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Polymers, Volume 16, Issue 17 (September-1 2024) – 161 articles

Cover Story (view full-size image): Enhancing the hydrophobicity of polyvinyl alcohol (PVA) for packaging applications remains a challenge. While applying a hydrophobic coating can improve water resistance, the low interaction between the hydrophilic PVA surface and the hydrophobic coating causes aggregations to often occur, preventing proper coating formation. This study aims to achieve dispersibility and uniformity in hydrophobic coatings on PVA, emphasizing the dispersion-improving effect of a carbon quantum dot (CQD) suspension as a solvent. In the proposed model, the small size of CQDs allows for enhanced interactions within the coating suspension and reduces aggregation, resulting in a uniform coating. View this paper
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22 pages, 9683 KiB  
Article
Development of Flexible and Partly Water-Soluble Binder Systems for Metal Fused Filament Fabrication (MF3) of Ti-6Al-4V Parts
by Ralf Eickhoff, Steffen Antusch, Dorit Nötzel, Marcel Probst and Thomas Hanemann
Polymers 2024, 16(17), 2548; https://doi.org/10.3390/polym16172548 - 9 Sep 2024
Abstract
Metal Fused Filament Fabrication provides a simple and cost-efficient way to produce dense metal parts with a homogenous microstructure. However, current limitations include the use of hazardous and expensive organic solvents during debinding for flexible filaments the stiffness of filaments made from partly [...] Read more.
Metal Fused Filament Fabrication provides a simple and cost-efficient way to produce dense metal parts with a homogenous microstructure. However, current limitations include the use of hazardous and expensive organic solvents during debinding for flexible filaments the stiffness of filaments made from partly water-soluble binder systems. In this study, the influence of various additives on different partly water-soluble binder systems, with regard to the flexibility and properties of the final parts, was investigated. Furthermore, a method using dynamic mechanical analysis to quantify the flexibility of filaments was introduced and successfully applied. For the first time, it was possible to produce flexible, partly water-soluble filaments with 60 vol.% solid content, which allowed the 3D printing of complex small and large parts with a high level of detail. After sintering, density values of up to 98.9% of theoretical density were achieved, which is significantly higher than those obtained with existing binder systems. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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22 pages, 3925 KiB  
Article
Chitosan siRNA Nanoparticles Produce Significant Non-Toxic Functional Gene Silencing in Kidney Cortices
by Mohamad-Gabriel Alameh, Ashkan Tavakoli Naeini, Garima Dwivedi, Frederic Lesage, Michael D. Buschmann and Marc Lavertu
Polymers 2024, 16(17), 2547; https://doi.org/10.3390/polym16172547 - 9 Sep 2024
Abstract
Chitosan shows effective nucleic acid delivery. To understand the influence of chitosan’s molecular weight, dose, payload, and hyaluronic acid coating on in vivo toxicity, immune stimulation, biodistribution and efficacy, precisely characterized chitosans were formulated with unmodified or chemically modified siRNA to control for [...] Read more.
Chitosan shows effective nucleic acid delivery. To understand the influence of chitosan’s molecular weight, dose, payload, and hyaluronic acid coating on in vivo toxicity, immune stimulation, biodistribution and efficacy, precisely characterized chitosans were formulated with unmodified or chemically modified siRNA to control for innate immune stimulation. The hemocompatibility, cytokine induction, hematological and serological responses were assessed. Body weight, clinical signs, in vivo biodistribution and functional target knockdown were monitored. Hemolysis was found to be dose- and MW-dependent with the HA coating abrogating hemolysis. Compared to cationic lipid nanoparticles, uncoated and HA-coated chitosan nanoparticles did not induce immune stimulation or hematologic toxicity. Liver and kidney biomarkers remained unchanged with chitosan formulations, while high doses of cationic lipid nanoparticles led to increased transaminase levels and a decrease in body weight. Uncoated and HA-coated nanoparticles accumulated in kidneys with functional knockdown for uncoated chitosan formulations reaching 60%, suggesting potential applications in the treatment of kidney diseases. Full article
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15 pages, 4413 KiB  
Article
Exploring Bio-Based Polyurethane Adhesives for Eco-Friendly Structural Applications: An Experimental and Numerical Study
by Ana M. S. Couto, Catarina S. P. Borges, Shahin Jalali, Beatriz D. Simões, Eduardo A. S. Marques, Ricardo J. C. Carbas, João C. Bordado, Till Vallée and Lucas F. M. da Silva
Polymers 2024, 16(17), 2546; https://doi.org/10.3390/polym16172546 - 9 Sep 2024
Abstract
In response to heightened environmental awareness, various industries, including the civil and automotive sector, are contemplating a shift towards the utilization of more sustainable materials. For adhesive bonding, this necessitates the exploration of materials derived from renewable sources, commonly denoted as bio-adhesives. This [...] Read more.
