Polymers

13 pages, 2920 KB

Open AccessArticle

Tuning the Structure of Poly(aspartic acid)s’ Self-Assemblies to Enhance Cellular Uptake

by Jimin Jeong, Junwoo Lim, Sungwoo Cho, Sa Ra Han, Suk Hyeon Hong and Jae Hyun Jeong

Polymers 2025, 17(17), 2373; https://doi.org/10.3390/polym17172373 (registering DOI) - 31 Aug 2025

Self-assembled nanoparticles formed with amphiphilic block or graft copolymers are being extensively studied for their use in a variety of biological and industrial applications, including targeted drug delivery. This study reports a novel strategy to tune the structure of self-assembled nanoparticles for enhancing [...] Read more.

Self-assembled nanoparticles formed with amphiphilic block or graft copolymers are being extensively studied for their use in a variety of biological and industrial applications, including targeted drug delivery. This study reports a novel strategy to tune the structure of self-assembled nanoparticles for enhancing the cellular uptake by varying the hydrophilic ratio of amphiphilic graft copolymers. We synthesized poly(aspartic acid) (PAsp) substituted with octadecyl chains (C18) at varying degrees of substitution (DS), ranging from 4.5 to 37.5 mol%, which could form self-assemblies in an aqueous solution. As the DS increased, a morphological transition was observed—from spherical assemblies (DS 4.5 and 9.1) to rod-like (DS 19.0), vesicular (DS 25.7), and lamellar-like structures (DS 37.6). Further, Trans-Activator of Transcription (TAT) as the cell penetrating peptide to the synthesized amphiphilic graft copolymers leads to an enhanced cellular uptake of the biomimetic self-assembly. In particular, the lamellar-like self-assemblies resulted in a 1.3-fold increase of cellular uptake, as compared to the spherical self-assemblies, and a 3.6-fold increase, as compared to the vesicles. Therefore, tuning the structure of poly(aspartic acid)s’ self-assemblies was proven as an effective strategy to enhance the cellular uptake, while minimizing invasive cell damage. This new strategy to tune the morphologies of self-assemblies will serve to improve the cell penetrating activity for targeted drug delivery. Full article

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20 pages, 6816 KB

Open AccessArticle

Development of Graphene/Recycled Carbon Fiber-Reinforced PLA Composites for MEX Printing and Dry Machinability Analysis

by Abdullah Yahia AlFaify, Mustafa Saleh, Saqib Anwar, Abdulrahman M. Al-Ahmari and Abd Elaty E. AbdElgawad

Polymers 2025, 17(17), 2372; https://doi.org/10.3390/polym17172372 (registering DOI) - 31 Aug 2025

Abstract

Material extrusion (MEX) is an additive manufacturing process used for 3D printing thermoplastic-based polymers, including single polymers, blends, and reinforced polymer composites (RPCs). RPCs are highly valued in various industries for their exceptional properties. The surface finish of RPC MEX-printed parts is high [...] Read more.

Material extrusion (MEX) is an additive manufacturing process used for 3D printing thermoplastic-based polymers, including single polymers, blends, and reinforced polymer composites (RPCs). RPCs are highly valued in various industries for their exceptional properties. The surface finish of RPC MEX-printed parts is high due to the process-related layering nature and the materials’ properties. This study explores RPC development for MEX printing and the potential of dry milling post-processing to enhance the MEX-printed part’s surface quality. RPC MEX filaments were developed by incorporating graphene nanoplatelets (GNPs) and/or recycled-carbon fibers (rCFs) into a polylactic acid (PLA) matrix. The filaments, including pure PLA and various GNPs-PLA composites, rCF-PLA, and rCF-GNPs-PLA, were developed through ball mill mixing and melt extrusion. Tensile tests were performed to assess the mechanical properties of the developed materials. Dry milling post-processing was carried out to assess the machinability, with the aim of enhancing the MEX-printed part’s surface quality. The results revealed that adding GNPs into PLA showed no considerable enhancements in the tensile properties of the fabricated RPCs, which is contrary to several existing studies. Dry milling showed an enhanced surface quality of MEX-printed parts in terms of surface roughness (Sa and Sz) and the absence of defects such as delamination and layer lines. Adding GNPs into PLA facilitated the dry machining of PLA, resulting in reduced surface asperities compared to pure PLA. Also, there was no observation of pulled-out, realigned, or naked rCFs, which indicates good machinability. Adding GNPs also suppressed the formation of voids around the rCFs during the dry milling. This study provides insights into machining 3D-printed polymer composites to enhance their surface quality. Full article

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18 pages, 1341 KB

Open AccessArticle

Upcycling Walnut Green Husk: Polyphenol-Rich Extracts from Traditional vs. Organic Crops for Spray-Dried Vegan Additive Development

by Silvia Matiacevich, Ignacio Durán, Marlen Gutiérrez-Cutiño, Javier Echeverría, César Echeverría and Daniela Soto-Madrid

Polymers 2025, 17(17), 2371; https://doi.org/10.3390/polym17172371 (registering DOI) - 31 Aug 2025

Abstract

This study explores the valorization of walnut green husk, an agro-industrial by-product, through ultrasound-assisted extraction to obtain polyphenol-rich extracts with antioxidant properties. The extracts demonstrated non-cytotoxicity, regardless of the presence of pesticides, antibiotics, or the type of crop. Notably, organic walnut husk yielded [...] Read more.

