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Polymers
Volume 17
Issue 10
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Polymers, Volume 17, Issue 10 (May-2 2025) – 135 articles

Cover Story (view full-size image): Polyhydroxyalkanoates (PHAs) are biodegradable bioplastics that have attracted considerable attention as sustainable alternatives to conventional petroleum-based plastics. Nevertheless, their practical applications are limited due to their inherently poor mechanical properties. To address this limitation, we synthesized crosslinked particles of amorphous poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) to serve as biodegradable impact modifiers. In the present study, the effects of incorporating either crosslinked or uncrosslinked amorphous PHBH on the mechanical properties of crystalline PHBH were investigated through comprehensive structural characterization. View this paper
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22 pages, 8597 KiB  
Article
Mitigation of Membrane Fouling in Lignin Recovery from Black Liquor via Surface-Patterned Ceramic Membrane
by Weikang Wang, Ning Kuang, Wenjie Zhao and Qingdang Li
Polymers 2025, 17(10), 1424; https://doi.org/10.3390/polym17101424 - 21 May 2025
Viewed by 121
Abstract
Among the various methods for recovering lignin from black liquor, membrane separation has gained prominence in the paper industry due to its advantages of uniform molecular weight distribution, high recovery rates, and absence of secondary pollution. However, over time, lignin particles tend to [...] Read more.
Among the various methods for recovering lignin from black liquor, membrane separation has gained prominence in the paper industry due to its advantages of uniform molecular weight distribution, high recovery rates, and absence of secondary pollution. However, over time, lignin particles tend to deposit and form a cake layer on the membrane surface, leading to membrane fouling and a decline in filtration flux. To address this issue, this study investigates the construction of ceramic membranes with radial rib patterns, and examines the effects of different trans-membrane pressure differences and radial rib patterns on membrane surface shear force and particle deposition. The research findings indicate that at a trans-membrane pressure difference of 0.5 bar and a blade rotation speed of 1000 r/min, the membrane surface experiences the highest shear force. Compared with those without patterns, ceramic membranes with radial rib patterns can more effectively delay the deposition of particles. Furthermore, it was observed that ceramic membranes combining coarse and fine rib patterns exhibit a more pronounced increase in membrane surface shear force. Full article
(This article belongs to the Special Issue Lignin Isolation, Characterization and Application)
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23 pages, 8611 KiB  
Article
Tailoring CuO/Polyaniline Nanocomposites for Optoelectronic Applications: Synthesis, Characterization, and Performance Analysis
by Fedda Alzoubi, Mahmoud Al-Gharram, Tariq AlZoubi, Hasan Al-Khateeb, Mohammed Al-Qadi, Osamah Abu Noqta, Ghaseb Makhadmeh, Omar Mouhtady, Mohannad Al-Hmoud and Jestin Mandumpal
Polymers 2025, 17(10), 1423; https://doi.org/10.3390/polym17101423 - 21 May 2025
Viewed by 125
Abstract
This research focuses on creating CuO/PANI nanocomposite films by electrodepositing copper oxide nanoparticles into a polyaniline matrix on ITO substrates. The CuO nanoparticle content was adjusted between 7% and 21%. These nanocomposites are promising for various applications, such as optoelectronic devices, gas sensors, [...] Read more.
This research focuses on creating CuO/PANI nanocomposite films by electrodepositing copper oxide nanoparticles into a polyaniline matrix on ITO substrates. The CuO nanoparticle content was adjusted between 7% and 21%. These nanocomposites are promising for various applications, such as optoelectronic devices, gas sensors, electromagnetic interference shielding, and electrochromic devices. We utilized UV-Vis spectroscopy to examine the nanocomposites’ interaction with light, allowing us to ascertain their refractive indices and absorption coefficients. The Scherrer formula facilitated the determination of the average crystallite size, shedding light on the material’s internal structure. Tauc plots indicated a reduction in the energy-band gap from 3.36 eV to 3.12 eV as the concentration of CuO nanoparticles within the PANI matrix increased, accompanied by a rise in electrical conductivity. The incorporation of CuO nanoparticles into the polyaniline matrix appears to enhance the conjugation length of PANI chains, as evidenced by shifts in the quinoid and benzenoid ring vibrations in FTIR spectra. SEM analysis indicates that the nanocomposite films possess a relatively smooth and homogeneous surface. Additionally, FTIR and XRD analyses demonstrate an increasing degree of interaction between CuO nanoparticles and PANI chains with higher CuO concentrations. At lower concentrations, interactions were minimal. In contrast, at higher concentrations, more significant interactions were observed, which facilitated the stretching of polymer chains, improved molecular packing, and facilitated the formation of larger crystalline structures within the PANI matrix. The incorporation of CuO nanoparticles resulted in nanocomposites with electrical conductivities ranging from 1.2 to 17.0 S cm−1, which are favorable for optimum performance in optoelectronic devices. These results confirm that the nanocomposite films combine pronounced crystallinity, markedly enhanced electrical conductivity, and tunable band-gap energies, positioning them as versatile candidates for next-generation optoelectronic devices. Full article
(This article belongs to the Section Polymer Analysis and Characterization)
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22 pages, 7333 KiB  
Article
Multi-Objective Toughness Optimization of Epoxy Resin for Steel Bridge Deck Pavement Based on Crosslink Density Regulation
by Yixin Zhou, Gang Xu, Yulou Fan, Yuxiang Li, Xianhua Chen, Jun Yang and Wei Huang
Polymers 2025, 17(10), 1422; https://doi.org/10.3390/polym17101422 - 21 May 2025
Viewed by 99
Abstract
Epoxy resins (ERs) are esteemed for their mechanical robustness and adhesive qualities, particularly in steel bridge deck applications. Nonetheless, their intrinsic brittleness limits broader utility. This study addresses this limitation by modulating ER crosslink density through adjustments in curing agent concentration, incorporation of [...] Read more.
Epoxy resins (ERs) are esteemed for their mechanical robustness and adhesive qualities, particularly in steel bridge deck applications. Nonetheless, their intrinsic brittleness limits broader utility. This study addresses this limitation by modulating ER crosslink density through adjustments in curing agent concentration, incorporation of hyperbranched polymers (HBPs), and optimization of curing conditions. Employing a multi-objective optimization strategy, this research aims to enhance toughness while minimizing strength degradation. Non-isothermal curing kinetics, realized using the differential scanning calorimetry (DSC) method, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), tensile testing, and thermogravimetric analysis (TGA), were employed to investigate the effects of curing agent and HBP content on the curing reaction, mechanical properties, and thermal stability, respectively. Response surface methodology facilitated comprehensive optimization. Findings indicate that both curing agent and HBP contents significantly influence curing dynamics and mechanical performance. Curing agent content below 40% or above 50% can induce side reactions, adversely affecting properties. While a curing agent content exceeding 45% or an HBP content exceeding 5% improves the toughness of ER, these increases concurrently reduce mechanical strength and thermal stability. The study identifies an optimal formulation comprising 45.21% curing agent, a curing temperature of 60.45 °C, and 5.77% HBP content. Full article
(This article belongs to the Special Issue Epoxy Resins and Epoxy-Based Composites: Research and Development)
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16 pages, 5718 KiB  
Article
Simulation Analysis and Optimization Design of Dome Structure in Filament Wound Composite Shells
by Yuan Zhou, Yuyang Zou, Qingguo Xia, Longkai Cao, Minghua Zhang, Tao Shen and Jianke Du
Polymers 2025, 17(10), 1421; https://doi.org/10.3390/polym17101421 - 21 May 2025
Viewed by 103
Abstract
Carbon fiber-reinforced composites are widely used in the aerospace industry due to their exceptional mechanical properties. However, the dome region of composite pressure vessels is prone to stress concentrations under internal pressure, often resulting in premature failure and reduced burst strength. This study [...] Read more.
