a high probability of the presence of sink void defects in the injection-molded gauge plate. To minimize sink void defects, a structural optimization design of the gauge plate was implemented to achieve a more uniform wall thickness, and the advantages of this optimization were demonstrated via comparative analysis. The small batch production of the injection-molded gauge plates demonstrates that the optimized gauge plate shows no sink voids, ensuring consistent quality that adheres to the engineering process and technical specifications. Full article

(This article belongs to the Special Issue Advanced Polymer Composite Materials: Processing, Modeling, Properties and Applications III)

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30 pages, 6502 KiB

Open AccessArticle

Sustainable Medical Materials: AI-Driven Assessment for Mechanical Performance of UVC-Treated Date Palm Epoxy Composites

by Mohamed A. Aboamer, Abdulrahman Hakami, Meshari Algethami, Ibrahim M. Alarifi, Tarek M. A. A. El-Bagory, Ahmad Alassaf, Bakheet A. Alresheedi, Ahmad K. AlOmari, Abdulaziz Abdullah Almazrua and Nader A. Rahman Mohamed

Polymers 2025, 17(8), 1125; https://doi.org/10.3390/polym17081125 - 21 Apr 2025

Abstract

This study investigates the AI-assisted analyses of radiation disinfection effects on the mechanical properties of recycled date kernel powder–epoxy composites for medical applications, utilizing Euclidean distances and the k-nearest neighbor (KNN) algorithm. Tensile and compression tests were conducted on twenty specimens following ASTM [...] Read more.

This study investigates the AI-assisted analyses of radiation disinfection effects on the mechanical properties of recycled date kernel powder–epoxy composites for medical applications, utilizing Euclidean distances and the k-nearest neighbor (KNN) algorithm. Tensile and compression tests were conducted on twenty specimens following ASTM standards, with the data analyzed using a t-test to evaluate the impact of the UVC disinfection process on the material’s mechanical properties. The application of AI through the KNN algorithm successfully identified the three most representative curves out of five for both tensile and compression tests. This targeted curve selection minimized variability and focused on the most relevant data, enhancing the reliability of the analysis. Following the application of UVC and AI, tensile tests showed a 20–30% increase in ultimate stress. Similarly, compression tests revealed a 25% increase in transition stress, an 18–22% improvement in ultimate stress, and approximately a 12% rise in fracture stress. This research underscores the potential of combining AI, sustainable materials, and UVC technology to develop advanced composites for medical applications. The proposed methodology offers a robust framework for evaluating material performance while promoting the creation of eco-friendly, high-performance materials that meet the stringent standards of medical use. Full article

(This article belongs to the Special Issue Advanced Fiber-Reinforced Polymer Composites: Design, Manufacturing, Characterization, and Application)

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23 pages, 4255 KiB

Open AccessReview

Trends and Future Projections in Ultrasonic Welding Research for Hybrid Materials

by Jedaías J. Silva, Rafael G. C. da Silva, Carolina L. Morelli, Edwar A. T. López and Tiago F. A. Santos

Polymers 2025, 17(8), 1124; https://doi.org/10.3390/polym17081124 - 21 Apr 2025

Abstract

Ultrasonic welding has gained interest from various researchers and industries worldwide, particularly for joining dissimilar materials in sectors such as aerospace, aeronautics, and electronics. This paper presents a comprehensive bibliometric review aimed at mapping the evolving landscape of ultrasonic welding research. Through the [...] Read more.

Ultrasonic welding has gained interest from various researchers and industries worldwide, particularly for joining dissimilar materials in sectors such as aerospace, aeronautics, and electronics. This paper presents a comprehensive bibliometric review aimed at mapping the evolving landscape of ultrasonic welding research. Through the systematic analysis of 1913 scientific documents, it identifies key advances, challenges, and future directions in the field. Furthermore, the bibliometric analysis sheds light on annual scientific production, prolific authors and institutions, scientific contribution per country, and methodological approaches. The global collaboration network comprises countries from all continents, with a prominent presence in Europe, Asia, and the Americas and less representation from African and Oceanian countries. China and the United States dominate the field in terms of scientific document production, international collaborations, and citations, with Germany also standing out for leading the number of citations in research related to hybrid metal/polymer joining. This review aims to serve as a valuable resource for researchers, practitioners, and policymakers interested in the advancements and future directions of ultrasonic welding for hybrid materials. Full article

(This article belongs to the Special Issue Polymer Joining Techniques: Innovations, Challenges, and Applications)

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16 pages, 4184 KiB

Open AccessArticle

Low Shrinkage Transparent UV-Cured 3D Printing Hard Silicone Resins

by Haibo Wu, Qili Shen, Zhu Liu, Xiantai Zhou, Yanxiong Fang, Hongping Xiang and Xiaoxuan Liu

Polymers 2025, 17(8), 1123; https://doi.org/10.3390/polym17081123 - 21 Apr 2025

Abstract

Acrylated silicone elastomers for UV-curing 3D printing have gathered considerable attention in biomedical applications due to their exceptional mechanical and thermal stability. However, traditional manufacturing methods for these resins often face challenges such as stringent conditions and self-polymerization. In this study, various acrylate [...] Read more.

Acrylated silicone elastomers for UV-curing 3D printing have gathered considerable attention in biomedical applications due to their exceptional mechanical and thermal stability. However, traditional manufacturing methods for these resins often face challenges such as stringent conditions and self-polymerization. In this study, various acrylate silicone resins (LMDT-AE) and silicone oils (PDMS-AE) were synthesized through ring-opening hydrolysis-polycondensation. The structures of LMDT-AE and PDMS-AE, with varying AE contents (molar ratio of organic groups to silicon atoms), were characterized using FTIR, ¹H NMR, ¹³C NMR, and GPC. Additionally, their physical properties, including viscosity, density, refractive index, and transparency, were thoroughly examined. The 3D-AE silicone resin composed of LMDT-AE-2.0 and PDMS-AE-20/1, in a mass ratio of 2:1, demonstrated superior mechanical properties, thermal stability, and curing shrinkage rate compared to other formulations. This curing silicone resin is capable of producing 3D physical entities with smooth surfaces and well-defined contours. It is shown that the successful preparation of transparent and high-strength UV-cured silicone resin based on free radical polymerization can provide a potential path for high-precision biological 3D printing. Full article

(This article belongs to the Special Issue Polymer Materials for Application in Additive Manufacturing)

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25 pages, 4391 KiB

Open AccessArticle

Synthesis, Characterization, and Self-Assembly Behavior of Block Copolymers of N-Vinyl Pyrrolidone with n-Alkyl Methacrylates

by Nikoletta Roka and Marinos Pitsikalis

Polymers 2025, 17(8), 1122; https://doi.org/10.3390/polym17081122 - 21 Apr 2025

Abstract

Novel amphiphilic block copolymers of N-vinyl pyrrolidone (NVP) and either n-hexyl methacrylate (HMA, PNVP-b-PHMA) or stearyl methacrylate (SMA, PNVP-b-PSMA) were prepared by RAFT polymerization techniques and the sequential addition of monomers starting from the polymerization of NVP and using [...] Read more.