This study explores the valorization of walnut green husk, an agro-industrial by-product, through ultrasound-assisted extraction to obtain polyphenol-rich extracts with antioxidant properties. The extracts demonstrated non-cytotoxicity, regardless of the presence of pesticides, antibiotics, or the type of crop. Notably, organic walnut husk yielded higher total polyphenols and antioxidant activity, identifying 37 polyphenolic compounds compared to 22 in traditional crops. Chickpea protein was utilized as a wall material to encapsulate the extract, resulting in a sustainable, vegan antioxidant powder. Optimal results were achieved using 5% (w/v) chickpea protein and spray drying at 136 °C, yielding a light-colored powder with high antioxidant content and stability under low humidity (≤35%). The product shows promise as a natural, plant-based alternative to synthetic antioxidants in food systems. Further studies are needed to evaluate its functional and technological performance during food integration and storage. Full article

(This article belongs to the Special Issue Advanced Study on Natural Polymers and Their Applications)

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19 pages, 14199 KB

Open AccessArticle

Synthesis and Fabrication of Dialdehyde Cellulose/PVA Films Incorporating Carbon Quantum Dots for Active Packaging Applications

by Tanpong Chaiwarit, Rangsan Panyathip, Sastra Yuantrakul, Kwanjit Duangsonk, Pattaraporn Panraksa, Pornchai Rachtanapun, Kittisak Jantanasakulwong and Pensak Jantrawut

Polymers 2025, 17(17), 2370; https://doi.org/10.3390/polym17172370 (registering DOI) - 30 Aug 2025

Abstract

Active packaging supports sustainable development by extending food shelf life and reducing spoilage, contributing to global food security. In this study, cellulose dialdehyde was synthesized and blended with polyvinyl alcohol in varying ratios to produce composite films. The incorporation of dialdehyde cellulose into [...] Read more.

Active packaging supports sustainable development by extending food shelf life and reducing spoilage, contributing to global food security. In this study, cellulose dialdehyde was synthesized and blended with polyvinyl alcohol in varying ratios to produce composite films. The incorporation of dialdehyde cellulose into films tended to increase puncture strength and Young’s modulus, decrease elongation, reduce water solubility, and enhance resistance to water vapor transmission because of crosslinking. Carbon quantum dots were subsequently incorporated into composite films to enhance their antibacterial property. This represents a novel combination of a natural bio-based crosslinker and fluorescent nanomaterials in a single packaging system. Carbon quantum dots were synthesized by an electrochemical method and incorporated as functional agents. The addition of carbon quantum dots influenced the mechanical properties of the films due to interactions between polymers and carbon quantum dots. This interaction also slightly reduced the antibacterial effectiveness of the films, consisting of dialdehyde cellulose and PVA in ratios of 3:1 and 4:0. Nevertheless, the composite films maintained sufficient antimicrobial activity against common foodborne bacteria, including Staphylococcus aureus, Escherichia coli, and Salmonella Typhimurium. Overall, the findings demonstrate that multifunctional material made from dialdehyde cellulose, polyvinyl alcohol, and carbon quantum dots are a promising alternative to conventional plastic packaging. Full article

(This article belongs to the Section Polymer Applications)

14 pages, 3153 KB

Open AccessArticle

Three-Dimensional-Printed Polymer–Polymer Composite Electrolytes for All-Solid-State Li Metal Batteries

by Hao Wang, Xin Xiong, Huie Hu and Sijie Liu

Polymers 2025, 17(17), 2369; https://doi.org/10.3390/polym17172369 (registering DOI) - 30 Aug 2025

Abstract

High-performance batteries for military and extreme environment applications require alternatives to conventional liquid lithium-ion batteries (LIBs), which suffer from poor low-temperature performance and safety risks. All-solid-state lithium batteries (ASSLBs) offer enhanced safety and superior low-temperature capability. In this work, we designed and fabricated [...] Read more.

High-performance batteries for military and extreme environment applications require alternatives to conventional liquid lithium-ion batteries (LIBs), which suffer from poor low-temperature performance and safety risks. All-solid-state lithium batteries (ASSLBs) offer enhanced safety and superior low-temperature capability. In this work, we designed and fabricated composite solid-state electrolytes using polyvinylidene fluoride (PVDF) and polyacrylic acid (PAA) as polymer matrices, N,N-dimethylformamide (DMF) as the solvent, and lithium bis(trifluoromethane sulfonimide) (LiTFSI) as the lithium salt. Composite solutions with varying PAA mass ratios were prepared. Advanced three-dimensional (3D) printing technology enabled the rapid and precise fabrication of electrolyte membranes. An ionic conductivity of about 2.71 × 10⁻⁴ S cm⁻¹ at 25 °C, high mechanical strength, and good thermal properties can be achieved through component and 3D printing process optimization. Assembled LiCoO₂||PVDF@PAA||Li ASSLBs delivered an initial discharge capacity of 165.3 mAh/g at 0.1 mA cm⁻² (room temperature), maintaining 98% capacity retention after 300 cycles. At 0 °C, these cells provided 157.4 mAh/g initial capacity with 85% retention over 100 cycles at 0.1 mA cm⁻². This work identifies the optimal PAA ratio for enhanced electrochemical performance and demonstrates the viability of 3D printing for advanced ASSLB manufacturing. Full article