Carbon fiber-reinforced composites are widely used in the aerospace industry due to their exceptional mechanical properties. However, the dome region of composite pressure vessels is prone to stress concentrations under internal pressure, often resulting in premature failure and reduced burst strength. This study developed a finite element model of a reinforced dome structure, which showed excellent agreement with hydrostatic test results, with less than 5.9% deviation in strain measurements. To optimize key reinforcement parameters, a high-accuracy surrogate model based on a backpropagation neural network was integrated with a multi-objective genetic algorithm. The results indicate that compared to the unreinforced dome, the optimized structure reduced the maximum fiber-aligned stress in the dome region by 6.8%; moreover, it achieved a 9.3% reduction in overall mass compared to the unoptimized reinforced configuration. These findings contribute to the structural optimization of composite pressure vessel domes. Full article
(This article belongs to the Section Polymer Composites and Nanocomposites)
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15 pages, 2591 KiB  
Article
Empirical Modeling of Seasonal Cooling Performance Based on Test Devices Using Zinc Oxide/Low-Density Polyethylene Passive Cooling Membranes
by Yinjia Zhang, Jun Natsuki, Chengwu Weng, Vuong Dinh Trung, Yiwen Wang, Lina Cui and Toshiaki Natsuki
Polymers 2025, 17(10), 1420; https://doi.org/10.3390/polym17101420 - 21 May 2025
Viewed by 98
Abstract
Outdoor structures, such as vehicles, buildings, and outdoor equipment, are prone to overheat due to prolonged exposure to solar irradiation, which could affect their service life or user experience. To address this urgent issue, we developed a climate-adaptive thermal management solution using zinc [...] Read more.
Outdoor structures, such as vehicles, buildings, and outdoor equipment, are prone to overheat due to prolonged exposure to solar irradiation, which could affect their service life or user experience. To address this urgent issue, we developed a climate-adaptive thermal management solution using zinc oxide (ZnO)/low-density polyethylene (LDPE) hybrid membranes. The cooling performance of the membrane was examined across different seasons, achieving maximum temperature reductions (∆T) of 12.55 °C in summer, 8.02 °C in autumn, and 2.90 °C in winter. Our results demonstrated that the material’s cooling efficiency varied with seasonal solar irradiance, showing quicker responsiveness in summer and reduced in winter, effectively preventing overcooling. Moreover, the enclosed specific volume (SV) was identified as another critical parameter affecting cooling performance. We established an empirical correlation between ∆T and SV to quantify passive cooling performance across different seasons. This standardized method for assessing the cooling effect enables comparison between different materials, which is essential for determining climate-adaptive thermal management. Notably, the ZnO/LDPE membranes exhibited stable and balanced performance year-round, highlighting their potential for substantial energy savings in outdoor applications. This research provided valuable insights for designing climate-adaptive passive cooling materials that optimize thermal management across seasonal variations while contributing to sustainable energy conservation. Full article
(This article belongs to the Section Polymer Membranes and Films)
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13 pages, 1887 KiB  
Article
Polymer-Based Thermal Protective Composites: The Role of Reinforcement and Matrix in Providing Strength and Fire Resistance
by Mohammed Meiirbekov, Assem Kuandyk, Mukhammed Sadykov, Meiir Nurzhanov, Nurmakhan Yesbolov, Berdiyar Baiserikov, Ilyas Ablakatov, Laura Mustafa, Botagoz Medyanova, Arman Kulbekov, Sunkar Orazbek and Abussaid Yermekov
Polymers 2025, 17(10), 1419; https://doi.org/10.3390/polym17101419 - 21 May 2025
Viewed by 111
Abstract
This study addresses the need for thermomechanically robust materials for high-temperature environments by investigating fabric-reinforced composites produced through polymer infiltration and thermal pressing using phenol-formaldehyde (PF) and epoxy (ER) resins. Experimental validation was required due to the lack of comparative data across different [...] Read more.
This study addresses the need for thermomechanically robust materials for high-temperature environments by investigating fabric-reinforced composites produced through polymer infiltration and thermal pressing using phenol-formaldehyde (PF) and epoxy (ER) resins. Experimental validation was required due to the lack of comparative data across different textile reinforcements under identical conditions. Seven technical fabrics—carbon, aramid, basalt, silica, fiberglass, asbestos, and a carbon/aramid hybrid—were used as reinforcements. Mechanical testing revealed that carbon- and hybrid fiber composites exhibited the highest tensile (up to 465 MPa) and compressive strengths (up to 301 MPa), particularly when combined with ER. Conversely, the use of PF generally resulted in a 30–50% reduction in mechanical strength. However, PF-based composites demonstrated superior thermal resistance, with the silica/PF combination showing the lowest back-face temperature (401 °C), up to 37% lower than other pairings. Thermal conductivity ranged from 0.041 to 0.51 W/m·K, with PF-based systems offering 6–12% lower values on average compared to ER-based analogs. Morphological analysis confirmed better interfacial bonding in ER composites, while PF systems showed higher structural integrity under thermal loading. Overall, the results emphasize the trade-offs between mechanical strength and thermal protection depending on the fabric–resin combination. Among all variants, the silica fabric with PF demonstrated the most balanced performance, making it a promising candidate for thermomechanical applications. Full article
(This article belongs to the Section Polymer Composites and Nanocomposites)
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19 pages, 6754 KiB  
Article
New Challenges in Assessment of the Acoustic Properties of Coating Polymers
by Mariana Domnica Stanciu, Maria Violeta Guiman and Silviu Marian Năstac
Polymers 2025, 17(10), 1418; https://doi.org/10.3390/polym17101418 - 21 May 2025
Viewed by 79
Abstract
The study presented in this paper investigates the influence of coating polymers on the acoustic properties of resonant spruce wood. It evaluates absorption, acoustic reflection, and resonance frequency spectrum characteristics in both unvarnished and varnished samples, with the interface between the coating polymer [...] Read more.
The study presented in this paper investigates the influence of coating polymers on the acoustic properties of resonant spruce wood. It evaluates absorption, acoustic reflection, and resonance frequency spectrum characteristics in both unvarnished and varnished samples, with the interface between the coating polymer and the wood modifying the acoustic response. The novelty of the research consists in evaluating the acoustic and dynamic parameters of resonant spruce wood boards, varnished with varnishes with different chemical properties (oil-based varnish, spirit varnish, nitrocellulose varnish). The study focuses on the influence of the type of varnish and the thickness of the varnish film on the frequency spectrum, damping coefficient, quality factor, acoustic absorption coefficient, and sound reflection. The sound absorption coefficient increases with the number of varnish layers and is influenced by the sound’s frequency range, the type of varnish, and the quality of the wood—factors that collectively enhance acoustic performance. For instance, oil-based varnish applied in 5 or 10 layers contributes to a fuller sound at a frequency of 1.5 kHz. In contrast, spirit varnish, which has a lower acoustic absorption coefficient at this frequency, and a reduced damping coefficient, can lead to a nasal tone, although the frequency spectrum turns out to have the richest. Applying more than 10 layers of varnish softens the sound when using oil-based varnish but sharpens it with spirit varnish on resonant wood. Thus, the acoustic performance of a soundboard can be tailored by selecting the appropriate varnishing system and number of layers applied. However, a detailed analysis of the timbre of musical instruments finished with these varnishes is necessary to confirm their influence on the acoustic quality of the instruments. Full article
(This article belongs to the Special Issue Advances in Wood and Wood Polymer Composites)
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14 pages, 938 KiB  
Article
Gun–Bullet Model-Based Noncovalent Interactions Boosting Visible Light Photocatalytic Hydrogen Production in Poly Thieno[3,2-b]Thiophene/Graphitic Carbon Nitride Heterojunctions
by Yong Li, Jialu Tong, Zihao Chai, Yuanyuan Wu, Dongting Wang and Hongbin Li
Polymers 2025, 17(10), 1417; https://doi.org/10.3390/polym17101417 - 21 May 2025
Viewed by 66
Abstract
Linear conjugated polymer photocatalysts are still hampered by challenges involving low charge separation efficiency and poor water dispersibility, which are crucial factors during the photocatalytic water splitting process. Herein, we synthesized Poly thieno[3,2-b]thiophene (PTT) nanoparticles with excellent visible light response characteristic. Subsequently, we [...] Read more.