In response to heightened environmental awareness, various industries, including the civil and automotive sector, are contemplating a shift towards the utilization of more sustainable materials. For adhesive bonding, this necessitates the exploration of materials derived from renewable sources, commonly denoted as bio-adhesives. This study focuses on a bio-adhesive L-joint, which is a commonly employed configuration in the automotive sector for creating bonded structural components with significant bending stiffness. In this investigation, the behavior of joints composed of pine wood and bio-based adhesives was studied. Two distinct configurations were studied, differing solely in the fiber orientation of the wood. The research combined experimental testing and finite element modeling to analyze the strength of the joints and determine their failure mode when subjected to tensile loading conditions. The findings indicate that the configuration of the joint plays a crucial role in its overall performance, with one of the solutions demonstrating higher strength. Additionally, a good degree of agreement was observed between the experimental and numerical analyses for one of the configurations, while the consideration of the maximum principal stress failure predictor (MPSFP) proved to accurately predict the location for crack propagation in both configurations. Full article
(This article belongs to the Special Issue Eco-Friendly Coatings and Adhesive Technology)
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14 pages, 8624 KiB  
Article
Rational Matching of Metal–Organic Frameworks and Polymers in Mixed Matrix Membranes for Efficient Propylene/Propane Separation
by Zijun Yu, Yuxiu Sun, Zhengqing Zhang, Chenxu Geng and Zhihua Qiao
Polymers 2024, 16(17), 2545; https://doi.org/10.3390/polym16172545 - 9 Sep 2024
Abstract
The exploitation of high-performance membranes selective for propylene is important for developing energy-efficient propylene/propane (C3H6/C3H8) separation technologies. Although metal–organic frameworks with a molecular sieving property have been considered promising filler materials in mixed-matrix membranes (MMMs), [...] Read more.
The exploitation of high-performance membranes selective for propylene is important for developing energy-efficient propylene/propane (C3H6/C3H8) separation technologies. Although metal–organic frameworks with a molecular sieving property have been considered promising filler materials in mixed-matrix membranes (MMMs), their use in practical applications has been challenging due to a lack of interface compatibility. Herein, we adopted a surface coordination strategy that involved rationally utilizing carboxyl-functionalized PIM-1 (cPIM) and ZIF-8 to prepare a mixed-matrix membrane for efficient propylene/propane separation. The interfacial coordination between the polymer and the MOF improves their compatibility and eliminates the need for additional modification of the MOF, thereby maximizing the inherent screening performance of the MOF filler. Additionally, the utilization of porous PIM-1 guaranteed the high permeability of the MMMs. The obtained MMMs exhibited excellent separation performance. The 30 wt% ZIF-8/cPIM-1 membrane performed the best, exhibiting a high C3H6 permeability of 1023 Barrer with a moderate C3H6/C3H8 selectivity of 13.97 under 2 bars of pressure. This work presents a method that can feasibly be used for the preparation of defect-free MOF-based MMMs for specific gas separations. Full article
(This article belongs to the Section Polymer Membranes and Films)
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13 pages, 4810 KiB  
Article
Optimization of UV-Curable Polyurethane Acrylate Coatings with Hexagonal Boron Nitride (hBN) for Improved Mechanical and Adhesive Properties
by Vishal Gavande, Shanmugam Mahalingam, Junghwan Kim and Won-Ki Lee
Polymers 2024, 16(17), 2544; https://doi.org/10.3390/polym16172544 - 9 Sep 2024
Abstract
Polymer coatings are widely used in industries for protection, decoration, and specific applications, typically including volatile organic compounds (VOCs) to achieve low viscosity. The growing environmental concerns and the anticipated limits on fossil feedstock have driven the coating industry towards eco-friendly alternatives, with [...] Read more.
