Polymers

20 pages, 2477 KiB

Open AccessArticle

Digital Twin-Enabled Extrusion Control for High-Fidelity Printing of Polymers

by Kantawatchr Chaiprabha, Chaiwuth Sithiwichankit, Worathris Chungsangsatiporn, Gridsada Phanomchoeng and Ratchatin Chancharoen

Polymers 2025, 17(16), 2215; https://doi.org/10.3390/polym17162215 - 13 Aug 2025

Abstract

Direct ink writing (DIW) has emerged as a powerful technique for functional-structure fabrication. However, its application to materials with heterogeneous or time-dependent rheology remains limited. This study introduces dual-mode electropneumatic extrusion, supported by a real-time digital twin. This platform integrates a motorized pneumatic [...] Read more.

Direct ink writing (DIW) has emerged as a powerful technique for functional-structure fabrication. However, its application to materials with heterogeneous or time-dependent rheology remains limited. This study introduces dual-mode electropneumatic extrusion, supported by a real-time digital twin. This platform integrates a motorized pneumatic cylinder with an electropneumatic pressure regulator, enabling continuous blending of pressure and displacement control. System performance is evaluated across five material characteristics: homogeneity, heterogeneity, time-dependent rheology, self-curing ability, and thermoplasticity. The results demonstrate that feedback current control reduces the linewidth variability to ≈2% and settling time to <250 ms, even under four-fold increases in viscosity. Adaptive pressure ramps restore variability to ≤4% throughout material curing, while hybrid velocity–pressure operation maintains variability at ≤4% and a pore geometry error below 4% over 20 layers. These findings establish a robust framework for rheology-adaptive DIW and offer practical guidelines for implementing dual-mode control in high-throughput, multi-nozzle applications. Full article

(This article belongs to the Special Issue Biomedical Applications of Intelligent Hydrogel 2nd Edition)

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12 pages, 2884 KiB

Open AccessArticle

High-Detectivity Organic Photodetector with InP Quantum Dots in PTB7-Th:PC₇₁BM Ternary Bulk Heterojunction

by Eunki Baek, Sung-Yoon Joe, Hyunbum Kang, Chanho Jeong, Hyunjong Lee, Insung Choi, Sohee Kim, Sangjun Park, Dongwook Kim, Jaehoon Park, Jae-Hyeon Ko, Gae Hwang Lee and Youngjun Yun

Polymers 2025, 17(16), 2214; https://doi.org/10.3390/polym17162214 - 13 Aug 2025

Abstract

Organic photodetectors (OPDs) offer considerable promise for low-power, solution-processable biosensing and imaging applications; however, their performance remains limited by spectral mismatch and interfacial trap states. In this study, a highly sensitive polymer photodiode was developed via trace incorporation (0.8 wt%) of InP/ZnSe/ZnS quantum [...] Read more.

Organic photodetectors (OPDs) offer considerable promise for low-power, solution-processable biosensing and imaging applications; however, their performance remains limited by spectral mismatch and interfacial trap states. In this study, a highly sensitive polymer photodiode was developed via trace incorporation (0.8 wt%) of InP/ZnSe/ZnS quantum dots (QDs) into a PTB7-Th:PC₇₁BM bulk heterojunction (BHJ) matrix. This QD doping approach enhanced the external quantum efficiency (EQE) across the 540–660 nm range and suppressed the dark current density at −2 V by passivating interface trap states. Despite a slight decrease in optical absorption at the optimized composition, the internal quantum efficiency (IQE) increased significantly from ~80% to nearly 95% resulting in a net EQE improvement. This suggests that QD incorporation improved charge transport without compromising charge separation efficiency. As a result, the device achieved a specific detectivity (D*) of 1.8 × 10¹³ Jones, representing a 93% improvement over binary BHJs, along with an ultra-low dark current density of 7.76 × 10⁻¹⁰ A/cm². Excessive QD loading, however, led to optical losses and increased dark current, underscoring the need for precise compositional control. Furthermore, the enhanced detectivity led to a 4 dB improvement in the signal-to-noise ratio (SNR) of photoplethysmography (PPG) signals in the target wavelength range, enabling more reliable biophotonic sensing without increased power consumption. This work demonstrates that QD-based spectral and interfacial engineering offers an effective and scalable route for advancing the performance of OPDs, with broad applicability to low-power biosensors and high-resolution polymer–QD imaging systems. Full article

(This article belongs to the Special Issue Polymer Semiconductors for Flexible Electronics)

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18 pages, 4322 KiB

Open AccessArticle

Development of Eco-Friendly Silane-Treated Rice Flour/PBS Biocomposites with ENR-50 as a Compatibilizer: A Study on Phase Morphology, Properties and Biodegradation

by Thritima Sritapunya, Apaipan Rattanapan, Surakit Tuampoemsab and Pornsri Sapsrithong

Polymers 2025, 17(16), 2213; https://doi.org/10.3390/polym17162213 - 13 Aug 2025

Abstract

This study investigated the development of biocomposites for use as packaging and film in everyday applications. The utilization of rice flour (RF) as a cheap natural filler in the production of polybutylene succinate (PBS) biocomposites has been shown to reduce environmental issues caused [...] Read more.