(This article belongs to the Special Issue Advances in Polymeric Additive Manufacturing—2nd Edition)

25 pages, 1192 KB

Open AccessArticle

Effect of Biobased and Mineral Additives on the Properties of Recycled Polypropylene Packaging Materials

by Wiktor Wyderkiewicz, Robert Gogolewski, Justyna Miedzianowska-Masłowska, Konrad Szustakiewicz and Marcin Masłowski

Polymers 2025, 17(17), 2368; https://doi.org/10.3390/polym17172368 (registering DOI) - 30 Aug 2025

Abstract

The recycling of polypropylene (PP) packaging films modified with biobased additives: biochar derived from the pyrolysis of natural fibers and diatomaceous earth was investigated. The aim was to assess the impact of these modifiers on the processing, rheological, mechanical, and thermal properties of [...] Read more.

The recycling of polypropylene (PP) packaging films modified with biobased additives: biochar derived from the pyrolysis of natural fibers and diatomaceous earth was investigated. The aim was to assess the impact of these modifiers on the processing, rheological, mechanical, and thermal properties of the recycled material. The processing behavior was evaluated through extrusion with granulation to determine industrial applicability. Rheological properties, including viscosity and melt flow index (MFI), were measured to characterize flow behavior. Mechanical performance was assessed through tensile strength, hardness, three-point bending, and impact resistance tests. Thermal properties were analyzed using thermogravimetric analysis (TGA), Vicat softening temperature (VST), and differential scanning calorimetry (DSC). The results demonstrate that incorporating biochar and diatomaceous earth can modify and, in selected cases, enhance the processing and performance characteristics of recycled PP films, though their impact on thermal behavior is parameter-specific. While diatomaceous earth slightly increased the onset of thermal degradation (T₅), both fillers caused a slight decrease in the VST, indicating reduced heat resistance under load. Diatomaceous earth was found to effectively improve stiffness and impact strength, while biochar reduced viscosity and promoted finer crystalline structures. Both additives acted as nucleating agents, increasing crystallization temperatures, with diatomaceous earth additionally delaying thermal degradation onset. These findings highlight the potential of using sustainable, waste-derived additives in polymer recycling, supporting the development of environmentally responsible materials within circular economy frameworks. Full article

(This article belongs to the Special Issue Natural Additive-Enhanced Polymer Composites)

14 pages, 442 KB

Open AccessArticle

Enhancing Jabon (Anthocephalus cadamba) Laminated Board Properties with Impregnation of Citric Acid, Boric Acid, and Polystyrene

by Rudi Hartono, Raynata Andini Br Tarigan, Muhammad Navis Rofii, Ihak Sumardi, Aprilia Kartikawati, Jajang Sutiawan, Falah Abu and A. M. Radzi

Polymers 2025, 17(17), 2367; https://doi.org/10.3390/polym17172367 (registering DOI) - 30 Aug 2025

Abstract

A good way to produce large-sized wood products from small-diameter logs is by using laminated boards. The lamina undergoes an impregnation pretreatment to improve its quality before being formed into laminated boards (LBs). This research was performed to analyze the effects of an [...] Read more.

A good way to produce large-sized wood products from small-diameter logs is by using laminated boards. The lamina undergoes an impregnation pretreatment to improve its quality before being formed into laminated boards (LBs). This research was performed to analyze the effects of an impregnation treatment on Jabon lamina with citric acid, boric acid, and polystyrene solutions on the physical and mechanical properties of Jabon LB. The Jabon lamina was first pretreated with citric acid, boric acid, and polystyrene by vacuuming for 30 min and pressing for 30 min at a pressure of 6.6 bar. The laminas were glued using isocyanate adhesive with a spreading rate of 280 g/m², consisting of three layers, which were cold pressed for 24 h. LB’s physical and mechanical properties were affected by the nature of the impregnating agent. Impregnating the lamina with citric acid and boric acid increased the density and moisture content of the laminated board, decreasing its mechanical properties. On the contrary, polystyrene-impregnated LB improved. After soaking in hot water, no LB displayed delamination, indicating high bonding performance. The best impregnating agent for lamina pretreatment was polystyrene, followed by boric acid and citric acid. The chemical compound, functional group, and degree of crystallinity of treated Jabon LB all changed due to the impregnation process. Full article

(This article belongs to the Special Issue Advances in Wood Based Composites, 2nd Edition)

11 pages, 913 KB

Open AccessCommunication

Upcycling Leather Waste Through Zero-Waste Hydrolysis for Versatile 3D Printable Composites

by Giovanni Venturelli, Luca Guida and Marinella Levi

Polymers 2025, 17(17), 2366; https://doi.org/10.3390/polym17172366 (registering DOI) - 30 Aug 2025

Abstract

The leather industry produces a substantial amount of solid waste, which is frequently disposed of via incineration or landfilling. While hydrolysis offers a valuable and sustainable method to chemically recycle leather waste, both acidic and alkaline processes present challenges due to the salts [...] Read more.