Polymer coatings are widely used in industries for protection, decoration, and specific applications, typically including volatile organic compounds (VOCs) to achieve low viscosity. The growing environmental concerns and the anticipated limits on fossil feedstock have driven the coating industry towards eco-friendly alternatives, with UV-curing technology emerging as a promising solution due to its energy efficiency, low-temperature operation, reduced VOC emissions, and high curing speed. Polyurethane acrylates (PUAs) are critical in UV-curable formulations, offering excellent flexibility, impact strength, optical, and adhesion properties. However, UV-cured PUA coatings face limitations in thermal stability and tensile strength, which can be addressed by incorporating fillers. This study investigates the effects of multi-functionalized hexagonal boron nitride (hBN) nanoparticles on the mechanical, thermal, optical, and adhesion properties of UV-cured PUA films and coatings for pre-coated metals. The results demonstrated that incorporating hBN nanoparticles enhanced the mechanical and thermal properties of the nanocomposite films, with optimal performance observed at 0.5% hBN loading. Despite the improved properties, the FTIR spectra indicated that the low concentration of hBN did not produce significant changes, potentially due to the overshadowing signals from the difunctional polyurethane acrylate. Full article
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19 pages, 4866 KiB  
Article
Mechanical Properties of Latex-Modified Cement Stone under Uniaxial and Triaxial Cyclic Loading
by Qizhong Tian, Lianzhi Yang, Jie Zhang and Zhenzhong Xing
Polymers 2024, 16(17), 2543; https://doi.org/10.3390/polym16172543 - 9 Sep 2024
Abstract
During the cyclic injection and extraction process in underground storage wellbores, the cement sheath undergoes loading and unloading stress cycles. In this study, we investigated the mechanical properties of latex-modified cement stone (LMCS), widely used in oil and gas wells, through uniaxial and [...] Read more.
During the cyclic injection and extraction process in underground storage wellbores, the cement sheath undergoes loading and unloading stress cycles. In this study, we investigated the mechanical properties of latex-modified cement stone (LMCS), widely used in oil and gas wells, through uniaxial and triaxial cyclic loading and unloading tests. The aim of the study was to determine the effect of various loading conditions on the compressive strength and stress–strain behavior of LMCS. The results show that the stress–strain curve of LMCS exhibits a hysteresis loop phenomenon, with the loop intervals decreasing throughout the entire cyclic loading and unloading process. As the number of cycles increases, the cumulative plastic strain of the LMCS increases approximately linearly. Under uniaxial cyclic loading and unloading conditions, the elastic modulus tends to stabilize. However, under triaxial conditions, the elastic modulus increases continuously as the number of cycles increases. This result provides data for engineering predictions. Furthermore, a comparison of the uniaxial and triaxial cyclic loading and unloading of LMCS shows that its cumulative plastic strain develops rapidly under uniaxial conditions, while the elastic modulus is larger under triaxial conditions. These findings provide a valuable reference for constructing underground storage wellbores. Full article
(This article belongs to the Section Polymer Processing and Engineering)
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25 pages, 5177 KiB  
Article
From Waste to Styrene–Butadiene (SBR) Reuse: Developing PP/SBR/SEP Mixtures with Carbon Nanotubes for Antistatic Application
by Edson Duarte de Melo Sobrinho, Eduardo da Silva Barbosa Ferreira, Flávio Urbano da Silva, Elieber Barros Bezerra, Renate Maria Ramos Wellen, Edcleide Maria Araújo and Carlos Bruno Barreto Luna
Polymers 2024, 16(17), 2542; https://doi.org/10.3390/polym16172542 - 8 Sep 2024
Abstract
Styrene–butadiene rubber (SBR) waste from the shoe industry was repurposed to produce polypropylene (PP)-based compounds, with the aim of evaluating their antistatic potential. Styrene–ethylene–propylene (SEP) was added as a compatibilizing agent, while carbon nanotubes (MWCNT) were incorporated as a conductive nanofiller. The polymer [...] Read more.