This study investigated the development of biocomposites for use as packaging and film in everyday applications. The utilization of rice flour (RF) as a cheap natural filler in the production of polybutylene succinate (PBS) biocomposites has been shown to reduce environmental issues caused by non-biodegradable plastic waste. The effect of rice flour content on the morphology and properties of PBS and RF biocomposites was comprehensively evaluated. Different amounts of rice flour were considered (0, 10, 20, 30, 40, and 50 phr), and a silane coupling agent and epoxidized natural rubber (ENR-50: 1 phr) were used as interfacial agents to improve compatibility between the matrix (PBS) and filler (RF). The PBS/RF biocomposites were prepared using a two-roll mill and shaped into test specimens and films using a compression molding machine. Batches of the composites containing different amounts of RF were prepared in accordance with the standards, and their morphology and properties, including mechanical properties, density, water absorption, and soil burial degradation, were evaluated. The results revealed that the incorporation of silane-treated RF filler and ENR-50 compatibilizer led to notable improvements in mechanical properties, particularly in tensile modulus, flexural strength, flexural modulus, and hardness. A significant improvement in mechanical performance was observed as the RF content increased, with the highest value recorded at the 50 phr loading. The enhancements observed in the composite properties are due to the inherent rigidity of the RF filler and its improved compatibility with the PBS matrix, which together contribute to a stronger and more efficient material. Additionally, the percentage of water absorption in the PBS/RF biocomposites increased with higher RF content. The results from the soil burial test demonstrated that increasing the RF content positively influenced the biodegradability of the PBS/RF biocomposite materials. Full article

(This article belongs to the Special Issue Biodegradable Polymers in Sustainable and Biomedical Applications)

15 pages, 2582 KiB

Open AccessArticle

Investigation of Composition, Structure, Electrical Properties, and Ageing Resistance of Conductive Flocked Fabric for Automotive Applications

by Matilde Arese, Elio Sarotto, Antonino Domenico Veca, Vito Guido Lambertini, Daniele Nardi, Martina Sandigliano, Federico Cesano and Valentina Brunella

Polymers 2025, 17(16), 2212; https://doi.org/10.3390/polym17162212 - 13 Aug 2025

Abstract

The growing development of conductive functionalised textiles has attracted the interest of the automotive industry, which is seeking innovative solutions for seamless and futuristic interior design aimed at improving both vehicle aesthetics and user experience. In line with this trend, the present work [...] Read more.

The growing development of conductive functionalised textiles has attracted the interest of the automotive industry, which is seeking innovative solutions for seamless and futuristic interior design aimed at improving both vehicle aesthetics and user experience. In line with this trend, the present work investigates the electrical performances of two conductive flocked yarns, one incorporating silver-coated fibres and the other carbon black-based fibres, for potential application in smart automotive interiors. The stability of their electrical properties was also evaluated under thermal ageing and mechanical stress conditions. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and field emission scanning electron microscopy (FE-SEM) investigations provided information about the composition and structural properties of the yarns. Silver-based yarns demonstrated superior conductivity and thermal stability. In contrast, carbon-black yarns exhibited lower electrical performance and increased sensitivity to ageing due to filler agglomeration. A multitouch capacitive sensor prototype was also developed using the silver-based fabric and successfully integrated into a microcontroller platform. The results demonstrate the suitability of conductive flocked textiles for durable, low-voltage human–machine interfaces requiring robust, flexible, and responsive textile-based control surfaces, such as automotive applications, consumer electronics, and wearable technology. Full article

(This article belongs to the Section Smart and Functional Polymers)

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16 pages, 5296 KiB

Open AccessArticle

The Effect of the Fresh Latex Ratio on the Composition and Properties of Bio-Coagulated Natural Rubber

by Jianwei Li, Honghai Huang, Li Ding, Tuo Dai, Haoran Geng, Tao Zhao, Liguang Zhao, Fan Wu and Hongxing Gui

Polymers 2025, 17(16), 2211; https://doi.org/10.3390/polym17162211 - 13 Aug 2025

Abstract

By proportionally blending fresh latex from PR107, Reyan 72059, and Reyan 73397, and employing both acid- and enzyme-assisted microbial coagulation methods, this study analyzed the effects of the specific latex formulation on the following: physicochemical properties, non-rubber components, molecular weight and distribution, vulcanization [...] Read more.