Novel amphiphilic block copolymers of N-vinyl pyrrolidone (NVP) and either n-hexyl methacrylate (HMA, PNVP-b-PHMA) or stearyl methacrylate (SMA, PNVP-b-PSMA) were prepared by RAFT polymerization techniques and the sequential addition of monomers starting from the polymerization of NVP and using two different Chain Transfer Agents, CTAs. PNVP-b-PHMA are amorphous block copolymers containing constituent blocks with both high and low Tg values, whereas PNVP-b-PSMA are amorphous–semi-crystalline copolymers. Samples with different molecular weights and compositions were obtained. The copolymers were microphase-separated, but partial mixing was also observed. The presence of the amorphous PNVP block reduced the crystallinity of the PSMA blocks in the PNVP-b-PSMA copolymers. The thermal stability of the blocks was influenced by both constituents. The self-assembly behavior in THF, which is a selective solvent for polymethacrylate blocks, and in aqueous solutions, where PNVP was soluble, was examined. Unimolecular or low-aggregation-number micelles were obtained in THF for both types of samples. On the contrary, high-aggregation-number, spherical, and compact micelles were revealed in aqueous solutions. The increase in the steric hindrance of the side ester group of the polymethacrylate chain led to slightly lower degrees of association. The hydrophobic compound curcumin was efficiently encapsulated within the micellar core of the supramolecular structures in aqueous solutions. Micelles with higher aggregation numbers were more efficient in the encapsulation of curcumin. The results of this study were compared with those obtained from other block copolymers based on PNVP. Full article

(This article belongs to the Special Issue Block Copolymers: Self-Assembly and Applications, 2nd Edition)

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19 pages, 8390 KiB

Open AccessArticle

Research on the Tribological Behavior of Polyurethane Acrylate Coatings with Different Matrix Constituents as Well as Graphite and PTFE

by Weihua Cao, Xiao Yang, Zhenjie Song, Jia Geng, Changxin Liu, Ning Zhang and Xiaowen Qi

Polymers 2025, 17(8), 1121; https://doi.org/10.3390/polym17081121 - 21 Apr 2025

Abstract

With the aim of developing a wear-resistant ultraviolet (UV)-cured self-lubricating coating, this study investigated the impact of matrix components and lubricants on UV-cured interpenetrating polymer network-polyurethane acrylate (IPN-PUA) self-lubricating coatings. Four coatings with different monomer combinations were prepared, using isophorone diisocyanate (IPDI) or [...] Read more.

With the aim of developing a wear-resistant ultraviolet (UV)-cured self-lubricating coating, this study investigated the impact of matrix components and lubricants on UV-cured interpenetrating polymer network-polyurethane acrylate (IPN-PUA) self-lubricating coatings. Four coatings with different monomer combinations were prepared, using isophorone diisocyanate (IPDI) or tolylene-2,4-diisocyanate (TDI) in combination with hydroxypropyl acrylate (HPA) or 2-hydroxyethyl acrylate (HEA). These coatings were denoted as IPDI-HPA, IPDI-HEA, TDI-HPA, and TDI-HEA, respectively. The surface morphologies, compositions, friction and wear properties, as well as the comprehensive performances were investigated. The results indicated that IPDI-HPA had the lowest surface roughness and that TDI-HEA had the smallest wear rate, while TDI-HPA showed the best overall performance (roughness of 1.485 μm, coefficient of friction (COF) of 0.746, and wear rate of 10.64 × 10⁻¹⁴ m³/N·m). With TDI-HPA as the matrix, graphite and polytetrafluoroethylene (PTFE) particles of different sizes were added as lubricants. The T-P-25F (TDI-HPA coating with 25 μm sized PTFE) coating had self-lubricating capabilities, as was manifested by a friction coefficient of 0.395, which was 47% lower than that of the pure TDI-HPA coating, and it simultaneously showed outstanding wear-resistance performance. The wear rate of the T-P-25F coating was 3.97 × 10⁻¹⁴ m³/N·m, 62.7% lower than that of the pure TDI-HPA coating. This research provides valuable guidance for optimizing the performance of such coatings and yields a self-lubricating coating with excellent wear resistance. Full article

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

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20 pages, 5439 KiB

Open AccessArticle

Polyvinylidene Fluoride (PVDF) and Nanoclay Composites’ Mixed-Matrix Membranes: Exploring Structure, Properties, and Performance Relationships

by Rund Abu-Zurayk, Nour Alnairat, Haneen Waleed, Mohammed Q. Al-Khaial, Aya Khalaf, Ayat Bozeya, Duaa Abu-Dalo, Sojoud Al-Yousef and Razan Afaneh

Polymers 2025, 17(8), 1120; https://doi.org/10.3390/polym17081120 - 20 Apr 2025

Abstract

Polyvinylidene fluoride (PVDF) membranes have become a favored choice for membrane filtration because of their outstanding mechanical characteristics, chemical resistance, thermal stability, and ease of handling. Nevertheless, the hydrophobic nature of PVDF membranes can result in fouling, which diminishes their efficiency over time. [...] Read more.

Polyvinylidene fluoride (PVDF) membranes have become a favored choice for membrane filtration because of their outstanding mechanical characteristics, chemical resistance, thermal stability, and ease of handling. Nevertheless, the hydrophobic nature of PVDF membranes can result in fouling, which diminishes their efficiency over time. This study explores the impact of ZnO-Nanoclay on the properties and performance of mixed matrix membranes made from polyvinylidene fluoride (PVDF) at different loading percentages (0, 1, and 3 wt%). The ZnO-Nanoclay nanoparticles were synthesized using environmentally friendly methods, characterized, and blended into PVDF matrices via a solution-casting technique, resulting in a series of membranes. The synthesized nanoparticles were analyzed using Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). The resulting mixed-matrix membranes underwent comprehensive analyses to assess their structure and surface properties, employing SEM, XRD, Atomic Force Microscopy (AFM), and contact-angle measurements. Furthermore, tensile, antibacterial, and barrier properties were evaluated. Integrating ZnO-Nanoclay into PVDF membranes greatly improves antifouling properties, achieving inhibition rates of 99.92% at a clay-loading percentage of 3 wt% and increasing water-flux rates by 16% compared to pure PVDF membranes at 1 wt%. In addition, ZnO-Nanoclay nanoparticles significantly boost the mechanical properties of PVDF membranes, enhancing maximum strength by 500% at 3 wt% loading. This study examines the interplay between the structure, properties, and performance of mixed-matrix membranes by comparing different PVDF membranes that were mixed with different nanoclay composites, providing significant insights into improving these membranes through the incorporation of nanoclay composites to enhance their overall properties and effectiveness. Full article

(This article belongs to the Section Polymer Applications)

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23 pages, 6989 KiB

Open AccessArticle

Study on the Uniaxial Compression Constitutive Relationship of Wood Reinforced with Fiber-Reinforced Polymer

by Hao Chen, Zihui Zhang, Zhihui Wang and Yongcheng Ji

Polymers 2025, 17(8), 1119; https://doi.org/10.3390/polym17081119 - 20 Apr 2025

Abstract

Fiber-reinforced polymer (FRP) composites demonstrate significant advantages in the reinforcement of timber structures, with basalt fiber-reinforced polymer (BFRP) and carbon fiber-reinforced polymer (CFRP) exhibiting distinct characteristics. This study systematically compares the mechanical performance differences between BFRP- and CFRP-reinforced Northeast larch timber columns. Uniaxial [...] Read more.