Linear conjugated polymer photocatalysts are still hampered by challenges involving low charge separation efficiency and poor water dispersibility, which are crucial factors during the photocatalytic water splitting process. Herein, we synthesized Poly thieno[3,2-b]thiophene (PTT) nanoparticles with excellent visible light response characteristic. Subsequently, we constructed the gun–bullet model PTT/graphitic carbon nitride (PTT/g-C3N4) heterojunctions for photocatalytic hydrogen production, where PTT with good visible light response characteristic serves as the bullets and g-C3N4 with good water dispersibility serves as the guns. The as-prepared PTT/g-C3N4 heterojunctions show greatly accelerated charge separation and excellent photocatalytic hydrogen production performance. Specifically, 10PTT/g-C3N4 demonstrates extraordinary hydrogen production performance, reaching 6.56 mmol g−1 h−1 (2 wt% Pt loading, 0.1 M AA as sacrificial agent, λ > 420 nm), calculated to be 15.3 and 22.6 times those of PTT and g-C3N4, respectively. Mechanistic studies reveal that the significantly improved performance of PTT/g-C3N4 heterojunctions is ascribed to the accelerated charge transfer, which originates from the C…S/N…S noncovalent interactions among PTT and g-C3N4. The C…S/N…S noncovalent interactions act as an efficient interface charge transmission channel (ICTC), accelerating the steady stream of excited electron transfer from the lowest unoccupied molecular orbital (LUMO) of PTT to that of g-C3N4. The gun–bullet model heterojunctions proposed here provide a practical strategy for achieving exceptional visible light photocatalytic hydrogen production by combining charge separation with water dispersibility in polymer/polymer heterojunctions via noncovalent interactions. Full article
(This article belongs to the Section Polymer Applications)
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49 pages, 7115 KiB  
Review
Emerging Trends in Silane-Modified Nanomaterial–Polymer Nanocomposites for Energy Harvesting Applications
by Vadakkaveedu Subramanian Niranjana, Sathiyanathan Ponnan, Arvind Mukundan, Arun Anand Prabu and Hsiang-Chen Wang
Polymers 2025, 17(10), 1416; https://doi.org/10.3390/polym17101416 - 21 May 2025
Viewed by 192
Abstract
Nanomaterials (NMs) have gained tremendous attention in various applications in the modern era. The most significant challenge associated with NMs is their strong propensity to aggregate. The chemical surface modification of NMs has garnered notable attention in managing NM dispersion and aggregation. Among [...] Read more.
Nanomaterials (NMs) have gained tremendous attention in various applications in the modern era. The most significant challenge associated with NMs is their strong propensity to aggregate. The chemical surface modification of NMs has garnered notable attention in managing NM dispersion and aggregation. Among the modification approaches, the silane modification of NMs has generated great interest among researchers as a versatile approach to tailoring the surface characteristics of NMs. This review comprehensively examined the recent advancements in silane modification techniques with a focus on triboelectric nanogenerator (TENG) applications. It provides an overview of silane chemistry and its interaction with diverse NMs, elucidating the underlying mechanisms governing the successful surface functionalization process. This review emphasized the silane modification, such as improved mechanical properties of composites, enhanced electrical and thermal conductivity, functional coatings, water treatment, textile industries, catalysis, membrane applications, and biomedical applications, of various NMs. In particular, the role of silane-modified NMs in advancing energy harvesting technologies was highlighted, showcasing their potential to enhance the performance and stability of next-generation devices. Full article
(This article belongs to the Special Issue Advances in Polymer Composites for Nanogenerator Applications)
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25 pages, 899 KiB  
Review
A Scoping Review of Vitamins Detection Using Electrochemically Polymerised, Molecularly Imprinted Polymers
by Mohd Azerulazree Jamilan, Balqis Kamarudin, Zainiharyati Mohd Zain, Kavirajaa Pandian Sambasevam, Faizatul Shimal Mehamod and Mohd Fairulnizal Md Noh
Polymers 2025, 17(10), 1415; https://doi.org/10.3390/polym17101415 - 21 May 2025
Viewed by 106
Abstract
Vitamins are crucial micro-nutrients for overall well-being, making continuous monitoring essential. There are demands to provide an alternative detection, especially using a portable detection or a point-of-care-testing (POCT) device. One promising approach is employing an in situ electro-polymerised MIP (eMIP), which offers a [...] Read more.
Vitamins are crucial micro-nutrients for overall well-being, making continuous monitoring essential. There are demands to provide an alternative detection, especially using a portable detection or a point-of-care-testing (POCT) device. One promising approach is employing an in situ electro-polymerised MIP (eMIP), which offers a straightforward polymerisation technique on screen-printed electrodes (SPEs). Here, we report a review based on three databases (PubMed, Scopus, and Web of Science) from 2014 to 2024 using medical subject heading (MeSH) terms “electrochemical polymerisation” OR “electropolymerisation” crossed with the terms “molecularly imprinted polymer” AND “vitamin A” OR “vitamin D” OR “vitamin E” OR “vitamin K” OR “fat soluble vitamin” OR “vitamin B” OR “vitamin C” OR “water soluble vitamin”. The resulting 12 articles covered the detection of vitamins in ascorbic acid, riboflavin, cholecalciferol, calcifediol, and menadione using monomers of catechol (CAT), 3,4-ethylenedioxythiophene (EDOT), o-aminophenol (oAP), o-phenylenediamine (oPD), pyrrole, p-aminophenol (pAP), p-phenylenediamine (pPD), or resorcinol (RES), using common bare electrodes including graphite rod electrode (GRE), glassy carbon electrode (GCE), gold electrode (GE), and screen-printed carbon electrode (SPCE). The most common electrochemical detections were differential pulse voltammetry (DPV) and linear sweep voltammetry (LSV). The imprinting factor (IF) of the eMIP-modified electrodes were from 1.6 to 21.0, whereas the cross-reactivity was from 0.0% to 29.9%. Several types of food and biological samples were tested, such as supplement tablets, poultry and pharmaceutical drugs, soft drinks, beverages, milk, infant formula, human and calf serum, and human plasma. However, more discoveries and development of detection methods needs to be performed, especially for the vitamins that have not been studied yet. This will allow the improvement in the application of eMIPs on portable-based detection and POCT devices. Full article
(This article belongs to the Special Issue Molecularly Imprinted Polymers: Latest Advances and Applications)
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13 pages, 1146 KiB  
Article
Interpolymer Complexation Between Cellulose Ethers, Poloxamers, and Polyacrylic Acid: Surface-Dependent Behavior
by Eldar Kopishev, Fatima Jafarova, Lyazat Tolymbekova, Gaini Seitenova and Ruslan Sаfarov
Polymers 2025, 17(10), 1414; https://doi.org/10.3390/polym17101414 - 21 May 2025
Viewed by 98
Abstract
This study examines the surface-dependent formation of interpolymer complexes (IPCs) by the layer-by-layer (LBL) deposition method. The materials used in this analysis are poly(acrylic acid) (PAA) combined with cellulose ethers, namely methyl cellulose (MC), hydroxypropyl cellulose (HPC), and hydroxyethyl cellulose (HEC), and poloxamers [...] Read more.
This study examines the surface-dependent formation of interpolymer complexes (IPCs) by the layer-by-layer (LBL) deposition method. The materials used in this analysis are poly(acrylic acid) (PAA) combined with cellulose ethers, namely methyl cellulose (MC), hydroxypropyl cellulose (HPC), and hydroxyethyl cellulose (HEC), and poloxamers PX188 and PX407. PMMA, PS, and glass surfaces have been used to study the influence of hydrophobicity and hydrophilicity on IPC growth and its properties. Through contact angle measurements, PMMA and PS were found to be hydrophobic and glass hydrophilic. It was revealed by gravimetric analysis that IPC films reveal the highest growth on PMMA substrates, followed by PS and glass. Both the molecular weight of HEC and the hydrophobicity of the surface considerably affected the growth. Hydrogen-bonded complexation was evident by means of FTIR spectroscopy, while changes in some characteristic absorption bands demonstrated the extent of interactions between polymers. Scanning electron microscopy showed that variations in the microstructure of surfaces occur; PAA-MC and poloxamer complex layers were well organized on hydrophobic substrates. Thus, the experimental results showed surface properties, especially hydrophobicity, to be important for IPC growth and structure. These findings contribute to the understanding of IPC behavior on different substrates, thus giving insights into applications in drug delivery, coatings, and functional films. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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14 pages, 2976 KiB  
Article
Chromium-Doped Biomass-Based Hydrochar-Catalyzed Synthesis of 5-Hydroxymethylfurfural from Glucose
by Huimin Gao, Wei Mao, Pize Xiao, Chutong Ling, Zhiming Wu and Jinghong Zhou
Polymers 2025, 17(10), 1413; https://doi.org/10.3390/polym17101413 - 20 May 2025
Viewed by 124
Abstract
5-Hydroxymethylfurfural (HMF) is a versatile carbohydrate-derived platform chemical that has been used for the synthesis of a number of commercially valuable compounds. In this study, several chromium (Cr)-doped, biomass-derived hydrochar catalysts were synthesized via the one-pot method using starch, eucalyptus wood, and bagasse [...] Read more.