Styrene–butadiene rubber (SBR) waste from the shoe industry was repurposed to produce polypropylene (PP)-based compounds, with the aim of evaluating their antistatic potential. Styrene–ethylene–propylene (SEP) was added as a compatibilizing agent, while carbon nanotubes (MWCNT) were incorporated as a conductive nanofiller. The polymer compounds were processed in an internal mixer, and injection molded. The properties evaluated included torque rheometry, melt flow index (MFI), impact strength, tensile strength, Shore D hardness, electrical conductivity, heat deflection temperature (HDT), and differential scanning calorimetry (DSC), along with scanning electron microscopy (SEM) for morphology analysis. The production of the PP/SBR/SEP (60/30/10 wt%) compound resulted in a ductile material, enhancing impact strength and elongation at break to 161.2% and 165.2%, respectively, compared to pure PP. The addition of SEP improved the compatibility of the PP/SBR system, leading to an increase in the torque curve and a reduction in the MFI. Furthermore, the SBR/SEP combination in PP accelerated the crystallization process and increased the degree of crystallinity, suggesting a nucleating effect. Carbon nanotubes, in concentrations ranging from 0.5 to 2 phr (parts per hundred resin), were added to the PP/SBR/SEP system. Only the PP/SBR/SEP/MWCNT compound with 2 phr of MWCNT was suitable for antistatic applications, exhibiting an electrical conductivity of 4.52 × 10−07 S/cm. This was due to the greater distribution of MWCNT in the PP matrix, as demonstrated by SEM. In addition, remains tough at room temperature, with a 166% increase in impact strength compared to PP. However, there was a reduction in elastic modulus, tensile strength, Shore D hardness, and HDT due to increased flexibility. SBR waste can be reintegrated into the production chain to produce antistatic polymeric compounds, obtaining a tough material at room temperature. Full article
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13 pages, 9286 KiB  
Article
The Biosynthesis of Bacterial Cellulose Composites Accompanied by Spray Feeding of Biomasses
by Jiali Xu, Xiaodi Liu and Qiang Zhang
Polymers 2024, 16(17), 2541; https://doi.org/10.3390/polym16172541 - 8 Sep 2024
Abstract
Bacterial cellulose (BC) is a broadly utilized natural nanofiber produced by microbial fermentation, but its high-cost and low-yield production and limited function still hinder its application. Here, we used the spraying-assisted biosynthesis method to introduce biomass nanofibers along with the nutrient media to [...] Read more.
Bacterial cellulose (BC) is a broadly utilized natural nanofiber produced by microbial fermentation, but its high-cost and low-yield production and limited function still hinder its application. Here, we used the spraying-assisted biosynthesis method to introduce biomass nanofibers along with the nutrient media to the fermenting BC. Biomass nanofibers could be cellulose, chitosan, and others. They entangled with BC nanofibers via intermolecular interactions, including hydrogen binding and electrostatic adsorption, to form uniform BC composites. The BC composites achieved an enhanced yield of ~140 wt% compared with pure BC and displayed similar excellent mechanical properties (Young’s moduli = 0.9–1.4 MPa for wet films and =~6500 MPa for dried films). BC composites also had similar high crystallinity and thermal stability to pure BC. The functional groups of biomasses endowed BC composite additional functions such as antibacterial and dye-adsorption capabilities. Moreover, a high yield and functionalization could be realized simultaneously by feeding functional cellulose nanofibers. This method provides a facile way to produce BC composites with low cost, high yield, and multiple functions. Full article
(This article belongs to the Special Issue Recent Advances in Biodegradable Polymers for Medical Applications)
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12 pages, 8166 KiB  
Article
Paper-Based Fluorescent Sensor for Rapid Multi-Channel Detection of Tetracycline Based on Graphene Quantum Dots Coated with Molecularly Imprinted Polymer
by Linzhe Wang, Jingfang Hu, Wensong Wei, Yu Song, Yansheng Li, Guowei Gao, Chunhui Zhang and Fangting Fu
Polymers 2024, 16(17), 2540; https://doi.org/10.3390/polym16172540 - 8 Sep 2024
Abstract
In this paper, we developed a paper-based fluorescent sensor using functional composite materials composed of graphene quantum dots (GQDs) coated with molecularly imprinted polymers (MIPs) for the selective detection of tetracycline (TC) in water. GQDs, as eco-friendly fluorophores, were chemically grafted onto the [...] Read more.