Fiber-reinforced polymer (FRP) composites demonstrate significant advantages in the reinforcement of timber structures, with basalt fiber-reinforced polymer (BFRP) and carbon fiber-reinforced polymer (CFRP) exhibiting distinct characteristics. This study systematically compares the mechanical performance differences between BFRP- and CFRP-reinforced Northeast larch timber columns. Uniaxial compression tests focused on the mechanical responses under different reinforcement conditions along the grain direction. The results indicate that BFRP-reinforced specimens exhibit superior cost-effectiveness, enhanced ductility, and improved damage tolerance, whereas CFRP-reinforced specimens demonstrate higher stiffness and ultimate load-bearing capacity. A damage constitutive model, developed based on Poisson distribution theory, accurately describes the damage evolution process of fully FRP-reinforced Northeast larch timber columns. Numerical simulations show excellent agreement with experimental results. The study provides critical guidance for FRP material selection and reinforcement strategies in timber structure engineering: BFRP is more suitable for general applications prioritizing cost efficiency and ductility, while CFRP is better suited for special structures requiring higher load-bearing capacity. Finite element models of CFRP- and BFRP-reinforced timber specimens under axial compression were established using ABAQUS 2020 software, with simulation results closely matching experimental data. The proposed constitutive model and finite element analysis method offer a reliable tool for predicting the mechanical behavior of FRP-wood composite structures. Full article

(This article belongs to the Special Issue Polymers in Civil Engineering)

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28 pages, 10578 KiB

Open AccessArticle

Efficient Production and Experimental Analysis of Bio-Based PLA-CA Composite Membranes via Electrospinning for Enhanced Mechanical Performance and Thermal Stability

by Irfan Farooq and Abdulhamid Al-Abduljabbar

Polymers 2025, 17(8), 1118; https://doi.org/10.3390/polym17081118 - 20 Apr 2025

Abstract

Environmentally friendly biopolymer nanofibrous composite membranes with enhanced mechanical properties and thermal stability were fabricated via electrospinning with different compositions of polylactic acid (PLA) and cellulose acetate (CA). Firstly, PLA and CA composite membranes were prepared and optimized. Then, the optimized membranes were [...] Read more.

Environmentally friendly biopolymer nanofibrous composite membranes with enhanced mechanical properties and thermal stability were fabricated via electrospinning with different compositions of polylactic acid (PLA) and cellulose acetate (CA). Firstly, PLA and CA composite membranes were prepared and optimized. Then, the optimized membranes were annealed at temperatures ranging from 80 °C to 140 °C, for annealing times between 30 and 90 min. The developed membranes were characterized by FE-SEM, XRD, FR-IT, TGA, DSC, tensile testing, water contact angle, and resistance to hydrostatic pressure. PLA 95-CA 5 was the optimum composite, with a tensile strength 9.3 MPa, an average fiber diameter of 432 nm, a water contact angle of 135.7°, and resistance to a hydrostatic pressure of 16.5 KPa. Annealing resulted in further improvements in different properties. The annealed membranes had thermally stable microporous structures, without shrinkage or deterioration in nanofiber structure, even at an annealing time of 90 min and an annealing temperature of 140 °C. By increasing either the annealing time or temperature, the crystallinity and rigidity of the nanofiber composite membranes were increased. The annealed membrane demonstrated a tensile strength of 12.3 MPa, a water contact angle of 139.2°, and resistance to a hydrostatic pressure of 36 KPa. Electrospinning of PLA-CA composite membranes with enhanced mechanical properties and thermal stability will pave the way for employing PLA-based membranes in various applications. Full article

(This article belongs to the Topic Advanced Polymeric Composites: Processing, Characterization and Mechanical Behavior)

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31 pages, 4447 KiB

Open AccessReview

Starch Hydrogels for Slow and Controlled-Release Fertilizers: A Review

by Andrés Felipe Chamorro, Manuel Palencia and Enrique Miguel Combatt

Polymers 2025, 17(8), 1117; https://doi.org/10.3390/polym17081117 - 20 Apr 2025

Abstract

Fertilizers are widely used to increase agricultural productivity and ensure food security. However, their excessive use negatively impacts the environment, as a large portion is lost through leaching, degradation, and evaporation. Starch-based hydrogels (SHs) offer a promising alternative to mitigate these environmental effects [...] Read more.

Fertilizers are widely used to increase agricultural productivity and ensure food security. However, their excessive use negatively impacts the environment, as a large portion is lost through leaching, degradation, and evaporation. Starch-based hydrogels (SHs) offer a promising alternative to mitigate these environmental effects by enabling the controlled release of nutrients. SHs are biodegradable, non-toxic, and biocompatible, making them attractive for agricultural applications such as soil remediation and fertilizer delivery. These materials consist of crosslinked, three-dimensional networks with high water absorption capacity. Their effectiveness in nutrient delivery depends on the synthesis method, nutrient source, and environmental conditions. While the literature on SHs is growing, most studies focus on laboratory-scale production, which limits their broader application in agriculture. This review aims to consolidate current knowledge on SHs and identify research gaps to guide the development of more efficient and environmentally friendly SH-based fertilizers. It provides an overview of SH formation methods, including graft copolymerization, chemical crosslinking, and physical interactions. Additionally, the review highlights SH applications in controlled fertilizer release, discussing encapsulation capacity, large-scale production techniques, and nutrient delivery in aqueous media, soils, seeds, and plants. Full article

(This article belongs to the Special Issue Functional Polymeric Materials for Engineering and Environmental Applications)

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23 pages, 7536 KiB

Open AccessArticle

Development of Sustainable Polymer Composites Containing Waste Glass and Natural Fibers for Strengthening Purposes

by Cihan Karademir, Hasan Murat Tanarslan, Çağlar Yalçınkaya, Mustafa Furkan Güler, Hasan Ateş, Kutlay Sever, Yasemin Seki and Metehan Atagür

Polymers 2025, 17(8), 1116; https://doi.org/10.3390/polym17081116 - 20 Apr 2025

Abstract

This study investigates the development of sustainable polymer composites for structural strengthening by incorporating waste glass fibers and natural fibers (flax and hemp) into an epoxy matrix, in response to the growing environmental concerns. Mechanical, thermal, and durability-related properties were evaluated through tensile [...] Read more.