5-Hydroxymethylfurfural (HMF) is a versatile carbohydrate-derived platform chemical that has been used for the synthesis of a number of commercially valuable compounds. In this study, several chromium (Cr)-doped, biomass-derived hydrochar catalysts were synthesized via the one-pot method using starch, eucalyptus wood, and bagasse as carbon sources. Then, the performance of these synthesized materials for the catalytic conversion of glucose into HMF was evaluated by, primarily, the yield of HMF. The synergistic interactions between the Cr salt and the different biomass components were investigated, along with their effects on the catalytic efficiency. The differences in the catalytic activity of the synthesized materials were analyzed through structural characterization, as well as assessments of the acid density and strength. Among the catalysts, Cr5BHC180 derived from bagasse presented the highest activity, achieving an HMF yield of 64.5% in an aqueous solvent system of dimethyl sulfoxide (DMSO) and saturated sodium chloride (NaCl) at 170 °C after 5 h. After four cycles, the HMF yield of Cr5BHC180 decreased to 38.7%. Characterization techniques such as N2 adsorption–desorption and Py-FTIR suggested that such a decline in the HMF yield is due to pore blockage and acid site coverage by humic by-products, as demonstrated by the fact that regeneration by calcination at 300 °C restored the HMF yield to 50.5%. Full article
(This article belongs to the Special Issue Carbohydrate Polymers: Synthesis, Preparation, Structural Characteristics and Applications)
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20 pages, 8874 KiB  
Article
Oxidation Resistance, Ablation Resistance, and Ablation Mechanism of HfC–B4C-Modified Carbon Fiber/Boron Phenolic Resin Ceramizable Composites
by Hairun Wen, Wei Zhang, Zongyi Deng, Xueyuan Yang and Wenchao Huang
Polymers 2025, 17(10), 1412; https://doi.org/10.3390/polym17101412 - 20 May 2025
Viewed by 163
Abstract
Thermal protection materials with excellent performance are critical for hypersonic vehicles. Carbon fiber/phenolic resin composites (Cf/Ph) have been widely used as thermal protection materials due to their high specific strength and ease of processing. However, oxidative failure limits the extensive applications [...] Read more.
Thermal protection materials with excellent performance are critical for hypersonic vehicles. Carbon fiber/phenolic resin composites (Cf/Ph) have been widely used as thermal protection materials due to their high specific strength and ease of processing. However, oxidative failure limits the extensive applications of Cf/Ph in harsh environments. In this paper, a novel hafnium carbide (HfC) and boron carbide (B4C)-modified Cf/Ph was fabricated via an impregnating and compression molding route. The synergistic effect of HfC and B4C on the thermal stability, flexural strength, microstructure, and phase evolution of the ceramizable composite was studied. The resulting ceramizable composites exhibited excellent resistance to oxidative corrosion and ablation behavior. The residual yield at 1400 °C and the flexural strength after heat treatment at 1600 °C for 20 min were 46% and 54.65 MPa, respectively, with an increase of 79.59% in flexural strength compared to that of the composites without ceramizable fillers. The linear ablation rate (LAR) and mass ablation rate (MAR) under a heat flux density of 4.2 MW/m2 for the 20 s were as low as −8.33 × 10−3 mm/s and 3.08 × 10−2 g/s. The ablation mechanism was further revealed. A dense B–C–N–O–Hf ceramic layer was constructed in situ as an efficient thermal protection barrier, significantly reducing the corrosion of the carbon fibers. Full article
(This article belongs to the Special Issue State of the Art and Perspectives of Polymer Science and Technology in China: 2nd Edition)
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21 pages, 6808 KiB  
Article
Flufenamic Acid-Loaded Electrospun Nanofibers Based on Chitosan/Poly(vinyl alcohol) Polymeric Composites for Drug Delivery in Biomedical Applications
by Kuppu Sakthi Velu, Mohammad Aslam, Ramachandran Srinivasan, Prathap Somu and Sonaimuthu Mohandoss
Polymers 2025, 17(10), 1411; https://doi.org/10.3390/polym17101411 - 20 May 2025
Viewed by 128
Abstract
Nanostructured drug-delivery systems with enhanced therapeutic potential have gained attention in biomedical applications. Here, flufenamic acid (FFA)-loaded chitosan/poly(vinyl alcohol) (CHS/PVA; CSPA)-based electrospun nanofibers were fabricated and characterized for antibacterial, anticancer, and antioxidant activities. The FFA-loaded CSPA (FCSPA) nanofibers were characterized by scanning electron [...] Read more.
Nanostructured drug-delivery systems with enhanced therapeutic potential have gained attention in biomedical applications. Here, flufenamic acid (FFA)-loaded chitosan/poly(vinyl alcohol) (CHS/PVA; CSPA)-based electrospun nanofibers were fabricated and characterized for antibacterial, anticancer, and antioxidant activities. The FFA-loaded CSPA (FCSPA) nanofibers were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction (XRD), and differential scanning calorimetry to evaluate their formation process, functional group interactions, and crystallinity. Notably, the average diameter of FCSPA nanofibers decreased with increasing CSPA contents (CSPA-1 to CSPA-3), indicating that FFA addition to CSPA-3 significantly decreased its diameter. Additionally, XRD confirmed the dispersion of FFA within the CSPA amorphous matrix, enhancing drug stability. FCSPA nanofibers exhibited a high swelling ratio (significantly higher than that of the CSPA samples). Biodegradation studies revealed that FCSPA exhibited accelerated weight loss after 72 h, indicating its improved degradation compared with those of other formulations. Furthermore, it exhibited a significantly high drug-encapsulation efficiency, ensuring sustained release. FCSPA nanofibers exhibited excellent antibacterial activity, inhibiting Staphylococcus aureus and Escherichia coli. Regarding anticancer activity, FCSPA decreased HCT-116 cell viability, highlighting its controlled drug-delivery potential. Moreover, FCSPA demonstrated superior antioxidation, scavenging DPPH free radicals. These findings highlight FCSPA nanofibers as multifunctional platforms with wound-healing, drug-delivery, and tissue-engineering potential. Full article
(This article belongs to the Special Issue Advances of Chitin and Chitosan-Based Materials: Preparation and Applications)
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27 pages, 715 KiB  
Review
Application of Molecularly Imprinted Polymers in the Analysis of Explosives
by Chenjie Wei, Lin Feng, Xianhe Deng, Yajun Li, Hongcheng Mei, Hongling Guo, Jun Zhu and Can Hu
Polymers 2025, 17(10), 1410; https://doi.org/10.3390/polym17101410 - 20 May 2025
Viewed by 218
Abstract
The detection of explosives is highly important for the investigation of explosion cases and public safety management. However, the detection of trace explosive residues in complex matrices remains a major challenge. Molecularly imprinted polymers (MIPs), which mimic the antigen–antibody recognition mechanism, can selectively [...] Read more.