The leather industry produces a substantial amount of solid waste, which is frequently disposed of via incineration or landfilling. While hydrolysis offers a valuable and sustainable method to chemically recycle leather waste, both acidic and alkaline processes present challenges due to the salts produced during neutralization. This study aims to upcycle leather scraps through hydrolysis, producing a powdered filler for versatile composites suitable for both LCD vat photopolymerization and Direct Ink Writing 3D printing technologies. A zero-waste hydrolysis process was adopted using sulfuric acid neutralized with calcium hydroxide, achieving a yield of 91.3%. The composites featured a matrix composed of polyethylene-glycol-diacrylate and glycerol dimethacrylate, with embedded leather hydrolysate powder at concentrations up to 20% w/w_matrix. Tensile tests conducted on neat resin and composites demonstrated the strengthening effect of leather hydrolysate filler. Additionally, rheological tests displayed a viscoelastic behavior suitable for the adopted 3D printing technologies. The composites were successfully 3D-printed using both Direct Ink Writing and vat photopolymerization techniques, showing promising printing accuracy. This work demonstrates the potential of valorizing leather waste, upcycled via a hydrolysis method, to produce composites suitable for additive manufacturing to advance the sustainability and the circularity of the fashion sector. Full article

(This article belongs to the Special Issue Sustainable and Circular Polymer Composites for Additive Manufacturing)

26 pages, 3290 KB

Open AccessArticle

Numerical Analysis on Mechanical Properties of Different Fiber-Reinforced Cold-Formed Steel–Concrete Composite Corner Columns

by Mengyao Li, Yi Hu, Lanzhe Rao, Liqiang Jiang, Jingbin Li, Shizhong Zhou, Hongyu Sun, Shi Peng, Xia Pang, Yuanjun Chen, Jun Hu and Ping Xie

Polymers 2025, 17(17), 2365; https://doi.org/10.3390/polym17172365 (registering DOI) - 30 Aug 2025

Abstract

To overcome brittle failure in conventional cold-formed steel–concrete (CFS-C) corner columns, this paper used fiber-reinforced concrete to replace ordinary concrete, investigating failure mechanisms and performance through systematic numerical simulations. A finite element model (FEM) was established and validated by experiments, and the errors [...] Read more.

To overcome brittle failure in conventional cold-formed steel–concrete (CFS-C) corner columns, this paper used fiber-reinforced concrete to replace ordinary concrete, investigating failure mechanisms and performance through systematic numerical simulations. A finite element model (FEM) was established and validated by experiments, and the errors for ultimate capacity were within 10%. A series of numerical models was established for parametric analyses focusing on the effects of the parameters of polypropylene fiber (PF), carbon fiber (CF), steel fiber (SF), and bamboo fiber (BF) with different volume dosages and the thickness of cold-formed steel (CFS) on the axial compression ultimate capacity and corresponding displacement of CFS composite corner columns. The results indicated that (1) PF effectiveness was dependent on steel thickness: thicker steel suppressed micro-defects, activated the toughening potential of PF, and increased the ultimate capacity of the columns by 24.8%. (2) CF had a critical dosage of 0.4%: at this dosage, CF increased the column’s ultimate capacity by 14.1% through stress redistribution, while when the dosage exceeded this value, fiber agglomeration caused a reduction in the column’s strength, with a maximum decrease of 16.2%. (3) SF effectiveness showed a linear increase: at a dosage of 1.6%, SF formed a synergistic three-dimensional bridging network and generated a confinement effect, increasing the column’s ultimate capacity by 36.5% and displacement by 92.2%. (4) BF mainly improved the ductility of columns: through crack bridging and pull-out energy dissipation, BF increased column displacement by 33.2%. (5) The modified Eurocode 4 formula could reduce the calculation error of ultimate capacity from 6.3% to within 1%. The findings guide optimal fiber selection and dosage in practice, promoting such columns’ use in seismic and load-bearing structures. Full article

(This article belongs to the Special Issue Recent Advances in the Application of Polymer Materials in Building Construction)

22 pages, 1295 KB

Open AccessArticle

Impact of Natural and Synthetic Antioxidants on the Stability of High-Density Polyethylene

by Abdullah F. Alrashoudi, Hafizh Insan Akmaluddin, Maher M. Alrashed and Othman Y. Alothman

Polymers 2025, 17(17), 2364; https://doi.org/10.3390/polym17172364 (registering DOI) - 30 Aug 2025

Abstract

High-Density Polyethylene (HDPE) plays a crucial role in the life of every human being due to its properties such as chemical resistance, light weight, and ease of forming, among others. Its usage ranges from bottles for beverages and other liquids, to pipes, wire [...] Read more.

High-Density Polyethylene (HDPE) plays a crucial role in the life of every human being due to its properties such as chemical resistance, light weight, and ease of forming, among others. Its usage ranges from bottles for beverages and other liquids, to pipes, wire and cable insulation, and prosthetics. As it undergoes several thermal cycles during its life cycle, it is essential to maintain its qualities, even after undergoing thermal and thermo-oxidative degradation. Here, various dosages of synthetic (Irganox 1010) and natural (vitamin E) antioxidants are added to HDPE formulations to study their impacts on HDPE stability. The antioxidants are mixed physically with HDPE before the mixtures are melt-mixed three times to represent their life cycles. Samples are taken after each time and used to analyze the molecular weight distribution, rheological behavior, mechanical properties, and thermal stability. The results show that vitamin E is superior to Irganox 1010 in these tests, as vitamin E performance exceeds that of Irganox 1010, even at lower doses. The only drawback of using vitamin E is the yellow color it causes, which may necessitate the addition of another additive to enhance the color stability of HDPE in color-sensitive applications. Full article