By proportionally blending fresh latex from PR107, Reyan 72059, and Reyan 73397, and employing both acid- and enzyme-assisted microbial coagulation methods, this study analyzed the effects of the specific latex formulation on the following: physicochemical properties, non-rubber components, molecular weight and distribution, vulcanization characteristics of compounded rubber, and physical–mechanical properties of vulcanized natural rubber. The results indicate that, compared to acid-coagulated natural rubber, enzyme-assisted microbial coagulated natural rubber exhibits slightly lower levels of volatile matter, impurities, plasticity retention index (PRI), nitrogen content, calcium ions (Ca²⁺), iron ions (Fe³⁺), and fatty acid content. Conversely, it demonstrates higher values in ash content, initial plasticity (P₀), Mooney viscosity (M_L(1+4)), acetone extract, magnesium ions (Mg²⁺), copper ions (Cu²⁺), manganese ions (Mn²⁺), gel content, molecular weight and distribution, and glass transition temperature (Tg). With the increase in the proportion of PR107 and Reyan 72059 fresh latex, the ash content, volatile matter content, fatty acid content, gel content, and dispersion coefficient (PDI) of natural rubber gradually decrease, while the impurity content, PRI, nitrogen content, weight-average molecular weight (Mw), and number-average molecular weight (Mn) gradually increase. Compared to acid-coagulated natural rubber compounds, enzyme-assisted microbial-coagulated natural rubber compounds exhibit higher minimum torque (M_L) and maximum torque (M_H), but shorter scorch time (t₁₀) and optimum cure time (t₉₀). Furthermore, as the proportion of PR107 and Reyan 72059 fresh latex increases, the ML of the compounds gradually decreases. In pure rubber formulations, enzyme-assisted microbial-coagulated natural rubber vulcanizates demonstrate higher tensile strength, tear strength, modulus at 300%, and Shore A hardness compared to acid-coagulated natural rubber vulcanizates. When the fresh latex ratio of PR107, Reyan 72059, and Reyan 73397 is 1:1:3, the tensile strength and 300% modulus of the natural rubber vulcanizates reach their maximum values. In carbon black formulations, the tensile strength and tear strength of enzyme-assisted microbial-coagulated natural rubber vulcanizates are significantly higher than those of acid-coagulated natural rubber vulcanizates in pure rubber formulations, with the increase exceeding that of other samples. Full article

(This article belongs to the Special Issue Additive Agents for Polymer Functionalization Modification)

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19 pages, 4348 KiB

Open AccessArticle

Manufacturing of Polymer–Metal Composite by Fused Filament Fabrication: Adhesion of PLA and PETG on Aluminum

by Miguel Campos-Jurado, Óscar Rodríguez-Alabanda and Guillermo Guerrero-Vacas

Polymers 2025, 17(16), 2210; https://doi.org/10.3390/polym17162210 - 13 Aug 2025

Abstract

The formation of metal–polymer composites by 3D printing PLA and PETG onto EN AW-5182 H111 aluminum substrates without the use of adhesives was investigated. Four surface treatments were evaluated on the metal substrate (fine sanding, coarse sanding, abrasive blasting, and acid etching), over [...] Read more.

The formation of metal–polymer composites by 3D printing PLA and PETG onto EN AW-5182 H111 aluminum substrates without the use of adhesives was investigated. Four surface treatments were evaluated on the metal substrate (fine sanding, coarse sanding, abrasive blasting, and acid etching), over which a polymer primer—prepared from PLA and PETG solutions—was applied. Subsequently, test specimens were fabricated using the same polymer through material extrusion (MEX) with filaments. Adhesion strength between the printed polymer and the metal substrate was assessed through perpendicular tensile, lap shear, and three-point bending tests. The 16-condition experimental matrix combined surface treatment, primer thickness, and bed temperature and was replicated for each test. Peak tensile and shear strengths confirmed the effectiveness of the proposed strategy, with PETG consistently showing a higher interfacial performance than PLA. ANOVA analysis identifies primer layer thickness (p = 0.023) and loading type (p = 0.031) as statistically significant variables. The results suggest that either abrasive or acid pretreatment, combined with a primer thickness ≥ 80 µm and moderate bed temperatures (65 °C for PLA and 90 °C for PETG), enables the fabrication of robust metal–polymer joints, which are particularly resistant to shear stress and suitable for industrial applications. Full article

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

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16 pages, 1896 KiB

Open AccessArticle

Modeling Approach to Calculate the Orientation of Liquid Crystal Polymers in a Flow Channel Under Varying Boundary Conditions

by Gernot Zitzenbacher

Polymers 2025, 17(16), 2209; https://doi.org/10.3390/polym17162209 - 13 Aug 2025

Abstract

Thermotropic liquid crystal polymers comprise rigid chain segments called mesogens. This study presents a modeling approach to simulate the orientation of these mesogens in a flow channel with a rectangular cross section under no slip and wall slip boundary conditions. Rigid rods with [...] Read more.

Thermotropic liquid crystal polymers comprise rigid chain segments called mesogens. This study presents a modeling approach to simulate the orientation of these mesogens in a flow channel with a rectangular cross section under no slip and wall slip boundary conditions. Rigid rods with finite length and an initial orientation are proposed. The interactions between the velocity field in the flow channel and these rods are modeled to simulate orientation. Moreover, a highly oriented boundary layer can be simulated. Orientation occurs in the flow direction close to the die wall under the no slip condition due to the high shear rate. As the distance from the die wall increases, the orientation decreases. Wall slip effectuates a more uniform orientation and causes a delay in the development of the highly oriented boundary layer. The thickness profile of this layer exhibits a shape that is analogous to that of a root function. To ensure products with high mechanical properties, it is essential to orient the mesogens at a high level in the die during manufacturing. The presented model enables the prediction of orientation in the flow channel. Therefore, this model is a useful tool to design the process in the right way to reach this goal. Full article