The detection of explosives is highly important for the investigation of explosion cases and public safety management. However, the detection of trace explosive residues in complex matrices remains a major challenge. Molecularly imprinted polymers (MIPs), which mimic the antigen–antibody recognition mechanism, can selectively recognize and bind target explosive molecules. They offer advantages such as high efficiency, specificity, renewability, and ease of preparation, and they have shown significant potential for the efficient extraction and highly sensitive detection of trace explosive residues in complex matrices. This review comprehensively discusses the applications of MIPs in the analysis of explosives; systematically summarizes the preparation methods; and evaluates their performance in detecting nitroaromatic explosives, nitrate esters, nitroamine explosives, and peroxide explosives. Finally, this review explores the future potential of emerging technologies in enhancing the MIP-based analysis of explosives. The aim is to support the further application of MIPs in the investigation of explosion cases and safety management, providing more effective technical solutions for public safety. Full article
(This article belongs to the Special Issue New Advances in Molecularly Imprinted Polymer)
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20 pages, 2965 KiB  
Article
Bioactive Hydrogel Scaffolds Integrating Chitosan, Silk Fibroin, and Aloe vera Extract for Enhanced Cartilage Tissue Regeneration
by Witwisitpong Maneechan, Phassorn Khumfu, Pensri Charoensit, Areeya Tuanchai, Sukunya Ross, Gareth M. Ross, Jatuporn Ngoenkam and Jarupa Viyoch
Polymers 2025, 17(10), 1409; https://doi.org/10.3390/polym17101409 - 20 May 2025
Viewed by 237
Abstract
This study developed composite hydrogel scaffolds from chitosan (CS), silk fibroin (SF), and Aloe vera (AV) gel extract for cartilage tissue engineering. SF extracted from Nang-Laai silkworm cocoons showed high protein content (86.8%), while AV extract contained characteristic polysaccharides. Scaffolds with varying CS/SF/AV [...] Read more.
This study developed composite hydrogel scaffolds from chitosan (CS), silk fibroin (SF), and Aloe vera (AV) gel extract for cartilage tissue engineering. SF extracted from Nang-Laai silkworm cocoons showed high protein content (86.8%), while AV extract contained characteristic polysaccharides. Scaffolds with varying CS/SF/AV ratios were fabricated and evaluated for physicochemical and biological properties. Among all formulations, CS40/SF/AV (3.00%wt CS, 2.70%wt SF, 0.075%wt AV) exhibited superior porosity (72.23 ± 4.85%), pore size (79.57 ± 3.68 μm), and compressive strength, both in dry (6.67 ± 1.44 MPa) and wet states. It also showed controlled swelling (270%) and a stable degradation profile (55–57% over 21 days). FTIR and XRD confirmed successful component integration and semi-crystalline structure. In vitro, CS40/SF/AV supported chondrocyte adhesion, proliferation, and morphology retention over 28 days. Fluorescence imaging showed uniform cell distribution across the scaffold. These results highlight the CS40/SF/AV scaffold as a promising, biocompatible platform with optimal mechanical and structural properties for cartilage regeneration, offering potential for further in vivo applications. Full article
(This article belongs to the Special Issue Biomedical Applications of Intelligent Hydrogel 2nd Edition)
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19 pages, 2284 KiB  
Article
Applicability Domain of the Sens-Is In Vitro Assay for Testing the Skin Sensitization Potential of Rheology-Modifying Polymers
by Isabelle Hochar, Mickaël Puginier, Hervé Groux, Jérôme Guilbot, Françoise Cottrez and Alicia Roso
Polymers 2025, 17(10), 1408; https://doi.org/10.3390/polym17101408 - 20 May 2025
Viewed by 227
Abstract
Assessing the propensity of ingredients to induce skin sensitization through in vitro testing is crucial for worker and consumer safety. This is particularly important for novel and high-performance ingredients with complex structures, such as rheology-modifying polymers, which are extensively used in cosmetics, pharmaceuticals, [...] Read more.
Assessing the propensity of ingredients to induce skin sensitization through in vitro testing is crucial for worker and consumer safety. This is particularly important for novel and high-performance ingredients with complex structures, such as rheology-modifying polymers, which are extensively used in cosmetics, pharmaceuticals, and detergents. The Sens-Is assay has proven effective in distinguishing skin sensitizers from non-sensitizers for difficult-to-test ingredients when integrated into a multi-method in vitro approach. Therefore, the primary goal of this research was to explore whether the Sens-Is in vitro assay is suitable to evaluate rheology-modifying polymers. Fifteen structurally diverse rheology-modifying polymers, including natural polymers obtained by extraction, chemical synthesis, or biotechnology, spanning varying physical forms and concentrations, were evaluated. The results showed that most polymers were non-sensitizing, consistent with available in vivo data. Although polymer macromolecules generally exhibit limited skin sensitization potential due to their surface confinement, the Sens-Is assay permitted the detection of weak signals from secondary components or possible byproducts in specific cases. This work confirms Sens-Is as a useful tool in an overall approach to assessing the skin sensitization liability of polymers under development, but careful solvent selection is crucial to ensure accurate results and prevent potential overexposure due to polymer retention on the epidermal surface. Full article
(This article belongs to the Special Issue Eco-Friendly Polymers: Synthesis, Characterization and Applications, 3rd Edition)
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20 pages, 4646 KiB  
Article
The Production of High-Permeable and Macrovoid-Free Polysulfone Hollow Fiber Membranes and Their Utilization in CO2 Capture Applications via the Membrane-Assisted Gas Absorption Technique
by Pavel Țiuleanu, Artem A. Atlaskin, Kirill A. Smorodin, Sergey S. Kryuchkov, Maria E. Atlaskina, Anton N. Petukhov, Andrey V. Vorotyntsev, Nikita S. Tsivkovskiy, Alexander A. Sysoev and Ilya V. Vorotyntsev
Polymers 2025, 17(10), 1407; https://doi.org/10.3390/polym17101407 - 20 May 2025
Viewed by 168
Abstract
This present study covers a complex approach to study a hybrid separation technique: membrane-assisted gas absorption for CO2 capture from flue gases. It includes not only the engineering aspects of the process, particularly the cell design, flow organization, and process conditions, but [...] Read more.
This present study covers a complex approach to study a hybrid separation technique: membrane-assisted gas absorption for CO2 capture from flue gases. It includes not only the engineering aspects of the process, particularly the cell design, flow organization, and process conditions, but also a complex study of the materials. It covers the spinning of hollow fibers with specific properties that provide sufficient mass transfer for their implementation in the hybrid membrane-assisted gas absorption technique and the design of an absorbent with a new ionic liquid—bis(2-hydroxyethyl) dimethylammonium glycinate, which allows the selective capture of carbon dioxide. In addition, the obtained hollow fibers are characterized not only by single gas permeation but with regard to mixed gases, including the transfer of water vapors. A quasi-real flue gas, which consists of nitrogen, oxygen, carbon dioxide, and water vapors, is used to evaluate the separation efficiency of the proposed membrane-assisted gas absorption technique and to determine its ultimate performance in terms of the CO2 content in the product flow and recovery rate. As a result of this study, it is found that highly permeable fibers in combination with the obtained absorbent provide sufficient separation and their implementation is preferable compared to a selective but much less permeable membrane. Full article
(This article belongs to the Special Issue Innovative Polymers and Technology for Membrane Fabrication)
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17 pages, 3763 KiB  
Article
Epoxy–Aminated Lignin Impregnation Combined with Densification for Enhanced Mechanical Properties and Deformation Fixation of Wood
by Zhizun Gao, Jiayi Sun, Zhenke Wei, Fanjun Yu, Zhe Qiu, Zefang Xiao and Yonggui Wang
Polymers 2025, 17(10), 1406; https://doi.org/10.3390/polym17101406 - 20 May 2025
Viewed by 203
Abstract
Hot-pressing densification is an effective method to enhance the mechanical properties of wood; however, excessively high pressing temperatures can cause thermal degradation of wood components, compromising these improvements. In this study, aminated lignin (AL), with improved water solubility and reactive amino groups facilitating [...] Read more.