(This article belongs to the Special Issue Biobased Polymers and Its Composites)

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22 pages, 3275 KB

Open AccessArticle

Comparative Life Cycle Assessment for the Fabrication of Polysulfone Membranes Using Slot Die Coating as a Scalable Fabrication Technique

by David Lu, Isaac Oluk, Minwoo Jung, Sophia Tseng, Diana M. Byrne, Tequila A. L. Harris and Isabel C. Escobar

Polymers 2025, 17(17), 2363; https://doi.org/10.3390/polym17172363 (registering DOI) - 30 Aug 2025

Abstract

Despite the emergence of eco-friendly solvents and scalable methods for polymeric membrane fabrication, studies on the impacts of solvent synthesis and manufacturing scale-up have not been conducted. To this end, a life cycle assessment (LCA) was developed with the goal of determining the [...] Read more.

Despite the emergence of eco-friendly solvents and scalable methods for polymeric membrane fabrication, studies on the impacts of solvent synthesis and manufacturing scale-up have not been conducted. To this end, a life cycle assessment (LCA) was developed with the goal of determining the global environmental and health impacts of producing polysulfone (PSf) membranes with the solvents PolarClean and γ-valerolactone (GVL) via doctor blade extrusion (DBE) and slot die coating (SDC). Along with PolarClean and GVL, dimethylacetamide (DMAc) and N-methyl-2-pyyrolidone (NMP) were included in the LCA as conventional solvents for comparison. The dope solution viscosity had a major influence on the material inventories; to produce a normalized membrane unit on a surface area basis, a larger quantity of PSf-PolarClean-GVL materials was required due to its high viscosity. The life cycle impact assessment found electricity and PolarClean to be major contributing parameters to multiple impact categories during membrane fabrication. The commercial synthesis route of PolarClean selected in this study required hazardous materials derived from petrochemicals, which increased its impact on membrane fabrication. Due to more materials being required to fabricate membranes via SDC to account for tool fluid priming, the PSf-PolarClean-GVL membrane fabricated via SDC exhibited the highest impacts. The amount of electricity and concentration of PolarClean were the most sensitive parameters according to Spearman’s rank coefficient analysis. A scenario analysis in which the regional energy grid was substituted found that using the Swedish grid, which comprises far more renewable technologies than the global and US energy grids, significantly lowered impacts in most categories. Despite the reported eco-friendly benefits of using PolarClean and GVL as alternatives to conventional organic solvents, the results in this study provide a wider perspective of membrane fabrication process impacts, highlighting that upstream impacts can counterbalance the beneficial properties of alternative materials. Full article

(This article belongs to the Special Issue New Studies of Polymer Surfaces and Interfaces: 2nd Edition)

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22 pages, 3518 KB

Open AccessArticle

Production and Characterisation of an Exopolysaccharide by Vreelandella titanicae Zn11_249 Isolated from Salar de Uyuni (Bolivia)

by Esteban Sabroso, José M. Martínez, Enrique Sánchez-León, Nuria Rodríguez, Ricardo Amils and Concepción Abrusci

Polymers 2025, 17(17), 2362; https://doi.org/10.3390/polym17172362 (registering DOI) - 30 Aug 2025

Abstract

The extremophilic strain Vreelandella titanicae Zn11_249 was isolated from Salar de Uyuni, an environment with high salinity, among other extreme factors. This study researched the optimised production, characterisation, antioxidant activity, and cytotoxicity of exopolysaccharides (EPS) produced by this strain under different ionic stresses. [...] Read more.

The extremophilic strain Vreelandella titanicae Zn11_249 was isolated from Salar de Uyuni, an environment with high salinity, among other extreme factors. This study researched the optimised production, characterisation, antioxidant activity, and cytotoxicity of exopolysaccharides (EPS) produced by this strain under different ionic stresses. Zn11_249 was cultured in a minimal medium with glucose as the sole carbon source as a control, and under kosmotropic (NaCl, 1 M) and chaotropic (LiCl, 0.3 M) conditions, yielding EPS_U1, EPS_U2, and EPS_U3, respectively. Maximum EPS production (336 mg/L) occurred under chaotropic conditions after 96 h. EPSs were characterised using the following techniques: Gas chromatography (GC-MS); Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR); Thermogravimetric Analysis (TGA); and Differential Scanning Calorimetry, (DSC). The results showed differences between the molecular weights for EPS_U1 (3.9 × 10⁴ Da), EPS_U2 (3.9 × 10⁴ Da), and EPS_U3 (5.85 × 10⁴ Da). Their monosaccharide molar ratios (%) were 40/25/25/10 in EPS_U1, 10/30/30/30 in EPS_U2, and 25/25/25/25 in EPS_U3, composed of mannose, galactose, rhamnose, and glucose, respectively. Functional group analysis confirmed their heteropolysaccharide nature. Thermal profiles suggest the potential of these exopolysaccharides as biomaterials. Antioxidant tests demonstrated significant activity against DPPH, OH, and O₂ radicals, while cytotoxicity assays showed no toxicity. These results highlight the biotechnological potential of EPSs from Veelandella titanicae Zn11_249 for biomedical and cosmetic uses. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Applications of Natural Polymers, 2nd Edition)

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14 pages, 8640 KB

Open AccessArticle

Effects of Poly(ethylene oxide) on the Foam Properties of Anionic Surfactants: Experiment and Molecular Dynamics Simulation

by Chaohang Xu, Ran Bi, Sijing Wang, Xiaojun Tang, Xiaolong Zhu and Guochun Li

Polymers 2025, 17(17), 2361; https://doi.org/10.3390/polym17172361 (registering DOI) - 30 Aug 2025

Abstract

Water-soluble polymers are often used as additives to adjust the foam properties of surfactant. In this study, the effects of water-soluble polymer poly(ethylene oxide) (PEO) on foam properties of two anionic surfactants, i.e., ammonium lauryl ether sulfate (ALES) and sodium dodecyl sulfate (SDS), [...] Read more.