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15 pages, 2077 KiB

Open AccessArticle

Effect of Fabrication Route on the Mechanical Properties of Polylactic Acid (PLA) Composites with Diatom Earth (DE)

by Adrian Dubicki, Magdalena Pantoł and Krzysztof Jan Kurzydłowski

Polymers 2025, 17(16), 2208; https://doi.org/10.3390/polym17162208 - 13 Aug 2025

Abstract

Polylactide (PLA) that is reinforced with diatomaceous earth (DE) is a promising and eco-friendly material with high engineering potential. This article provides a comprehensive overview of various PLA types and processing methods for PLA + DE composites. This study aimed to determine the [...] Read more.

Polylactide (PLA) that is reinforced with diatomaceous earth (DE) is a promising and eco-friendly material with high engineering potential. This article provides a comprehensive overview of various PLA types and processing methods for PLA + DE composites. This study aimed to determine the mechanical strength limits of PLA + DE composites using two PLA grades—amorphous PLE 005-A and semi-crystalline Ingeo 4043D—that are each filled with Perma-Guard DE 5, 10, and 15% by weight, and two manufacturing methods, injection molding (IM) and additive manufacturing (3DP), using fused filament fabrication (FFF). The mechanical properties were assessed through static tensile tests in accordance with ISO 527-1 and compared with values reported in the literature. The results indicate a linear increase in stiffness (Young’s modulus) with increasing DE content. This is accompanied by a reduction in maximum tensile strength (σ_max) and elongation at break (ε_b). The highest Young’s modulus, around 4.65 GPa, was observed for injection-molded, semi-crystalline PLA with a 15% by weight DE. The greatest tensile strength, approx. 72 MPa, was achieved for printed, semi-crystalline PLA without filler. Furthermore, 3D printing achieved a tensile strength and stiffness comparable to injection molding, though the latter ensured significantly better ductility. These findings provide a basis for adjusting the PLA + DE composite properties to specific applications by selecting the matrix type, DE content, and manufacturing method. Full article

(This article belongs to the Special Issue Physicochemical Properties of Polymer Composites)

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20 pages, 8336 KiB

Open AccessArticle

Exploring Biodegradable Polymeric Nanocomposite Films for Sustainable Food Packaging Application

by Nikolay Estiven Gomez Mesa, Alis Yovana Pataquiva-Mateus and Youhong Tang

Polymers 2025, 17(16), 2207; https://doi.org/10.3390/polym17162207 - 13 Aug 2025

Abstract

In this study, a bio-nanocomposite integrating calcium caseinate, modified starch, and bentonite nanoclay was formulated and synthesized into film form via solution casting. Glycerol was incorporated for plasticization, and polyvinyl alcohol (PVA) was used to enhance the structural and chemical attributes of the [...] Read more.

In this study, a bio-nanocomposite integrating calcium caseinate, modified starch, and bentonite nanoclay was formulated and synthesized into film form via solution casting. Glycerol was incorporated for plasticization, and polyvinyl alcohol (PVA) was used to enhance the structural and chemical attributes of the material. The addition of PVA and bentonite notably improved the mechanical strength of the casein-based matrix, showing up to a 30% increase in tensile strength compared to similar biopolymer formulations. Water vapor permeability was significantly reduced when compared to previously reported casein–starch formulations, evidencing the barrier-positive effects of bentonite nanostructures. The microbial analysis confirmed that the quantity of bacterial colonies remained within permissible levels for non-antimicrobial biodegradable films; however, further antibacterial evaluations are advised. Biodegradability testing showed a consistent degradation trend, with full disintegration extrapolated to occur around 13 weeks under natural soil conditions. This study offers exploratory insight into the development of functional and biodegradable films using biopolymer blends and nanoclay suspensions, highlighting their potential in sustainable food packaging applications. Full article

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

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36 pages, 3088 KiB

Open AccessReview

Underfill: A Review of Reliability Improvement Methods in Electronics Production

by Zbyněk Plachý, Anna Pražanová, Karel Dušek and Attila Géczy

Polymers 2025, 17(16), 2206; https://doi.org/10.3390/polym17162206 - 13 Aug 2025

Abstract

The increasing integration and miniaturization of electronic devices place serious pressure on packaging technologies to ensure long-term reliability. Polymer underfill encapsulation is a key process for reducing thermomechanical stress in modern assemblies. A systematic analysis that frames its diverse methods as solutions to [...] Read more.