Hot-pressing densification is an effective method to enhance the mechanical properties of wood; however, excessively high pressing temperatures can cause thermal degradation of wood components, compromising these improvements. In this study, aminated lignin (AL), with improved water solubility and reactive amino groups facilitating crosslinking, was utilized as a bio-based amine curing agent for the water-soluble, low-molecular-weight epoxy compound polyethylene glycol diglycidyl ether (PEGDGE). The PEGDGE-AL modifier was applied for wood impregnation, followed by hot-pressing densification at a relatively low temperature of 120 °C, to enhance the mechanical properties of wood. The chemical composition of AL was analyzed using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and X-ray photoelectron spectroscopy (XPS). The gelation and curing behavior of the PEGDGE-AL modifier demonstrated its ability to readily form a network structure at both room temperature and elevated temperatures. The impact strength of densified wood (DW) modified with 12 wt% PEGDGE and 8 wt% AL, denoted as 12PEGDGE+8AL-DW, exhibited an impact strength of 15.2 kJ/m2, representing a 72% increase compared to untreated wood (UW). The modulus of rupture (MOR) and modulus of elasticity (MOE) reached 241.1 MPa and 14.6 GPa, respectively, corresponding to 60% and 75% improvements over UW. Furthermore, the 24 h water uptake and thickness swelling of 12PEGDGE+8AL-DW were 45.2% and 24.7%, which were 11% and 43% lower than those of water-impregnated and hot-pressed densified wood (W-DW), respectively. This study provides a low-temperature route for wood densification while contributing to the valorization of lignin in high-performance material applications. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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16 pages, 9992 KiB  
Article
Quantitative Dissection of Relaxation Processes in Hybrid Epoxy Composites: Combining Dielectric Spectroscopy with Activation Energy Analysis
by Xingqiao Li, Hongliang Zhang, Yansheng Bai, Hai Jin, Hong Wang, Kangle Li and Xiaonan Li
Polymers 2025, 17(10), 1405; https://doi.org/10.3390/polym17101405 - 20 May 2025
Viewed by 189
Abstract
The dielectric relaxation dynamics in polymer composites critically determine their functional performance in advanced electrical systems. This study systematically investigates hybrid epoxy composites comprising neat epoxy resin (EP) and paper-reinforced systems (EIP), modified with 10–50 wt% polypropylene glycol diglycidyl ether (PEGDGE) plasticizer. Through [...] Read more.
The dielectric relaxation dynamics in polymer composites critically determine their functional performance in advanced electrical systems. This study systematically investigates hybrid epoxy composites comprising neat epoxy resin (EP) and paper-reinforced systems (EIP), modified with 10–50 wt% polypropylene glycol diglycidyl ether (PEGDGE) plasticizer. Through synergistic application of differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (10−1–106 Hz), the quantitative relationships between plasticizer content, glass transition temperature (Tg), and dielectric relaxation processes were established. DSC analysis reveals a linear Tg dependence with increasing PEGDGE content, attributed to enhanced molecular mobility. Dielectric characterization demonstrates three distinct relaxation regimes: α-relaxation below Tg, interfacial polarization at epoxy/PEGDGE boundaries, and paper/epoxy interfacial effects in EIP systems. A quantitative dielectric relaxation model was developed based on complex modulus formalism, coupled with Vogel–Fulcher–Tammann (VFT) analysis of DC conductivity. Activation energy mapping through Arrhenius decomposition reveals three characteristic values: (1) 82.01–87.80 kJ/mol for α-relaxation, (2) 55.96–64.64 kJ/mol for epoxy/PEGDGE interfaces, and (3) 30.88–44.38 kJ/mol for epoxy/paper interfaces. Crucially, the plasticizer content modulates these activation energies, demonstrating its role in tailoring interfacial dynamics. Full article
(This article belongs to the Section Polymer Analysis and Characterization)
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16 pages, 2082 KiB  
Article
Antimicrobial Properties of a Novel PEGylated Copper Nanoparticle-Embedded Silicone Rubber with Potential for Use in Biomedical Applications
by Sara Ramírez Pastén, Carolina Paz Quezada, Carolina Arellano, Roberto M. Vidal, Alejandro Escobar, Faustino Alonso, Javier Villarroel, David A. Montero and María C. Paredes
Polymers 2025, 17(10), 1404; https://doi.org/10.3390/polym17101404 - 20 May 2025
Viewed by 544
Abstract
Background: Healthcare-associated infections (HAIs) significantly increase morbidity, mortality, and healthcare costs. Among HAIs, catheter-associated infections are particularly prevalent due to the susceptibility of catheters to microbial contamination and biofilm formation, especially with prolonged use. Biofilms act as infection reservoirs, complicating treatment and [...] Read more.
Background: Healthcare-associated infections (HAIs) significantly increase morbidity, mortality, and healthcare costs. Among HAIs, catheter-associated infections are particularly prevalent due to the susceptibility of catheters to microbial contamination and biofilm formation, especially with prolonged use. Biofilms act as infection reservoirs, complicating treatment and often requiring catheter removal, thus extending hospital stays and increasing costs. Recent technological advances in catheter design have focused on integrating antifouling and antimicrobial coatings to mitigate or prevent biofilm formation. Methods: We developed COPESIL®, a novel silicone rubber embedded with PEGylated copper nanoparticles designed to reduce microbial contamination on catheter surfaces. We conducted in vitro assays to evaluate the antimicrobial and antibiofilm efficacy of COPESIL® against pathogens commonly implicated in catheter-associated urinary tract infections. Additionally, the safety profile of the material was assessed through cytotoxicity evaluations using HepG2 cells. Results: COPESIL® demonstrated substantial antimicrobial activity, reducing contamination with Escherichia coli and Klebsiella pneumoniae by >99.9% and between 93.2% and 99.8%, respectively. Biofilm formation was reduced by 5.2- to 7.9-fold for E. coli and 2.7- to 2.8-fold for K. pneumoniae compared to controls. Cytotoxicity assays suggest the material is non-toxic, with cell viability remaining above 95% after 24 h of exposure. Conclusions: The integration of PEGylated copper nanoparticles into a silicone matrix in COPESIL® represents a promising strategy to enhance the antimicrobial properties of catheters. Future studies should rigorously evaluate the long-term antimicrobial efficacy and clinical safety of COPESIL®-coated catheters, with a focus on their impact on patient outcomes and infection rates in clinical settings. Full article
(This article belongs to the Special Issue Advanced Antibacterial Polymers and Their Composites)
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18 pages, 1894 KiB  
Article
Antifungal Efficacy and Surface Properties of Conventional and 3D-Printed Denture Base Materials Modified with Titanium Tetrafluoride (TiF4): In Vitro Study
by Zahra A. Alzaher, Fatimah A. Aldobais, Zainab Albazroun, Fatimah M. Alatiyyah, Reem Abualsaud, Haidar Alalawi, Ahmad M. Al-Thobity, Soban Q. Khan and Mohammed M. Gad
Polymers 2025, 17(10), 1403; https://doi.org/10.3390/polym17101403 - 20 May 2025
Viewed by 225
Abstract
Background: Candida albicans adhesion to denture base materials is a primary contributor to denture stomatitis. To address this issue, numerous studies have explored the incorporation of various additives into denture base resins to enhance their antifungal properties. Titanium tetrafluoride (TiF4) [...] Read more.
Background: Candida albicans adhesion to denture base materials is a primary contributor to denture stomatitis. To address this issue, numerous studies have explored the incorporation of various additives into denture base resins to enhance their antifungal properties. Titanium tetrafluoride (TiF4) is an inorganic fluoride compound that has proven antimicrobial properties but has not yet been tested with denture materials. This study aimed to evaluate the effect of TiF4 addition into different denture base materials on antifungal activity, surface roughness, hardness, and color properties. Methodology: A total of 200 disc-shaped specimens were prepared—100 heat-polymerized acrylic resins and 100 3D-printed NextDent resins. Four different concentrations of TiF4 were incorporated: 1 wt%, 2 wt%, 3 wt%, and 4 wt% for both resins, while one group of each resin remained unmodified as a control. All specimens were subjected to thermal cycling for 5000 cycles, and four tests were conducted: Candida albicans adherence, surface roughness, hardness, and color change. A scanning electron microscope (SEM) was used to prove Candida albicans colonies’ adhesion on the specimens’ surfaces, and Fourier-transformed infrared (FTIR) analysis was performed to show the presence of TiF4 in the resin material; data were analyzed using one-way ANOVA followed by a post hoc test (α = 0.05). Results: TiF4 significantly reduced the Candida albicans adhesion to heat-polymerized specimens (p < 0.001). Compared to the control group, the incorporation of TiF4 resulted in a substantial reduction in C. albicans colony counts, with reductions of approximately 97.6% in 1HP, 97.2% in 2HP, 97.4% in 3HP, and complete inhibition (100%) in 4HP. However, there was no significant difference between the 3D-printed ones (p = 0.913). Surface roughness, hardness, and color change of heat-polymerized groups were not significantly affected by TiF4 (p > 0.05) except the color of the group treated with 4% (p < 0.05). For the 3D-printed groups, no significant differences were detected between the groups regarding candida count, hardness was significantly increased at 2% TiF4 compared to the control (p = 0.002), and roughness was least with 4% TiF4, while the color varied significantly between the groups (p < 0.001). Conclusions: TiF4 addition decreased Candida albicans adhesion to heat-polymerized denture base materials but showed no antifungal effect on the 3D-printed resin. While roughness remained low in 3D-printed groups at higher concentrations. Hardness was not significantly altered in the heat-polymerized resin, whereas it increased significantly in the modified 3D-printed resin. Color stability was compromised at higher TiF4 concentrations, particularly in the 3D-printed groups. The type of denture base material and TiF4 concentration both influenced antifungal activity and denture surface properties. Full article
(This article belongs to the Special Issue Advances in Polymeric Dental Materials)
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20 pages, 2249 KiB  
Article
Mechanical Properties, Thermal Stability, and Formaldehyde Emission Analysis of Nanocellulose-Reinforced Urea–Formaldehyde Resin and Its Mechanism
by Xue Deng, Zhu Liu, Zhongwei Wang, Zhigang Wu, Dan Li, Shoulu Yang, Shiqiang He and Ning Ji
Polymers 2025, 17(10), 1402; https://doi.org/10.3390/polym17101402 - 20 May 2025
Viewed by 164
Abstract
In this research, a urea–formaldehyde (UF) resin was modified with nanocrystalline cellulose (NCC) and nanofibrillated cellulose (CNF), and the properties of the modified resin were comprehensively evaluated by combining the techniques of infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric [...] Read more.