This study investigates the development of sustainable polymer composites for structural strengthening by incorporating waste glass fibers and natural fibers (flax and hemp) into an epoxy matrix, in response to the growing environmental concerns. Mechanical, thermal, and durability-related properties were evaluated through tensile testing, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), water absorption, and water immersion aging tests. Results showed that incorporating waste glass fibers enhanced the tensile strength and thermal decomposition temperature by 88% and 5.4%, respectively, compared to composites reinforced with solely natural fibers. Water absorption tests indicated that waste glass fiber-reinforced hybrid composites exhibited lower water uptake than flax and hemp fiber-reinforced composites. After water immersion, the tensile strength loss was recorded as 22, 25, and 8.5% for the composites reinforced with hemp, flax, and waste glass fiber, respectively. The findings confirm that incorporating waste glass fibers into natural fiber composites effectively mitigates moisture sensitivity and improves mechanical performance. Hybridizing flax and hemp fibers with waste glass fibers provides a practical and sustainable approach to enhancing composite performance, making them a viable alternative for strengthening reinforced concrete structures requiring long-term resistance. The recycled waste glass fibers employed in this study offered comparable mechanical performance while drastically lowering raw material consumption and environmental impact, in contrast to virgin glass fibers frequently used in earlier investigations. This demonstrates how recycling-oriented composite design can provide both sustainability and performance benefits. Full article

(This article belongs to the Special Issue Mechanical Response Characteristics and Performance Evaluation of Polymer Materials)

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18 pages, 4872 KiB

Open AccessArticle

Optimizing the Synthesis of CO₂-Responsive Polymers: A Kinetic Model Approach for Scaling Up

by Emil Pashayev and Prokopios Georgopanos

Polymers 2025, 17(8), 1115; https://doi.org/10.3390/polym17081115 - 20 Apr 2025

Abstract

The kinetic model is a crucial tool for optimizing polymer synthesis protocols and facilitating the scaled-up production processes of the CO₂-responsive polymer poly(N-[3-(dimethylamino)propyl]-acrylamide)-b-poly(methyl methacrylate)(PDMAPAm-b-PMMA), which is supposed to be implemented in direct air capture (DAC) technology. This study presents [...] Read more.

The kinetic model is a crucial tool for optimizing polymer synthesis protocols and facilitating the scaled-up production processes of the CO₂-responsive polymer poly(N-[3-(dimethylamino)propyl]-acrylamide)-b-poly(methyl methacrylate)(PDMAPAm-b-PMMA), which is supposed to be implemented in direct air capture (DAC) technology. This study presents a simulation of the kinetic model developed for the Reversible Addition−Fragmentation Chain-Transfer (RAFT) polymerization of N-[3-(dimethylamino)propyl]-acrylamide (DMAPAm), alongside an investigation into the kinetics of this polymerization using the simulation as an analytical tool, as well as the application of the simulation for the upscaling of RAFT polymerization. Ultimately, the kinetic model was validated through two kinetic experiments, confirming its reliability. It was subsequently employed to optimize the synthesis recipe and to predict the properties of PDMAPAm homopolymers, thereby supporting the upscaling of PDMAPAm-b-PMMA diblock copolymer synthesis. In the end, the preliminary results of the CO₂-responsiveness of the diblock copolymer were determined with a simple experiment. Full article

(This article belongs to the Special Issue Advances and Applications of Block Copolymers II)

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23 pages, 4926 KiB

Open AccessArticle

Light-Mediated 3D-Printed Wound Dressings Based on Natural Polymers with Improved Adhesion and Antioxidant Properties

by Rute Silva, Matilde Medeiros, Carlos T. B. Paula, Sofia Saraiva, Rafael C. Rebelo, Patrícia Pereira, Jorge F. J. Coelho, Arménio C. Serra and Ana C. Fonseca

Polymers 2025, 17(8), 1114; https://doi.org/10.3390/polym17081114 - 20 Apr 2025

Viewed by 45

Abstract

The lack of personalized wound dressings tailored to individual needs can significantly hinder wound healing. Hydrogels offer a promising solution, as they can be engineered to mimic the extracellular matrix (ECM), providing an optimal environment for wound repair. The integration of digital light [...] Read more.

The lack of personalized wound dressings tailored to individual needs can significantly hinder wound healing. Hydrogels offer a promising solution, as they can be engineered to mimic the extracellular matrix (ECM), providing an optimal environment for wound repair. The integration of digital light processing (DLP), a high-resolution 3D printing process, allows precise customization of hydrogel-based wound dressings. In this study, gelatin methacrylate (GelMA)-based formulations were prepared in combination with three different polymeric precursors: methacrylated hyaluronic acid (HAMA), poly (ethylene glycol) diacrylate (PEGDA) and allyl cellulose (MCCA). These precursors were used to print high-resolution micropatterned patches. The printed constructs revealed a high gel content and a good resistance to hydrolytic degradation. To improve the adhesive and antioxidant properties of the printed patches, gallic acid (GA) was incorporated through surface functionalization. This enabled the scavenging of approximately 80% of free radicals within just 4 h. The adhesive properties of the printed wound dressings were also significantly improved, with further enhancement observed upon the addition of Fe³⁺ ions. In vitro cytocompatibility tests using a fibroblast (NHDF) cell line confirmed the suitability of the materials for biomedical applications. Thus, this study demonstrates the potential of DLP-printed hydrogels as advanced personalized wound dressing materials. Full article

(This article belongs to the Special Issue Biomedical Applications of Polymeric Materials, 3rd Edition)

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21 pages, 2419 KiB

Open AccessArticle

Characterization and Kinetic Study of Agricultural Biomass Orange Peel Waste Combustion Using TGA Data

by Suleiman Mousa, Ibrahim Dubdub, Majdi Ameen Alfaiad, Mohammad Yousef Younes and Mohamed Anwar Ismail

Polymers 2025, 17(8), 1113; https://doi.org/10.3390/polym17081113 - 19 Apr 2025

Viewed by 72

Abstract

This study presents a comprehensive kinetic and thermodynamic investigation of dried orange peel (OP) combustion, employing thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) at high heating rates (20–80 K min⁻¹). This gap in high heating rate analysis motivates the novelty of [...] Read more.