The increasing integration and miniaturization of electronic devices place serious pressure on packaging technologies to ensure long-term reliability. Polymer underfill encapsulation is a key process for reducing thermomechanical stress in modern assemblies. A systematic analysis that frames its diverse methods as solutions to the fundamental trade-off between the final polymer composite’s thermomechanical performance and its liquid-state processability is lacking from the literature. The novelty of this review lies in establishing a decision-making framework that connects specific application requirements to the underlying material science and process limitations. This article analyzes and compares different underfill techniques through a systematic literature review, from conventional capillary flow to advanced wafer-level underfills. Our findings show that this core trade-off leads to three distinct strategies: (1) Maximum reliability: This is achieved with highly filled, post-applied composites, offering excellent thermomechanical properties at the cost of slow, viscosity-driven manufacturing speeds. (2) High productivity: This is realized through integrated, pre-applied processes that simplify manufacturing but impose significant constraints on the polymer chemistry and filler content. (3) Targeted reinforcement for board-level packages: At the localized positions applied, ductile polymers often enhance mechanical shock resistance. This review concludes that the optimal underfill choice is not universal but is a complex, application-driven decision balancing the cured material’s performance against the processing demands of the polymer system. Full article

(This article belongs to the Special Issue Polymers for Electronic Device Applications)

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24 pages, 7133 KiB

Open AccessArticle

Critical Adsorption of Polyelectrolytes onto Patchy Particles with a Low-Dielectric Interior

by Dante A. Anhesini, Daniel L. Z. Caetano, Icaro P. Caruso, Andrey G. Cherstvy and Sidney J. de Carvalho

Polymers 2025, 17(16), 2205; https://doi.org/10.3390/polym17162205 - 12 Aug 2025

Abstract

A polyelectrolyte (PE) chain in the vicinity of an oppositely charged surface can exhibit a discontinuous transition from the adsorbed to the desorbed state once the electrostatic attractive interactions are not strong enough to overcome the entropic losses caused by the PE-surface adsorption. [...] Read more.

A polyelectrolyte (PE) chain in the vicinity of an oppositely charged surface can exhibit a discontinuous transition from the adsorbed to the desorbed state once the electrostatic attractive interactions are not strong enough to overcome the entropic losses caused by the PE-surface adsorption. In the context of PE–protein interactions, the heterogeneity of the charge distribution and the effects of a low dielectric permittivity underneath the surface are crucial. Studies of the combined effects of these two properties are very sparse, especially in the spherical geometry; we thus fill this gap here. We study the adsorption of PE chains onto spherical particles with heterogeneously charged surfaces, with the main focus on the critical-adsorption conditions and the effects of a low-dielectric core. Metropolis Monte Carlo simulations are employed, with the PE exploring the phase-space around the binding particle in the canonical ensemble. Two adsorption–desorption transitions are observed when the particle possesses a net charge of the same sign as that of the PE, resulting in nonmonotonic behavior of the critical charge density required for the PE–particle electrostatically driven adsorption. An increased affinity between the PEs and low-dielectric particles with variable heterogeneous charge distributions is observed, in contrast to the behavior detected for homogeneous low-dielectric particles. This higher affinity occurs when the Debye screening length in the solution becomes comparable to the dimensions of a patch of the opposite sign to the PE. A number of real-life applications of the considered PE–particle system is presented in the discussion, in particular regarding the properties of the complex formation between various PEs and globular proteins featuring a dipolar-type distribution of electric charges on their surfaces, such as insulin and bovine serum albumin. Full article

(This article belongs to the Special Issue Theoretical and Computational Polymers Science: Physics, Chemistry and Biology)

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16 pages, 7610 KiB

Open AccessArticle

Interfacial Engineering of BiVO₄ Immobilized on Sodium Alginate Aerogels Enable Synergistic Photocatalytic-Peroxymonosulfate Degradation of Rhodamine B

by Weidi Zhang, Tiantian Zhou and Jianhao Qiu

Polymers 2025, 17(16), 2204; https://doi.org/10.3390/polym17162204 - 12 Aug 2025

Abstract

The practical application of powdered photocatalysts is significantly hindered by challenges in recyclability and structural instability. This work proposes a sustainable immobilization strategy by integrating BiVO₄ nanoparticles into a sodium alginate (SA) aerogel scaffold through a facile freeze-drying approach. The abundant hydroxyl/carboxyl [...] Read more.

The practical application of powdered photocatalysts is significantly hindered by challenges in recyclability and structural instability. This work proposes a sustainable immobilization strategy by integrating BiVO₄ nanoparticles into a sodium alginate (SA) aerogel scaffold through a facile freeze-drying approach. The abundant hydroxyl/carboxyl groups of SA enable uniform dispersion of BiVO₄ within the porous network, while the aerogel architecture enhances light-harvesting efficiency and mass transfer kinetics. Innovatively, peroxymonosulfate (PMS) was introduced to synergistically couple photocatalysis with sulfate radical-based advanced oxidation processes (SR-AOPs), where the photogenerated electrons from BiVO₄ effectively activate PMS to yield high-activity ·SO₄⁻ radicals. The optimized BiVO₄/SA aerogel achieves nearly complete removal of Rhodamine B within 2 h under visible light, which is competitive to pure BiVO₄ powders. In addition, the mechanically robust aerogel exhibits exceptional reusability, retaining ~90% efficiency after five cycles without structural collapse. This work provides a paradigm for designing recyclable photocatalyst carriers with dual oxidation pathways, demonstrating significant potential for industrial wastewater treatment. Full article