In this research, a urea–formaldehyde (UF) resin was modified with nanocrystalline cellulose (NCC) and nanofibrillated cellulose (CNF), and the properties of the modified resin were comprehensively evaluated by combining the techniques of infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results showed that (1) the introduction of NCC and CNF significantly changed the hydrogen bonding network of the UF resin, in which CNF enhanced the internal hydrogen bonding of the resin through its long-chain structure and elevated the cross-linking density. NCC increased the crystallinity of the resin, while CNF enhanced the overall performance of the resin by improving its dispersion. (2) The composite curing agent system significantly reduced the curing temperature of the resin, resulting in a more homogeneous and efficient curing reaction, and the CNF-modified UF exhibited better thermal stability. (3) The addition of NCC and CNF significantly improved the dry and water-resistant bonding strengths of the resins. In addition, the use of complex curing agent further enhanced the bonding strength, especially in the CNF-modified system; the addition of complex curing agent increased the dry bonding strength to 1.60 MPa, and the water-resistant bonding strength reached 1.13 MPa, which showed a stronger cross-linking network and structural stability. (4) The addition of NCC and CNF led to a significant reduction in the free formaldehyde content of UF resins, resulting in respective levels of 0.17% and 0.14%. For plywood bonded with the CNF-modified UF resin, formaldehyde emissions were measured at 0.35 mg/L, which were markedly lower than the 0.54 mg/L of the unmodified sample. This further highlights CNF’s effectiveness in minimizing formaldehyde release. (5) Overall, CNF is superior to NCC in improving the thermal stability, bonding strength, water resistance, formaldehyde release, and overall performance of the resin. The use of complex curing agents not only optimizes the curing process of the resin but also further enhances the modification effect, especially for CNF-modified resins, which show more significant performance advantages. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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16 pages, 2796 KiB  
Article
Optimization of Printing Parameters for Self-Lubricating Polymeric Materials Fabricated via Fused Deposition Modelling
by Peiyang Zhang, Feiyang He and Muhammad Khan
Polymers 2025, 17(10), 1401; https://doi.org/10.3390/polym17101401 - 20 May 2025
Viewed by 144
Abstract
This study investigated the feasibility of fabricating self-lubrication material using fused deposition modelling (FDM) technology, focusing on the influence of printing parameters on tribological performance. Experiments were conducted using PA and ABS materials, with varying printing speed, infill density, and layer height across [...] Read more.
This study investigated the feasibility of fabricating self-lubrication material using fused deposition modelling (FDM) technology, focusing on the influence of printing parameters on tribological performance. Experiments were conducted using PA and ABS materials, with varying printing speed, infill density, and layer height across four levels. The research established regression equations and fitted curves to describe the relationship between printing parameters and the coefficient of friction (CoF). Validation experiments demonstrated the reliability of the models, with errors within 10%. The results indicate that reducing printing speed and increasing infill density enhance surface quality, with infill density exerting a more significant effect. The influence of layer height on surface quality depends on the printer characteristics, making precise quantification challenging. Additionally, this study confirms that resin-based samples produced via FDM exhibit self-lubricating potential. These findings contribute to the optimization of FDM-printed structures by balancing surface quality and tribological performance. Full article
(This article belongs to the Special Issue Tribological Properties of Polymer Materials)
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18 pages, 5857 KiB  
Article
Self-Powered Triboelectric Ethanol Sensor Based on CuO-Doped Electrospun PVDF Fiber with Enhanced Sensing Performance
by Quanyu He, Hyunwoo Cho, Inkyum Kim, Jonghwan Lee and Daewon Kim
Polymers 2025, 17(10), 1400; https://doi.org/10.3390/polym17101400 - 20 May 2025
Viewed by 228
Abstract
Electrospinning techniques have been widely applied in diverse applications, such as biocompatible membranes, energy storage systems, and triboelectric nanogenerators (TENGs), with the capability to incorporate other functional materials to achieve specific purposes. Recently, gas sensors incorporating doped semiconducting materials fabricated by electrospinning have [...] Read more.
Electrospinning techniques have been widely applied in diverse applications, such as biocompatible membranes, energy storage systems, and triboelectric nanogenerators (TENGs), with the capability to incorporate other functional materials to achieve specific purposes. Recently, gas sensors incorporating doped semiconducting materials fabricated by electrospinning have been extensively investigated. TENGs, functioning as self-powered energy sources, have been utilized to drive gas sensors without external power supplies. Herein, a self-powered triboelectric ethanol sensor (TEES) is fabricated by integrating a TENG and an ethanol gas sensor into a single device. The proposed TEES exhibits a significantly improved response time and lower detection limit compared to published integrated triboelectric sensors. The device achieves an open-circuit voltage of 51.24 V at 800 rpm and a maximum short-circuit current of 7.94 μA at 800 rpm. Owing to the non-contact freestanding operating mode, the TEES shows no significant degradation after 240,000 operational cycles. Compared with previous studies that integrated TENGs and ethanol sensors, the proposed TEES demonstrated a marked improvement in sensing performance, with a faster response time (6 s at 1000 ppm) and a lower limit of detection (10 ppm). Furthermore, ethanol detection is enabled by modulating the gate terminal of an IRF840 metal-oxide semiconductor field-effect transistor (MOSFET), which controls the illumination of a light-emitting diode (LED). The LED is extinguished when the electrical output decreases below the setting value, allowing for the discrimination of intoxicated states. These results suggest that the TEES provides a promising platform for self-powered, high-performance ethanol sensing. Full article
(This article belongs to the Section Polymer Fibers)
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14 pages, 1108 KiB  
Article
Design of a Dual Molecular Weight Polymer Gel for Water-Shutoff Treatment in a Reservoir with Active Aquifer
by Maria Isabel Sandoval Martinez, Valeria Salgado Carabali, Andres Ramirez, Arlex Chaves-Guerrero and Samuel Muñoz Navarro
Polymers 2025, 17(10), 1399; https://doi.org/10.3390/polym17101399 - 19 May 2025
Viewed by 306
Abstract
This study presents the formulation and evaluation of a dual molecular weight polymer gel system composed of partially hydrolyzed polyacrylamide (HPAM) and crosslinked with polyethyleneimine (PEI) for water shut-off applications. A soft gel, designed for deep reservoir penetration, was formulated using 5000 ppm [...] Read more.