This study presents a comprehensive kinetic and thermodynamic investigation of dried orange peel (OP) combustion, employing thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) at high heating rates (20–80 K min⁻¹). This gap in high heating rate analysis motivates the novelty of present study, by investigating OP combustion at 20, 40, 60, and 80 K min⁻¹ using TGA, to closely simulate rapid thermal conditions typical of industrial combustion processes. Thermal decomposition occurred in three distinct stages corresponding sequentially to the dehydration, degradation of hemicellulose, cellulose, and lignin. Activation energy (E_a) was calculated using six model-free methods—Friedman (FR), Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Starink (STK), Kissinger (K), and Vyazovkin (VY)—yielding values between 64 and 309 kJ mol⁻¹. The E_a increased progressively from the initial to final degradation stages, reflecting the thermal stability differences among biomass constituents. Further kinetic analysis using the Coats–Redfern (CR) model-fitting method identified that first-order (F1), second-order (F2), and diffusion-based mechanisms (D1, D2, D3) effectively describe OP combustion. Calculated thermodynamic parameters—including enthalpy (ΔH), Gibbs free energy (ΔG), and entropy (ΔS)—indicated the endothermic and increasingly non-spontaneous nature of the reactions at higher conversions. These findings demonstrate the potential of OP, an abundant agricultural waste product, as a viable bioenergy resource, contributing valuable insights into sustainable combustion processes. Full article

(This article belongs to the Special Issue Life Cycle and Utilization of Lignocellulosic Materials)

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15 pages, 8197 KiB

Open AccessArticle

Preparation and Characterization of Low-Molecular-Weight Polyacrylonitrile

by Yuanteng Yang, Xiaoli Jiang, Jing Jiang, Yang Liu, Lin Zhao, Hongyu Zhu, Junjie Wang, Zongkai Yan and Yagang Zhang

Polymers 2025, 17(8), 1112; https://doi.org/10.3390/polym17081112 - 19 Apr 2025

Viewed by 102

Abstract

Polyacrylonitrile (PAN) is renowned for its excellent physical and chemical properties, making it a promising candidate for producing high-performance and energetic materials. However, traditional high-molecular-weight PAN suffers from poor solubility and low reactivity, which limits its application as a precursor for advanced materials. [...] Read more.

Polyacrylonitrile (PAN) is renowned for its excellent physical and chemical properties, making it a promising candidate for producing high-performance and energetic materials. However, traditional high-molecular-weight PAN suffers from poor solubility and low reactivity, which limits its application as a precursor for advanced materials. To overcome these issues, this study successfully synthesized low-molecular-weight PAN (M_η: 6.808 kDa) using an environmentally friendly aqueous precipitation polymerization method, utilizing ammonium persulfate (6 wt% relative to the monomer mass) as the initiator and isopropanol (400 wt%) as the chain transfer agent. The structures and properties of the synthesized low-molecular-weight PAN were analyzed in depth. The morphology and chain structure of PAN were characterized using field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance hydrogen spectroscopy (¹H NMR). The thermal properties were assessed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Additionally, the state changes during the heating process of PAN with different molecular weights were directly observed using a visual melting point analyzer for the first time. Furthermore, the influence of molecular weight on PAN’s solubility was investigated in detail. Based on that, a linear regression between the viscosity average molecular weight (M_η) and the number average molecular weight (M_n) was established, providing simple and rapid access to the molecular weight of the synthesized PAN via viscosity measurements. Our study employed CTA-controlled aqueous precipitation polymerization to prepare low-molecular-weight PAN, which possesses significant potential in producing tetrazole-based energetic materials. Full article

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

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28 pages, 15740 KiB

Open AccessArticle

Enhancing Mechanical Energy Absorption of Honeycomb and Triply Periodic Minimal Surface Lattice Structures Produced by Fused Deposition Modelling in Reusable Polymers

by Alin Bustihan, Ioan Botiz, Ricardo Branco and Rui F. Martins

Polymers 2025, 17(8), 1111; https://doi.org/10.3390/polym17081111 - 19 Apr 2025

Viewed by 45

Abstract

This study investigated the mechanical energy absorption properties of polymeric lattice structures fabricated using additive manufacturing. Existing studies have primarily focused on rigid or single-use materials, with limited attention given to flexible polymers and their behaviour under repeated compressive loading. Addressing this gap, [...] Read more.

This study investigated the mechanical energy absorption properties of polymeric lattice structures fabricated using additive manufacturing. Existing studies have primarily focused on rigid or single-use materials, with limited attention given to flexible polymers and their behaviour under repeated compressive loading. Addressing this gap, the structures investigated in this study are manufactured using three flexible polymers—polyether block amide, thermoplastic polyurethane, and thermoplastic copolyester elastomer—to enhance the reusability performance. Two high-performance designs were analysed, namely honeycomb structures (inspired by pomelo peel and simply hexagonal arrangements) and 3D triply periodic minimal surface structure of the type FRD. The primary objective was to evaluate their energy absorption capacity and reusability using three repeated compression tests. These tests revealed that thermoplastic copolyester elastomer exhibited the highest energy absorption in initial impact conditions, but lower values for the following compressions. However, polyether block amide demonstrated superior reusability, maintaining a consistent energy absorption efficiency of 56.1% over multiple compression cycles. The study confirms that modifying triply periodic minimal surface structures along the z-axis enhances their absorption efficiency, with even-numbered z-parameter structures outperforming odd-numbered ones due to their complete cell structure. These findings highlight the critical role of structural geometry and material selection to optimise polymeric lattice structures for lightweight reusable energy absorption applications, such as automotive safety and impact protection. Full article

(This article belongs to the Special Issue Engineering and Medical Polymer Additive Manufacturing: Current and Future Trends)

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36 pages, 6289 KiB

Open AccessReview

Ionizing Radiation and Its Effects on Thermoplastic Polymers: An Overview

by Ary Machado de Azevedo, Pedro Henrique Poubel Mendonça da Silveira, Thomaz Jacintho Lopes, Odilon Leite Barbosa da Costa, Sergio Neves Monteiro, Valdir Florêncio Veiga-Júnior, Paulo Cezar Rocha Silveira, Domingos D’Oliveira Cardoso and André Ben-Hur da Silva Figueiredo

Polymers 2025, 17(8), 1110; https://doi.org/10.3390/polym17081110 - 19 Apr 2025

Viewed by 202

Abstract

This article explores the foundational principles of ionizing radiation and provides a comprehensive overview of its impact on thermoplastic polymers. Ionizing radiation, encompassing gamma rays, X-rays, and electron beams, has been extensively studied due to its capacity to alter the molecular structure of [...] Read more.