(This article belongs to the Special Issue Reduction of Pollution and Carbon Emissions, Functional Polymeric Materials for Adsorption and Catalysis)

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18 pages, 2555 KiB

Open AccessArticle

Development and Characterization of Polymer Blends Based on Polyvinyl Alcohol for Application as Pharmaceutical Dosage Form

by Zarina A. Kenessova, Grigoriy A. Mun, Perizat I. Urkimbayeva, Assel K. Toktabayeva, Raikhan K. Rakhmetullayeva, Bayana B. Yermukhambetova, Zhazira Kenzhebai, Zhuldyzay T. Kurmanova, Mubarak Yermaganbetov and Adilet Zh. Alikulov

Polymers 2025, 17(16), 2203; https://doi.org/10.3390/polym17162203 - 12 Aug 2025

Abstract

Mixtures containing polyvinyl alcohol (PVA) and methylcellulose (MC) were obtained and used to synthesize hydrogels in various ratios of components. The swelling kinetics of the resulting hydrogels were studied, revealing that the equilibrium swelling degree in artificial saliva is nearly twice as high [...] Read more.

Mixtures containing polyvinyl alcohol (PVA) and methylcellulose (MC) were obtained and used to synthesize hydrogels in various ratios of components. The swelling kinetics of the resulting hydrogels were studied, revealing that the equilibrium swelling degree in artificial saliva is nearly twice as high as in water. It was found that increasing the volumetric content of PVA in the mixture leads to a higher swelling degree. The kinetics of active pharmaceutical ingredient (API) sorption and release from the hydrogels were also investigated. It was demonstrated that hydrogels with a higher PVA content exhibit greater sorption capacity; however, the release of the API from such samples occurs at a slower rate. For the first time, the mucoadhesive properties of PVA-MC-based hydrogels were studied. It was established that the PVA-MC hydrogel with a ratio of 6:4 vol.% remained on the surface of the porcine cheek mucosa for two days, the 5.5:4.5 vol.% sample detached after 24 h, and the 5:5 vol.% sample adhered for approximately 10 h. These findings confirm the mucoadhesive potential of the hydrogels and their suitability for buccal drug delivery forms. The synthesized PVA-MC hydrogels are promising for applications in medicine and pharmacology. Full article

(This article belongs to the Special Issue Advances in Synthesis, Testing, and Applications of Natural and Synthetic Polymer Hydrogels)

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33 pages, 2003 KiB

Open AccessReview

Polyacrylamide-Based Solutions: A Comprehensive Review on Nanomaterial Integration, Supramolecular Design, and Sustainable Approaches for Integrated Reservoir Management

by Moamen Hassan Mohamed and Mysara Eissa Mohyaldinn Elhaj

Polymers 2025, 17(16), 2202; https://doi.org/10.3390/polym17162202 - 12 Aug 2025

Abstract

Maximizing hydrocarbon recovery from mature and complex reservoirs is constrained by heterogeneity, sand production, and harsh operational conditions. While polyacrylamide (PAM)-based systems are pivotal in addressing these challenges, a comprehensive synthesis of their transformative evolution and multifunctional capabilities remains overdue. This review critically [...] Read more.

Maximizing hydrocarbon recovery from mature and complex reservoirs is constrained by heterogeneity, sand production, and harsh operational conditions. While polyacrylamide (PAM)-based systems are pivotal in addressing these challenges, a comprehensive synthesis of their transformative evolution and multifunctional capabilities remains overdue. This review critically analyzes advancements in PAM-based materials for enhanced oil recovery (EOR), conformance control, and sand management. We show that nanomaterial integration (e.g., magnetic NPs, nanoclays) significantly augments PAM’s rheological control, thermal and salinity stability, interfacial properties, and wettability alteration. Furthermore, the emergence of supramolecular chemistry has endowed PAM systems with unprecedented resilience, enabling self-healing and adaptive performance under extreme subsurface conditions. The review highlights a crucial paradigm shift towards integrated reservoir management, synergizing these advanced chemical designs with mechanical strategies and leveraging sophisticated monitoring and predictive analytics. Critically, innovations in sustainable and bio-inspired PAM materials offer environmentally responsible solutions with enhanced biodegradability. This synthesis provides a holistic understanding of the state of the art. Despite persistent challenges in scalability and predictability, continually re-engineered PAM systems are positioned as an indispensable and increasingly sustainable cornerstone for future hydrocarbon recovery in the complex energy landscape. Full article

(This article belongs to the Special Issue Polymers in Petroleum Engineering: Enhancing Performance and Sustainability)

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24 pages, 4249 KiB

Open AccessArticle

Biodegradable Antioxidant Composites with Almond Skin Powder

by Irene Gil-Guillén, Idalina Gonçalves, Paula Ferreira, Chelo González-Martínez and Amparo Chiralt

Polymers 2025, 17(16), 2201; https://doi.org/10.3390/polym17162201 - 12 Aug 2025

Abstract

Almond skin (AS) from industrial almond peeling is considered an agri-food waste with adequate composition to obtain composite films for food packaging due to its richness in polysaccharides, proteins, and phenolic compounds. Composite films based on amorphous polylactic acid (PLA) or partially acetylated [...] Read more.