Water-soluble polymers are often used as additives to adjust the foam properties of surfactant. In this study, the effects of water-soluble polymer poly(ethylene oxide) (PEO) on foam properties of two anionic surfactants, i.e., ammonium lauryl ether sulfate (ALES) and sodium dodecyl sulfate (SDS), were investigated by experimental and molecular dynamics simulation methods. Experimental results show that the addition of PEO can reduce the foaming ability of the two surfactants, but the inhibitory effect of PEO on the foaming ability is weakened at high surfactant concentration. Compared with ALES, PEO has a more significant inhibitory effect on the foaming ability of SDS. With the increase in PEO concentration, the half-life time of foam drainage in surfactant/water-soluble polymer composite systems gradually increases. The synergistic effect between PEO and ALES is stronger than that between PEO and SDS, resulting in a longer half-life time of foam drainage in ALES/PEO composite system. Molecular dynamics simulation results indicate that the addition of PEO can decline the air–water interface thickness of bubble films and the tail tilt angle of surfactant molecules at the air–water interface. The reduction in tail tilt angle means that the surfactant molecules are more vertical to the air–water interface and the hydrophobic interaction between adjacent tail chains of surfactants is weakened, which is unfavorable to the formation of bubble films, thus decreasing the foaming ability of surfactants. Because the ALES/PEO system has larger air–water interface thickness and surfactant tail tilt angle than the SDS/PEO system, the inhibitory effect of PEO on the foaming ability of ALES is weaker than that of SDS. Adding PEO can lower the peak position of the first hydration layer of surfactant head groups, increase the number of hydrogen bonds, and reduce the diffusion coefficient of water molecules, so that the surfactant/water-soluble polymer system has longer half-life time of foam drainage than the pure surfactant system. Due to the synergistic effect between ALES and PEO, the ALES/PEO system has a higher peak value of the first hydration layer of surfactant head groups, more hydrogen bonds, and lower diffusion coefficient of water molecules than the SDS/PEO system. Therefore, the half-life time of foam drainage in the ALES/PEO system is longer than that in the SDS/PEO system. Full article

(This article belongs to the Special Issue Aqueous Foam of Surfactant–Polymer Composites: Properties and Applications)

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30 pages, 1605 KB

Open AccessArticle

Investigation of the Melt-Rotation Effects on Fiber Orientation Variation and Geometrical Shrinkage in FRP Injection-Molded Parts

by Jing-Kai Gao, Fang-Lin Hsieh, Min-Yuan Chien and Chao-Tsai Huang

Polymers 2025, 17(17), 2360; https://doi.org/10.3390/polym17172360 (registering DOI) - 30 Aug 2025

Abstract

The study focuses on the asymmetric shrinkage typically occurring between the upstream and downstream regions of FRP injection-molded products, a challenge that is particularly difficult to manage and improve. Specifically, two sets of four-cavity systems in one mold were utilized as the experimental [...] Read more.

The study focuses on the asymmetric shrinkage typically occurring between the upstream and downstream regions of FRP injection-molded products, a challenge that is particularly difficult to manage and improve. Specifically, two sets of four-cavity systems in one mold were utilized as the experimental platform. One set used a balanced runner (BR) system, and the other used a non-balanced runner (NBR) system. Each cavity in the four-cavity systems contained an ASTM D638 standard specimen with dimensions of 63.5 mm × 9.53 mm × 3.5 mm. Both CAE simulation and experimental methods were applied. The results show that the filling patterns from the simulation analysis closely matched those from the experimental study for both BR and NBR systems. Furthermore, by comparing the geometric shrinkage of the injected parts, significant differences were observed in the dimensional deformation in three directions (x, y, and z) between the NBR and BR systems. Specifically, at the end of the filling region (EFR), there was no noticeable difference in shrinkage along the flow direction, but the shrinkage in the cross-flow and thickness directions was reduced in the NBR system. Additionally, for the same cavity (1C) in both BR and NBR systems, the melt-rotation effect significantly reduced shrinkage in both the cross-flow and thickness directions. These findings strongly suggest that melt rotation can effectively modify the dimensional shrinkage of injection-molded parts. Moreover, fiber orientation analyses of the 1C cavity were also performed using CAE simulation for both BR and NBR systems. The results show that in the NBR system, the melt-rotation effect substantially alters the fiber orientation. Specifically, the fiber orientation tensors in the cross-flow (A₂₂) direction exhibit a decreasing trend. It can be speculated that the melt rotation alters the flow field, which subsequently changes the fiber orientation by reducing the flow-fiber coupling effect, thereby reducing the upstream-to-downstream asymmetry in the cross-flow direction. Through in-depth analysis, it is demonstrated that the correlation between the macroscopic geometric shrinkage and the microscopic fiber orientation changes is highly consistent. Specifically, in the EFR, ΔA₂₂ decreased by 0.0376, improving upstream/downstream shrinkage asymmetry in the cross-flow direction (Ly). Future work will investigate alternative melt-rotation designs and the optimization of model-internal parameters in FOD prediction. Full article