This article explores the foundational principles of ionizing radiation and provides a comprehensive overview of its impact on thermoplastic polymers. Ionizing radiation, encompassing gamma rays, X-rays, and electron beams, has been extensively studied due to its capacity to alter the molecular structure of polymers. These changes enable advancements in various applications by promoting molecular crosslinking, controlled degradation, molecular grafting, and crystallinity adjustments. The article delves into the fundamental mechanisms of radiation thermoplastic polymer interactions, including ionization, electronic excitation, and free radical formation. It highlights how these processes lead to structural transformations that enhance the physical, thermal, and mechanical properties of thermoplastic polymers. Factors such as radiation type, absorbed doses, temperature, and environmental conditions are discussed in the context of their role in controlling these modifications. Key practical applications are identified across fields such as medicine, food packaging, aerospace, and industry. Examples include the production of sterilizable medical devices, enhanced food packaging for longer shelf life, and radiation-resistant materials for the aerospace and nuclear sectors. Despite its many advantages, the article also emphasizes challenges such as process variability, polymer sensitivity to radiation, and standardization difficulties. The review underscores emerging research directions, including optimizing irradiation parameters and integrating advanced characterization techniques like Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray diffraction (XRD). The development of new polymer blends and composites, designed for irradiation-induced property enhancement, represents a promising area of innovation. Full article

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

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12 pages, 10201 KiB

Open AccessArticle

Effect of Resin Parameters on the Consistency and Mechanical Properties of Ultra-High-Molecular-Weight Polyethylene Fiber

by Cheng Yan, Tiantian Yan, Tianhong Dong, Mingxin Xia, Yumin Xia and Yong He

Polymers 2025, 17(8), 1109; https://doi.org/10.3390/polym17081109 - 19 Apr 2025

Viewed by 83

Abstract

Maintaining the consistency of linear density in ultra-high-molecular-weight polyethylene (UHMWPE) fiber has been a critical challenge in the production of UHMWPE fibers. However, there has been limited research focusing on the impact of UHMWPE resin parameters on the consistency in fiber linear density. [...] Read more.

Maintaining the consistency of linear density in ultra-high-molecular-weight polyethylene (UHMWPE) fiber has been a critical challenge in the production of UHMWPE fibers. However, there has been limited research focusing on the impact of UHMWPE resin parameters on the consistency in fiber linear density. In this study, a series of UHMWPE fibers were produced through wet spinning using UHMWPE resins with varying parameters. The effects of molecular weight, molecular weight distribution, particle size, and particle size distribution of UHMWPE resins on the consistency of linear density and the mechanical properties of UHMWPE fibers were systematically investigated. The experimental findings revealed that narrowing the molecular weight distribution and particle size distribution of ultra-high molecular weight polyethylene (UHMWPE) resin precursors significantly enhanced the consistency of resultant UHMWPE fibers, concurrently improving their tensile strength and elastic modulus. Notably, while the absolute molecular weight of the resin demonstrated no statistically significant correlation with fiber consistency, an optimal molecular weight range was identified to maximize the mechanical performance of UHMWPE fibers. Specifically, fibers synthesized from resin precursors within this molecular weight window exhibited peak values in both strength and modulus, suggesting a critical balance between molecular chain entanglement and processability. Full article

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

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27 pages, 533 KiB

Open AccessReview

Physics-Informed Neural Networks in Polymers: A Review

by Ivan Malashin, Vadim Tynchenko, Andrei Gantimurov, Vladimir Nelyub and Aleksei Borodulin

Polymers 2025, 17(8), 1108; https://doi.org/10.3390/polym17081108 - 19 Apr 2025

Viewed by 49

Abstract

The modeling and simulation of polymer systems present unique challenges due to their intrinsic complexity and multi-scale behavior. Traditional computational methods, while effective, often struggle to balance accuracy with computational efficiency, especially when bridging the atomistic to macroscopic scales. Recently, physics-informed neural networks [...] Read more.

The modeling and simulation of polymer systems present unique challenges due to their intrinsic complexity and multi-scale behavior. Traditional computational methods, while effective, often struggle to balance accuracy with computational efficiency, especially when bridging the atomistic to macroscopic scales. Recently, physics-informed neural networks (PINNs) have emerged as a promising tool that integrates data-driven learning with the governing physical laws of the system. This review discusses the development and application of PINNs in the context of polymer science. It summarizes the recent advances, outlines the key methodologies, and analyzes the benefits and limitations of using PINNs for polymer property prediction, structural design, and process optimization. Finally, it identifies the current challenges and future research directions to further leverage PINNs for advanced polymer modeling. Full article

(This article belongs to the Special Issue Scientific Machine Learning for Polymeric Materials)

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25 pages, 3353 KiB

Open AccessArticle

Thermo-Physical Behaviour of Thermoplastic Composite Pipe for Oil and Gas Applications

by Obinna Okolie, Nadimul Haque Faisal, Harvey Jamieson, Arindam Mukherji and James Njuguna

Polymers 2025, 17(8), 1107; https://doi.org/10.3390/polym17081107 - 19 Apr 2025

Viewed by 154

Abstract

Thermoplastic composite pipes (TCP) consist of three distinct layers—liner, reinforcement, and coating—offering superior advantages over traditional industrial pipes, including flexibility, lightweight construction, and corrosion resistance. This study systematically characterises the thermal properties of TCP layers and their compositions using a multi-method approach. Thermal [...] Read more.

Thermoplastic composite pipes (TCP) consist of three distinct layers—liner, reinforcement, and coating—offering superior advantages over traditional industrial pipes, including flexibility, lightweight construction, and corrosion resistance. This study systematically characterises the thermal properties of TCP layers and their compositions using a multi-method approach. Thermal analysis was conducted through differential scanning calorimetry (DSC) for isothermal and non-isothermal crystallisation, thermogravimetric analysis (TGA) for thermal stability, and Fourier transform infrared spectroscopy (FTIR) for material identification. FTIR confirmed polyethylene as the primary component of TCP, with compositional variations across the layers. TGA results indicated that thermal degradation begins at approximately 200 °C, with complete decomposition at 500 °C. DSC analysis revealed a double melting peak, prompting further investigation into its mechanisms. On-isothermal crystallisation kinetics, analysed at cooling rates of 10 °C/min and 50 °C/min, revealed an anisotropic crystalline growth pattern. Although nucleation occurs uniformly, the subsequent three-dimensional crystalline growth is governed more by the degree of supercooling than by the crystallography of the glass fibres. This underscores the importance of precisely controlling the cooling rate during manufacturing to optimise the anisotropic properties of the reinforced layer. This study also demonstrates the value of FTIR, TGA, and DSC techniques in characterising the thermo-physical behaviour of TCP, offering critical insights into thermal expansion, shrinkage phenomena, and overall material stability. Given the limited body of research on this specific TCP formulation, the findings presented here lay a foundation for both quality enhancement and process optimisation. Moreover, the paper offers a distinctive perspective on the dynamic behaviour, thermal expansion, and long-term performance of TCP in demanding oil and gas environments. Full article

(This article belongs to the Section Polymer Applications)

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16 pages, 2621 KiB

Open AccessArticle

FIMOFs: Fiber-Integrated Metal–Organic Frameworks Through Electrospinning

by Mine G. Ucak-Astarlioglu, P. U. Ashvin Iresh Fernando, Spencer A. Spane, Sulymar A. Rodriguez, Gilbert K. Kosgei, Charles A. Weiss, Jr., Ivan P. Beckman, Byron Villacorta, Sasan Nouranian and Ahmed Al-Ostaz

Polymers 2025, 17(8), 1106; https://doi.org/10.3390/polym17081106 - 19 Apr 2025

Viewed by 82

Abstract

Green synthesis plays a crucial role in advancing sustainability within materials science. This study explores the integration of metal–organic frameworks (MOFs), obtained through green synthesis, using an electrospinning post-processing technique to develop MOF-based composite materials. The resulting novel multifunctional composites demonstrate enhanced stability [...] Read more.