Almond skin (AS) from industrial almond peeling is considered an agri-food waste with adequate composition to obtain composite films for food packaging due to its richness in polysaccharides, proteins, and phenolic compounds. Composite films based on amorphous polylactic acid (PLA) or partially acetylated polyvinilalcohol (PVA) were obtained by melt blending and compression moulding, incorporating different ratios of defatted AS powder (0, 5, 10, and 15 wt.%). The filler was better integrated in the polar PVA matrix, where more interactions were detected with the filler compounds, affecting glass transition and crystallization of the polymer. The AS particles provided the films with the characteristic colour of the powder and strong UV light-blocking effect, while improving the oxygen barrier capacity of both polymeric matrices (24% in PLA with 15% AS and 42% in PVA with 10% AS). The water vapour permeability increased in PLA (by 192% at 15% AS), but decreased in PVA films, especially with low AS content (by 19% with 5% particles). The filler also provided the PLA and PVA films with antioxidant properties due to its phenolic richness, improving the oxygen barrier capacity of the materials and delaying the unsaturated oil oxidation. This was reflected in the lower peroxide and conjugated dienes and trienes values of the sunflower oil packaged in single-dose bags of the different materials. The high oxygen barrier capacity of the PVA bags mainly controlled the preservation of the oil, which made the effect of the antioxidant AS powder less noticeable. Full article

(This article belongs to the Special Issue Polymer Packaging: Sustainable Innovations and Alternatives to Fossil-Based Materials)

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28 pages, 2546 KiB

Open AccessSystematic Review

Sustainable Polymer Composites for Thermal Insulation in Automotive Applications: A Systematic Literature Review

by Dan Dobrotă, Gabriela-Andreea Sava, Andreea-Mihaela Bărbușiu and Gabriel Tiberiu Dobrescu

Polymers 2025, 17(16), 2200; https://doi.org/10.3390/polym17162200 - 12 Aug 2025

Abstract

This systematic literature review explores recent advancements in polymer-based composite materials designed for thermal insulation in automotive applications, with a particular focus on sustainability, performance optimization, and scalability. The methodology follows PRISMA 2020 guidelines and includes a comprehensive bibliometric and thematic analysis of [...] Read more.

This systematic literature review explores recent advancements in polymer-based composite materials designed for thermal insulation in automotive applications, with a particular focus on sustainability, performance optimization, and scalability. The methodology follows PRISMA 2020 guidelines and includes a comprehensive bibliometric and thematic analysis of 229 peer-reviewed articles published over the past 15 years across major databases (Scopus, Web of Science, ScienceDirect, MDPI). The findings are structured around four central research questions addressing (1) the functional role of insulation in automotive systems; (2) criteria for selecting suitable polymer systems; (3) optimization strategies involving nanostructuring, self-healing, and additive manufacturing; and (4) future research directions involving smart polymers, bioinspired architectures, and AI-driven design. Results show that epoxy resins, polyurethane, silicones, and polymeric foams offer distinct advantages depending on the specific application, yet each presents trade-offs between thermal resistance, recyclability, processing complexity, and ecological impact. Comparative evaluation tables and bibliometric mapping (VOSviewer) reveal an emerging research trend toward hybrid systems that combine bio-based matrices with functional nanofillers. The study concludes that no single material system is universally optimal, but rather that tailored solutions integrating performance, sustainability, and cost-effectiveness are essential for next-generation automotive thermal insulation. Full article

(This article belongs to the Special Issue Sustainable Polymer Materials for Industrial Applications)

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21 pages, 7460 KiB

Open AccessArticle

Deciphering the Triple-Peak C-O-C Stretching FTIR Absorbance Consistently Occurring in Semicrystalline PEG

by Theodor Stern

Polymers 2025, 17(16), 2199; https://doi.org/10.3390/polym17162199 - 12 Aug 2025

Abstract

Polyethylene glycol (PEG) is among the most intensively researched and applied polymers, exhibiting a very wide range of industrial, pharmaceutical, and biomedical applications. The strongest and most highly diagnostic absorbance in the FTIR spectrum of PEG and of PEG-containing polyurethanes, is the ether [...] Read more.

Polyethylene glycol (PEG) is among the most intensively researched and applied polymers, exhibiting a very wide range of industrial, pharmaceutical, and biomedical applications. The strongest and most highly diagnostic absorbance in the FTIR spectrum of PEG and of PEG-containing polyurethanes, is the ether C-O-C stretching absorbance, which consistently appears as a triple-peak absorbance in a semicrystalline state. Surprisingly, this phenomenon has very seldom been mentioned or elaborated, and no direct structural diagnostic FTIR assignment has been determined for each component of the triple-peak. The present research conclusively demonstrates that the left-side and right-side components of the triple-peak are assigned to the chain-fold regions and the extended-chain regions of the crystallized chains, respectively, while the strong-wide central component is assigned to the randomly oriented chains in the amorphous phase of the semicrystalline PEG. The present demonstration was facilitated via the synthesis of a highly oriented fibrillar polyurethane block-copolymer, exclusively containing extended-chain-crystallized PEG soft-segments, obtained through dense hard-segment crosslinking under vigorous unidirectional shear-stress continuously applied during the synthesis. The present research results enable us to directly relate the FTIR spectra of PEG and block copolymers synthesized thereof, to their crystallization mechanisms and chain conformations, thus facilitating the development of improved industrial processing methods. Full article