This study presents the formulation and evaluation of a dual molecular weight polymer gel system composed of partially hydrolyzed polyacrylamide (HPAM) and crosslinked with polyethyleneimine (PEI) for water shut-off applications. A soft gel, designed for deep reservoir penetration, was formulated using 5000 ppm high-molecular-weight HPAM, while a rigid gel for near-wellbore blockage combined 5000 ppm high- and 5000 ppm low-molecular-weight HPAM. The gel system was designed at 65 °C, with an initial gelation time exceeding 8 h and viscosity values below 15 cP before gelation, ensuring ease of injection. Laboratory assessments included bottle testing, rotational and oscillatory rheological measurements, and core flooding to determine residual resistance factors (RRFs). The soft gel achieved a final strength of Grade D (low mobility), while the rigid gel reached Grade G (moderate deformability, immobile), according to Sydansk’s classification. RRF values reached 93 for the soft gel and 185 for the rigid gel, with both systems showing strong washout resistance and water shut-off efficiencies above 95%. These results demonstrate the potential of the HPAM/PEI gel system as an effective solution for conformance control in mature reservoirs with active aquifers. Full article
(This article belongs to the Special Issue Synthesis, Structure, Characterization and Application of Polymer Networks and Gels)
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26 pages, 6708 KiB  
Article
Development of Optimal Conditions for Synthesis of Molecularly Imprinted Polymers for Effective Terbium Sorption
by Laura Agibayeva, Yevgeniy Melnikov, Ayakoz Berdaly and Ruslan Kondaurov
Polymers 2025, 17(10), 1398; https://doi.org/10.3390/polym17101398 - 19 May 2025
Viewed by 281
Abstract
Molecularly imprinted polymers (MIPs) as well as non-imprinted polymers (NIPs) were synthesized for selective sorption of lead and terbium. The ratio of raw monomers for the terbium–MIPs’ synthesis was optimized based on the results of the synthesis of lead–MIP. It was found that [...] Read more.
Molecularly imprinted polymers (MIPs) as well as non-imprinted polymers (NIPs) were synthesized for selective sorption of lead and terbium. The ratio of raw monomers for the terbium–MIPs’ synthesis was optimized based on the results of the synthesis of lead–MIP. It was found that the molar ratio of template/monomer/monomer/cross-linker = 1:5:5:8 was the most accurate for successful synthesis of the target MIP. As a result, the yields of the MIP and NIP on terbium were 59.3% and 61.2%, respectively. The structure of the imprinted samples was determined by FTIR spectroscopy. SEM analysis of the imprinted structures showed that the Tb–MIP contained a large number of pores compared to the NIP. The size of these pores ranged from 0.779 μm to 1.874 μm. The results of sorption experiments showed that the adsorption efficiency of Tb–MIP was seven times higher than that of NIP: the sorption degree was 70.80% for MIP and 9.95% for NIP. The imprinting factor was calculated and was equal to 7.06. The sorption process was described by the Radushkevich and pseudo-second-order kinetic models. It was shown that sorption by NIP occurred with a fast saturation of a lower Tb concentration, and the MIP’s sorption passed slower and more efficiently. The desorption degrees of Tb–MIP and NIP were 90.15% and 52.67%, respectively. Full article
(This article belongs to the Special Issue New Advances in Molecularly Imprinted Polymer)
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30 pages, 9400 KiB  
Review
Visualization of Single Polymer Chains with Atomic Force Microscopy: A Review
by Maria Pop, Otto Todor-Boer and Ioan Botiz
Polymers 2025, 17(10), 1397; https://doi.org/10.3390/polym17101397 - 19 May 2025
Viewed by 214
Abstract
Single-chain atomic force microscopy has emerged as a powerful and highly specialized technique, enabling the direct observation and analysis of various isolated polymer chains at the nano and micro scales. This work reviews the most relevant experimental cases utilizing this technique, aiming to [...] Read more.
Single-chain atomic force microscopy has emerged as a powerful and highly specialized technique, enabling the direct observation and analysis of various isolated polymer chains at the nano and micro scales. This work reviews the most relevant experimental cases utilizing this technique, aiming to shine light on the understanding of the physical appearance of freshly synthesized polymer chains, reveal unique chain conformations and related transitions, decipher the processes of polymer crystallization and self-assembly, study the mechanisms of polymer adsorption and desorption, observe the formation of single-chain nanoparticles, and explore many other related phenomena. Full article
(This article belongs to the Section Polymer Chemistry)
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19 pages, 1936 KiB  
Article
Enhancing the Sensory Quality, Stability, and Shelf Life of Baobab Fruit Pulp Drinks: The Role of Hydrocolloids
by Abdullahi Idris Muhammad, Abdulrashid Rilwan, Zahrau Bamalli Nouruddeen, Ovinuchi Ejiohuo and Nasser Al-Habsi
Polymers 2025, 17(10), 1396; https://doi.org/10.3390/polym17101396 - 19 May 2025
Viewed by 401
Abstract
Baobab (Adansonia digitata L.) fruit pulp (BFP) is particularly noted for its high concentrations of bioactive compounds, including polyphenols, vitamins (notably vitamin C), and dietary fiber, surpassing common fruits such as oranges in ascorbic acid content. Despite its long-standing use in local [...] Read more.
Baobab (Adansonia digitata L.) fruit pulp (BFP) is particularly noted for its high concentrations of bioactive compounds, including polyphenols, vitamins (notably vitamin C), and dietary fiber, surpassing common fruits such as oranges in ascorbic acid content. Despite its long-standing use in local communities as a functional food ingredient, BFP drinks face significant challenges related to their sensory parameters and shelf life, particularly due to rapid microbial growth under tropical conditions. This study investigated the effects of two hydrocolloids, xanthan gum (XG) and carboxymethyl cellulose (CMC), on the viscosity, shelf-life stability, and consumer acceptance of BFP drinks. Seven samples were formulated with these hydrocolloids at different concentrations, namely, BXG1 (95% BFP:5% XG), BXG2 (90% BFP:10% XG), BXG3 (85% BFP:15% XG), BCMC1 (95% BFP:5% CMC), BCMC2 (90% BFP:10% CMC), and BCMC3 (85% BFP:15% CMC), alongside a control sample (100% BFP) and a commercially synthetic drink (CSD) for comparison. The results indicate that BFP drink sample (BXG1) stored under refrigeration (4 °C) for up to 14 days retains acceptable sensory qualities with minimal microbial growth (9 CFU/mL). However, storing at room temperature (ca. 25 ± 2 °C) led to rapid microbial proliferation (oral observation) within four days. These findings also confirm that BFP drinks can provide significant nutritional value, offering 330.64 kcal/100 g of metabolizable energy. This study suggests that, while BFP drinks offer several healthy benefits, enhancing their stability using hydrocolloids and appropriate storage conditions is essential. Future studies should focus on the incorporation of natural preservatives to enhance their stability while preserving their nutritional integrity. Full article
(This article belongs to the Special Issue Polymeric Materials in Food Science)
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Article
Preparation and Application of Humidity-Adaptive Wooden Artifact Crack Consolidants Based on Lignin–Epoxy Acrylate
by Qijun Huang, Wangting Wu, Yingzhu Wang and Jianrui Zha
Polymers 2025, 17(10), 1395; https://doi.org/10.3390/polym17101395 - 19 May 2025
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Abstract
Due to compatibility issues between traditional reinforcing materials and the substrate of museum wooden artifacts, interface failure occurs after crack reinforcement, particularly under dry and wet cycling conditions. This significantly compromises the durability of reinforcement. To resolve this issue, dealkalized lignin was grafted [...] Read more.
Due to compatibility issues between traditional reinforcing materials and the substrate of museum wooden artifacts, interface failure occurs after crack reinforcement, particularly under dry and wet cycling conditions. This significantly compromises the durability of reinforcement. To resolve this issue, dealkalized lignin was grafted onto epoxy acrylate (LEA) to synthesize a novel consolidant with both humidity responsiveness and mechanical compatibility. The resulting LEA exhibited excellent multilayer adsorption capability and demonstrated synchronous and uniform hygroscopic expansion behavior, closely matching that of archeological wood. DMA revealed that LEA2 has an elastic modulus of 261.58 MPa and a Poisson’s ratio of 0.35, comparable to artificially degraded wood, effectively mitigating interface stress caused by rigidity differences. Furthermore, LEA effictively reinforced micron-scale cracks while maintaining the original microstructure of the wooden artifact. This material provides a promising solution to the compatibility challenges of traditional consolidants under humidity fluctuations and offers a new approach for the stable preservation of museum wooden artifacts. Full article
(This article belongs to the Section Polymer Applications)
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