(This article belongs to the Special Issue Advances in Polymer Processing Technologies: Injection Molding)

17 pages, 1763 KB

Open AccessArticle

Discovery and Development of One Monomer Molecularly Imprinted Polymers (OMNiMIPs)

by Danielle S. Meador, Stephanie S. Houck and David A. Spivak

Polymers 2025, 17(17), 2359; https://doi.org/10.3390/polym17172359 (registering DOI) - 30 Aug 2025

Abstract

Molecularly imprinted polymers (MIPs) are polymeric receptors for a targeted template molecule that are traditionally formed using a combination of functional monomers and crosslinkers. While investigating novel crosslinkers for MIPs, one of these (2-(methacryloylamino)ethyl-2-methylacrylate (referred to as N,O-bismethacryloyl ethanolamine or “NOBE”)) performed better [...] Read more.

Molecularly imprinted polymers (MIPs) are polymeric receptors for a targeted template molecule that are traditionally formed using a combination of functional monomers and crosslinkers. While investigating novel crosslinkers for MIPs, one of these (2-(methacryloylamino)ethyl-2-methylacrylate (referred to as N,O-bismethacryloyl ethanolamine or “NOBE”)) performed better when used alone versus in combination with other monomers. This introduced the concept of one monomer molecularly imprinted polymers, given the acronym OMNiMIPs, and prompted studies provided in this report that clarify OMNiMIPs have fundamental differences compared to traditionally formulated MIPs. Enantioselectivity studies using BOC-L-tyrosine as a standard template showed that NOBE OMNiMIPs afforded higher-performing MIPs compared with traditional MIPs, have significantly higher binding capacities, and have an internal hydrogen-bonded crosslinking structure that contributes to the morphological stability of the binding site structure. Based on the adventitious discovery of NOBE OMNiMIPs, new analogs based on the NOBE structure were developed and evaluated for further enhancement of molecular recognition performance and novel capabilities of OMNiMIPs. While the majority of the new OMNiMIPs exhibited enantiomeric selectivity toward BOC-L-tyr, improvements were not observed compared with NOBE. Full article

(This article belongs to the Special Issue New Advances in Molecularly Imprinted Polymer)

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20 pages, 3801 KB

Open AccessArticle

Structural Study of Metakaolin-Phosphate Geopolymers Prepared with Wide Range of Al/P Molar Ratios

by Martin Keppert, Martina Urbanová, Ivana Šeděnková, Václav Pokorný, Michala Breníková, Jitka Krejsová, Vojtěch Pommer, Eva Vejmelková, Dana Koňáková and Jiří Brus

Polymers 2025, 17(17), 2358; https://doi.org/10.3390/polym17172358 (registering DOI) - 30 Aug 2025

Abstract

Geopolymers represent an innovative and environmentally sustainable alternative to traditional construction materials, offering significant potential for reducing anthropogenic CO₂ emissions. Among these, phosphoric acid-activated metakaolin-based systems have attracted increasing attention for their chemical and thermal resilience. In this study, we present a [...] Read more.

Geopolymers represent an innovative and environmentally sustainable alternative to traditional construction materials, offering significant potential for reducing anthropogenic CO₂ emissions. Among these, phosphoric acid-activated metakaolin-based systems have attracted increasing attention for their chemical and thermal resilience. In this study, we present a comprehensive structural and mechanical evaluation of metakaolin-based geopolymers synthesized across a wide range of Al/P molar ratios (0.8–4.0). Six formulations were systematically prepared and analyzed using X-ray powder diffraction (XRPD), small-angle X-ray scattering (SAXS), Fourier-transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (ssNMR), and complementary mechanical testing. The novelty of this work lies in the integrated mapping of composition–structure–property relationships across the broad Al/P spectrum under controlled synthesis, combined with the rare application of SAXS to reveal composition-dependent nanoscale domains (~18–50 nm). We identify a stoichiometric window at Al/P ≈ 1.5, where complete acid consumption leads to a structurally homogeneous AlVI–O–P network, yielding the highest compressive strength. In contrast, acid-rich systems exhibit divergent flexural and compressive behaviors, with enhanced flexural strength linked to hydrated silica domains arising from metakaolin dealumination, quantitatively tracked by ²⁹Si MAS NMR. XRPD further reveals the formation of uncommon Si–P crystalline phases (SiP₂O₇, Si₅P₆O₂₅) under low-temperature curing in acid-rich compositions. Together, these findings provide new insights into the nanoscale structuring, phase evolution, and stoichiometric control of silica–alumino–phosphate geopolymers, highlighting strategies for optimizing their performance in demanding thermal and chemical environments. Full article

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

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16 pages, 3063 KB

Open AccessArticle

BA-CD Composite Polymers for Efficient Adsorption of Diverse Dyes and Its Mechanism: A Discussion-Based Thermal Dynamic and Kinetic Study

by Zhaona Liu, Make Li, Yangyang Zheng and Huacheng Zhang

Polymers 2025, 17(17), 2357; https://doi.org/10.3390/polym17172357 - 29 Aug 2025

Abstract

Boric acid/β-CD-based polymers (BA-CD) possess hierarchical porous structures and efficient functional groups for further molecular recognition, which are used for the adsorption of a series of cationic and anionic organic dyes. The effects of pH, contact time, initial concentration of solution, and temperature [...] Read more.