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

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32 pages, 5766 KiB

Open AccessReview

Carbon Nanohorns and Their Nanohybrid/Nanocomposites as Sensing Layers for Humidity Sensors—A Review

by Bogdan-Catalin Serban, Octavian Buiu, Marius Bumbac, Niculae Dumbrăvescu, Mihai Brezeanu, Ursăchescu Matei-Gabriel, Vlad Diaconescu, Maria Ruxandra Sălăgean and Cornel Cobianu

Polymers 2025, 17(16), 2198; https://doi.org/10.3390/polym17162198 - 12 Aug 2025

Abstract

Carbon nanohorns (CNHs), along with their nanocomposites and nanohybrids, have shown significant potential for humidity (RH) monitoring at room temperature (RT) due to their exceptional physicochemical and electronic properties, such as high surface area, tunable porosity, and stability in nanocomposites. Resistive sensors incorporating [...] Read more.

Carbon nanohorns (CNHs), along with their nanocomposites and nanohybrids, have shown significant potential for humidity (RH) monitoring at room temperature (RT) due to their exceptional physicochemical and electronic properties, such as high surface area, tunable porosity, and stability in nanocomposites. Resistive sensors incorporating CNHs have demonstrated superior sensitivity compared to traditional carbon nanomaterials, such as carbon nanotubes and graphene derivatives, particularly in specific RH ranges. This review highlights recent advancements in CNH-based resistive RH sensors, discussing effective synthesis methods (e.g., arc discharge and laser ablation) and functionalization strategies, such as the incorporation of hydrophilic polymers or inorganic fillers like graphene oxide (GO) and metal oxides, which enhance sensitivity and stability. The inclusion of fillers, guided by Pearson’s Hard–Soft Acid–Base (HSAB) theory, enables tuning of CNH-based sensing layers for optimal interaction with water molecules. CNH-based nanocomposites exhibit competitive response and recovery times, making them strong candidates for commercial sensor applications. However, challenges remain, such as optimizing materials for operation across the full 0–100% RH range. This review concludes with proposed research directions to further enhance the adoption and utility of CNHs in sensing applications. Full article

(This article belongs to the Special Issue New Polymeric Nanomaterials: Optimization and Application in the Field of Environmental Sensors)

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19 pages, 1355 KiB

Open AccessArticle

Exploring the Thermal Degradation of Bakelite: Non-Isothermal Kinetic Modeling, Thermodynamic Insights, and Evolved Gas Analysis via Integrated In Situ TGA/MS and TGA/FT-IR Techniques

by Gamzenur Özsin

Polymers 2025, 17(16), 2197; https://doi.org/10.3390/polym17162197 - 12 Aug 2025

Abstract

Thermogravimetric analysis (TGA) is a key technique for evaluating the kinetics and thermodynamics of thermal degradation, providing essential data for material assessment and system design. When coupled with Fourier-transform infrared (FT-IR) spectroscopy or mass spectroscopy (MS), it enables the identification of evolved gases [...] Read more.

Thermogravimetric analysis (TGA) is a key technique for evaluating the kinetics and thermodynamics of thermal degradation, providing essential data for material assessment and system design. When coupled with Fourier-transform infrared (FT-IR) spectroscopy or mass spectroscopy (MS), it enables the identification of evolved gases and correlates mass loss with specific chemical species, offering detailed insight into decomposition mechanisms. In this study, TGA was coupled with FT-IR and MS to investigate the thermal degradation behavior of Bakelite, with the aim of evaluating its kinetic and thermodynamic parameters under non-isothermal conditions, identifying evolved volatile compounds, and elucidating the degradation process. The results showed that higher heating rates led to increased decomposition temperatures and broader dTG peaks due to thermal lag effects. The degradation proceeded in multiple stages between 220 °C and 860 °C, ultimately yielding a carbonaceous residue. The activation energy increased with conversion, particularly beyond 0.5, indicating a greater energy requirement as degradation progressed. Peak values at conversion degrees of 0.8–0.9 suggested enhanced thermal stability or changes in the dominant reaction mechanism. Detailed kinetic analysis revealed complex decomposition pathways with variable activation energies and a pronounced kinetic compensation effect. Thermodynamic analysis confirmed the endothermic nature of the process, with increasing energy demand and non-spontaneous degradation of the resulting char. TGA/FT-IR and TGA/MS analyses identified the release of several compounds, including CO₂, water, formaldehyde, and phenolic derivatives, at distinct stages. This comprehensive understanding of Bakelite’s thermal behavior supports its optimization for high-temperature applications, enhances material reliability and safety, and contributes to sustainable processing and recycling strategies. Full article

(This article belongs to the Special Issue Development in Polymer Recycling)

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