Green synthesis plays a crucial role in advancing sustainability within materials science. This study explores the integration of metal–organic frameworks (MOFs), obtained through green synthesis, using an electrospinning post-processing technique to develop MOF-based composite materials. The resulting novel multifunctional composites demonstrate enhanced stability and functionality, compared to their control counterparts. The integration of four types of MOFs into an electrospun fiber network was investigated using a specific polymer solution. Characterization and preliminary adsorption studies were conducted to elucidate the chemistry, morphology, and adsorptive capabilities of the resulting MOF composites. Electrospinning MOFs into polymer fibers improved their stability and dye removal capabilities. More specifically, optimization of MOF-to-polymer ratios and processing conditions yielded composites that are thermally stable, with modified surface area and porosity. Post-processing MOFs resulted in a fiber diameter increase of 44 and 109%, enhancing the composites by providing more MOF active sites and improved mechanical strength. Zirconium-based post-processed MOFs demonstrated superior dye removal, different from the copper-based dyes. Electrospinning technology has demonstrated significant potential in the fabrication of high-performance multifunctional MOF composites. This has helped to create advanced sustainable composites with tailored properties, paving the way for more targeted and efficient applications. The applications of these composites show promise for military engineering where durable, light weight, and multifunctional materials are critical in contributing to improved performance, operational efficiency, and safety. Full article

(This article belongs to the Section Polymer Fibers)

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10 pages, 3451 KiB

Open AccessArticle

Stretchable and Wearable Sensors for Contact Touch and Gesture Recognition Based on Poling-Free Piezoelectric Polyester Elastomer

by Kaituo Wu, Wanli Zhang, Qian Zhang and Xiaoran Hu

Polymers 2025, 17(8), 1105; https://doi.org/10.3390/polym17081105 - 19 Apr 2025

Viewed by 157

Abstract

Human–computer interaction (HCI) enables communication between humans and computers, which is widely applied in various fields such as consumer electronics, education, medical rehabilitation, and industrial control. Human motion monitoring is one of the most important methods of achieving HCI. In the present work, [...] Read more.

Human–computer interaction (HCI) enables communication between humans and computers, which is widely applied in various fields such as consumer electronics, education, medical rehabilitation, and industrial control. Human motion monitoring is one of the most important methods of achieving HCI. In the present work, a novel human motion monitoring sensor for contact touch and gesture recognition is fabricated based on polyester elastomer (PTE) synthesized from diols and diacids, with both piezoelectric and triboelectric properties. The PTE sensor can respond to contacted and contactless me-chemical signals by piezoelectric and triboelectric responding, respectively, which enables simultaneous touch control and gesture recognition. In addition, the PTE sensor presents high stretchability with elongation at break over 1000% and high durability over 4000 impact cycles, offering significant potential for consumer electronics and wearable devices. Full article

(This article belongs to the Special Issue Polymer-Based Smart Materials: Preparation and Applications)

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8 pages, 193 KiB

Open AccessEditorial

Advances in Wood-Based Composites

by Lubos Kristak, Roman Reh, Marius Catalin Barbu and Eugenia Mariana Tudor

Polymers 2025, 17(8), 1104; https://doi.org/10.3390/polym17081104 - 18 Apr 2025

Viewed by 101

Abstract

The significance of wood-based composites has grown substantially in recent years due to their enhanced material efficiency, sustainability, and versatile applications [...] Full article

(This article belongs to the Special Issue Advances in Wood Based Composites)

21 pages, 3382 KiB

Open AccessArticle

Producing Aerogels from Rice Straw Cellulose Obtained by a Green Method and Its Starch Blending

by Pedro A. V. Freitas, Paula Alonso Collado, Chelo González-Martínez and Amparo Chiralt

Polymers 2025, 17(8), 1103; https://doi.org/10.3390/polym17081103 - 18 Apr 2025

Viewed by 76

Abstract

Cellulose and starch–cellulose composite aerogels were obtained using green cellulose from rice straw (RS) purified with a more environmentally friendly process. Pure starch aerogels were also obtained for comparison purposes. The effect of the aerogel cross-linking with polyamideamine-epichlorohydrin (PAE) was also analysed. The [...] Read more.

Cellulose and starch–cellulose composite aerogels were obtained using green cellulose from rice straw (RS) purified with a more environmentally friendly process. Pure starch aerogels were also obtained for comparison purposes. The effect of the aerogel cross-linking with polyamideamine-epichlorohydrin (PAE) was also analysed. The properties of the cellulose aerogels were in the range of those reported using other RS cellulose fibres with similar compositions. Blending with starch implied a decrease in the liquid water absorption capacity but an increase in the mechanical strength, flexibility, and oil absorption capacity, compared to pure cellulose aerogels. Cross-linking with PAE promoted the water adsorption capacity of all aerogels and the oil absorption capacity and mechanical strength of cellulose aerogels. However, PAE did not benefit the strength and oil absorption capacity of aerogels containing starch due to their specific interactions that negatively affect the aerogel structure. Therefore, it was possible to obtain cellulose and cellulose–starch composite aerogels from RS green cellulose with modulated properties for different applications. Full article

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

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14 pages, 4139 KiB

Open AccessArticle

Catalytic Conversion of Xylo-Oligomers to Furfural in Pulping Pre-Hydrolysis Liquor Using a Hydroxyl-Functionalized Covalent Organic Framework

by Kai Zhang, Huanmei Xia, Guangyao Cheng, Peng Gan, Yuan Ju, Baozhen Guo, Jingli Yang, Chengcheng Qiao, Jixiang Lin and Jiachuan Chen

Polymers 2025, 17(8), 1102; https://doi.org/10.3390/polym17081102 - 18 Apr 2025

Viewed by 104

Abstract

With the rapid development of biorefinery technology, the efficient conversion of lignocellulose into high-value platform chemicals is of great significance for enhancing the value of renewable carbon resources. In this study, a hydroxyl-functionalized covalent organic framework (COF), TAPB-DHPA, was synthesized via an in [...] Read more.