Boric acid/β-CD-based polymers (BA-CD) possess hierarchical porous structures and efficient functional groups for further molecular recognition, which are used for the adsorption of a series of cationic and anionic organic dyes. The effects of pH, contact time, initial concentration of solution, and temperature on the adsorption performance were experimentally investigated in detail. Surprisingly, the adsorption capacities of BA-CD towards RB exhibited a higher value of 733.2 mg g⁻¹ among a series of cationic and anionic dyes. The adsorption kinetics further indicated that the adsorption of dyes by BA-CD belonged to a quasi-second-order kinetic model, while the adsorption isotherms demonstrated the adsorption process as the Langmuir isotherm model. The characterization of the adsorption process was performed in the presence of monomolecular layer chemisorption. In addition, the reusability test showed that BA-CD had a high reusability rate of 90% in MG after five cycles, indicating its future potential for the treatment of dye wastewater. Full article

(This article belongs to the Section Polymer Chemistry)

14 pages, 2161 KB

Open AccessArticle

Sustainable Valorization of Plastic Waste and Palm Fronds into Chemically Activated Carbon–Polymer Composite

by Junaid Saleem, Zubair Khalid Baig Moghal, Furqan Tahir and Gordon McKay

Polymers 2025, 17(17), 2356; https://doi.org/10.3390/polym17172356 - 29 Aug 2025

Abstract

Polyolefin waste is an abundant yet underutilized resource for developing value-added materials, while palm fronds (PF), a lignocellulosic biomass, offer a promising feedstock for activated carbon (AC) production. However, conventional AC from biomass is typically obtained in powdered form, making it difficult to [...] Read more.

Polyolefin waste is an abundant yet underutilized resource for developing value-added materials, while palm fronds (PF), a lignocellulosic biomass, offer a promising feedstock for activated carbon (AC) production. However, conventional AC from biomass is typically obtained in powdered form, making it difficult to handle and recover in aqueous systems without external support. Incorporating polyolefins during synthesis enables the formation of chemically activated polymer–carbon composite (PCC), which offers improved usability and recovery. This study aims to evaluate the environmental sustainability of producing PCC from PF and polyolefins, using Life Cycle Assessment (LCA) to quantify energy consumption and climate change impact. The LCA results show a net energy demand of 88.59 MJ and a climate change impact of 3.57 kg CO₂ eq. per kg of PCC. Substituting conventional petroleum-based AC with PCC led to a 28% reduction in climate change impact and a 30% decrease in energy demand. By integrating biomass and plastic waste, this research supports sustainable material development and promotes circular economy practices in water treatment applications. Full article

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

15 pages, 1474 KB

Open AccessArticle

Multiscale Structural Engineering of Cellulose Foams: Performance Characterization and Fiber Imaging

by Patricija Pevec, Urška Kavčič, Aleš Hladnik and Diana Gregor-Svetec

Polymers 2025, 17(17), 2355; https://doi.org/10.3390/polym17172355 - 29 Aug 2025

Abstract

The paper industry is always looking for possible solutions for new fiber-based products, such as protective and cushioning materials. These materials must be carefully designed to provide effective cushioning while also being lightweight to reduce transportation costs. Additionally, they need to offer protection [...] Read more.

The paper industry is always looking for possible solutions for new fiber-based products, such as protective and cushioning materials. These materials must be carefully designed to provide effective cushioning while also being lightweight to reduce transportation costs. Additionally, they need to offer protection from environmental and mechanical damage, besides having good processability to ensure proper buffering. The widely used protective and cushioning materials, such as plastic foams and expanded or extruded polystyrene, create significant disposal challenges. Therefore, there is increasing demand for biodegradable and sustainable materials for cushioning applications. The focus of our research was to develop fiber-based foams and investigate the influence of different compositions (hardwood and softwood) of cellulose fibers on the basic (mass, thickness, density) and mechanical properties (three-point bend test, tensile properties). Foams made entirely from short eucalyptus fibers (100S) exhibited the highest density (28.0 ± 0.34 kg/m³) and lowest thickness (38.82 ± 4.21 mm), resulting in superior tensile strength and elastic modulus but lower strain at break. In contrast, foams composed of long spruce fibers (100L) had the lowest density (19.0 ± 0.27 kg/m³) and highest thickness (58.52 ± 1.50 mm), with lower strength and stiffness but much higher ductility and porosity (confirmed by ~30% higher air permeability compared to 100S). Blended formulations demonstrated intermediate behavior, with the 50S50L foam showing a favorable balance of strength, stiffness, and flexibility. Visual analysis confirmed heterogeneous fiber distribution with localized agglomerates and compaction at the bottom layer due to casting. To further interpret the complex relationships within the dataset and uncover patterns, Principal Component Analysis (PCA) was applied to all experimental results. The findings of the research contribute to the broader understanding of how different fiber types and blends impact the performance of sustainable cellulose-based foams, with potential implications for the development of biodegradable packaging and lightweight construction materials. Full article

(This article belongs to the Special Issue Advances in the Preparation, Properties and Application of Polyurethane, Cellulose and Their Composites (3rd Edition))

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