With the rapid development of biorefinery technology, the efficient conversion of lignocellulose into high-value platform chemicals is of great significance for enhancing the value of renewable carbon resources. In this study, a hydroxyl-functionalized covalent organic framework (COF), TAPB-DHPA, was synthesized via an in situ method and innovatively applied to the catalytic conversion of xylo-oligosaccharides (XOS) into furfural. The results demonstrated that TAPB-DHPA possesses a large specific surface area, a well-developed porous structure, and excellent thermal stability, with abundant Brønsted acid (B acid) sites, exhibiting outstanding catalytic activity. Under optimal conditions, including a catalyst loading of 0.16 wt%, a reaction temperature of 180 °C, and a reaction time of 3 h, a furfural yield of up to 65.4% was achieved. The high selectivity was primarily attributed to the p-π conjugation effect between the benzene ring and the phenolic hydroxyl group, which enhanced the ionization ability of hydroxyl hydrogen, thereby effectively promoting the hydrolysis of XOS and subsequent dehydration. Furthermore, TAPB-DHPA exhibited excellent recyclability and stability, maintaining a furfural yield of over 59.9% after six cycles. This study provides new insights into the application of functionalized COF in biomass catalytic conversion and contributes to the green transformation of the pulp and paper industry into a biorefinery-based model. Full article

(This article belongs to the Section Polymer Chemistry)

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17 pages, 2458 KiB

Open AccessArticle

NIR pH-Responsive PEGylated PLGA Nanoparticles as Effective Phototoxic Agents in Resistant PDAC Cells

by Degnet Melese Dereje, Francesca Bianco, Carlotta Pontremoli, Alessandra Fiorio Pla and Nadia Barbero

Polymers 2025, 17(8), 1101; https://doi.org/10.3390/polym17081101 - 18 Apr 2025

Viewed by 127

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers worldwide due to its resistance to conventional therapies that is attributed to its dense and acidic tumor microenvironment. Chemotherapy based on gemcitabine usually lacks efficacy due to poor drug penetration and the metabolic [...] Read more.

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers worldwide due to its resistance to conventional therapies that is attributed to its dense and acidic tumor microenvironment. Chemotherapy based on gemcitabine usually lacks efficacy due to poor drug penetration and the metabolic characteristics of the cells adapted to grow at a more acidic pH_e, thus presenting a more aggressive phenotype. In this context, photodynamic therapy (PDT) offers a promising alternative since it generally does not suffer from the same patterns of cross-resistance observed with chemotherapy drugs. In the present work, a novel bromine-substituted heptamethine-cyanine dye (BrCY7) was synthesized, loaded into PEG-PLGA NPs, and tested on the pancreatic ductal adenocarcinoma cell line cultured under physiological (PANC-1 CT) and acidic (PANC-1 pH selected) conditions, which promotes the selection of a more aggressive phenotype. The cytotoxicity of BrCY7-PEG-PLGA is dose-dependent, with an IC₅₀ of 2.15 µM in PANC-1 CT and 2.87 µM in PANC-1 pH selected. Notably, BrCY7-PEG-PLGA demonstrated a phototoxic effect against PANC-1 pH selected cells but not on PANC-1 CT, which makes these findings particularly relevant since PANC-1 pH selected cells are more resistant to gemcitabine as compared with PANC-1 CT cells. Full article

(This article belongs to the Special Issue Biomedical Applications of Polymeric Materials, 3rd Edition)

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30 pages, 34143 KiB

Open AccessReview

Incorporation of Carbocyclic Moieties into Polymer Structure: A Powerful Way to Polymers with Increased Microporosity

by Maxim A. Zotkin, Kirill V. Zaitsev and Dmitry A. Alentiev

Polymers 2025, 17(8), 1100; https://doi.org/10.3390/polym17081100 - 18 Apr 2025

Viewed by 186

Abstract

Microporous soluble polymers attract great attention as materials for membrane gas separation, gas storage and transportation, as sorbents, supports for catalysts, and matrices for mixed matrix membranes. The key problems in the development of this area of polymer chemistry include the search for [...] Read more.

Microporous soluble polymers attract great attention as materials for membrane gas separation, gas storage and transportation, as sorbents, supports for catalysts, and matrices for mixed matrix membranes. The key problems in the development of this area of polymer chemistry include the search for methods of controlling the porous structure parameters and ensuring the stability of their properties over time. In this connection, a fruitful approach is to introduce bulky and rigid, often framework carbocyclic moieties into the polymer backbones and side chains. This review discusses the effect of carbocyclic moieties on gas transport properties, BET surface area, and FFV of glassy polymers, such as polyacetylenes, polynorbornenes, polyimides, and ladder and partially ladder polymers. In the majority of cases, the incorporation of carbocyclic moieties makes it possible to controllably increase these three parameters. Carbocyclic moieties can also improve CO₂/gas separation selectivity, which is displayed for ladder polymers and polynorbornenes. Full article

(This article belongs to the Special Issue Advanced Polymer Materials: Synthesis, Structure, and Properties)

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26 pages, 22416 KiB

Open AccessArticle

Theoretical and Experimental Study on the Surface Microstructures of Polyimide in Ultra-Precision Fly-Cutting

by Jie Liu, Sheng Wang and Qingliang Zhao

Polymers 2025, 17(8), 1099; https://doi.org/10.3390/polym17081099 - 18 Apr 2025

Viewed by 156

Abstract

Polyimide (PI) with surface microstructures has broad application prospects in aerospace, integrated circuits, and optical engineering due to its excellent mechanical properties, high thermal stability, and chemical resistance. Ultra-precision fly-cutting (UPFC) is a promising advanced technique for machining PI microstructures. However, few studies [...] Read more.

Polyimide (PI) with surface microstructures has broad application prospects in aerospace, integrated circuits, and optical engineering due to its excellent mechanical properties, high thermal stability, and chemical resistance. Ultra-precision fly-cutting (UPFC) is a promising advanced technique for machining PI microstructures. However, few studies on the UPFC of PI materials are reported. In this study, the machining principle of UPFC is analyzed, and a comparative study of different processing strategies is conducted. The experimental results demonstrate that the climb cutting strategy is more suitable for PI microstructure machining, which can significantly reduce burr formation and achieve lower surface roughness. The theoretical models describing tool motion and predicting maximum chip thickness in UPFC are established, and the predicted chip thickness is consistent with the experimental results. Moreover, the influence of process parameters on the surface morphology and dimensional accuracy of microstructures is assessed through a series of experiments. The results indicate that cutting depth and step-over are the dominant factors influencing dimensional accuracy and surface roughness. Furthermore, the cutting force during UPFC is extremely small, only in the range of millinewtons (mN). In addition, the cutting force in the feed direction exhibits a high sensitivity to variations in process parameters compared to other directional components. This study provides theoretical guidance for the establishment of a theoretical model and the selection of UPFC process parameters for fabricating PI microstructures. Full article

(This article belongs to the Special Issue Polymer Manufacturing Processes)

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