In this paper, we developed a paper-based fluorescent sensor using functional composite materials composed of graphene quantum dots (GQDs) coated with molecularly imprinted polymers (MIPs) for the selective detection of tetracycline (TC) in water. GQDs, as eco-friendly fluorophores, were chemically grafted onto the surface of paper fibers. MIPs, serving as the recognition element, were then wrapped around the GQDs via precipitation polymerization using 3-aminopropyltriethoxysilane (APTES) as the functional monomer. Optimal parameters such as quantum dot concentration, grafting time, and elution time were examined to assess the sensor’s detection performance. The results revealed that the sensor exhibited a linear response to TC concentrations in the range of 1 to 40 µmol/L, with a limit of detection (LOD) of 0.87 µmol/L. When applied to spiked detection in actual water samples, recoveries ranged from 103.3% to 109.4%. Overall, this paper-based fluorescent sensor (MIPs@GQDs@PAD) shows great potential for portable, multi-channel, and rapid detection of TC in water samples in the future. Full article
(This article belongs to the Special Issue Functional Graphene–Polymer Composites)
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24 pages, 7026 KiB  
Review
A Review of the Establishment of Effective Conductive Pathways of Conductive Polymer Composites and Advances in Electromagnetic Shielding
by Xiaotian Nan, Yi Zhang, Jiahao Shen, Ruimiao Liang, Jiayi Wang, Lan Jia, Xiaojiong Yang, Wenwen Yu and Zhiyi Zhang
Polymers 2024, 16(17), 2539; https://doi.org/10.3390/polym16172539 - 7 Sep 2024
Abstract
The enhancement of the electromagnetic interference shielding efficiency (EMI SE) for conductive polymer composites (CPCs) has garnered increasing attention. The shielding performance is influenced by conductivity, which is dependent on the establishment of effective conductive pathways. In this review, Schelkunoff’s theory on outlining [...] Read more.
The enhancement of the electromagnetic interference shielding efficiency (EMI SE) for conductive polymer composites (CPCs) has garnered increasing attention. The shielding performance is influenced by conductivity, which is dependent on the establishment of effective conductive pathways. In this review, Schelkunoff’s theory on outlining the mechanism of electromagnetic interference shielding was briefly described. Based on the mechanism, factors that influenced the electrical percolation threshold of CPCs were presented and three main kinds of efficient methods were discussed for establishing conductive pathways. Furthermore, examples were explored that highlighted the critical importance of such conductive pathways in attaining optimal shielding performance. Finally, we outlined the prospects for the future direction for advancing CPCs towards a balance of enhanced EMI SE and cost–performance. Full article
(This article belongs to the Special Issue Polymer-Based Composites for EMI Shielding)
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19 pages, 1992 KiB  
Review
Thermal and Catalytic Recycling of Plastics from Waste Electrical and Electronic Equipment—Challenges and Perspectives
by Dimitris S. Achilias, Maria-Anna Charitopoulou and Stefano Vecchio Ciprioti
Polymers 2024, 16(17), 2538; https://doi.org/10.3390/polym16172538 - 7 Sep 2024
Abstract
The amount of end-of-life electrical and electronic devices has been widely increased, globally. This emphasizes how recycling waste electric and electronic equipment (WEEE) is essential in order to reduce the amount of WEEE that is disposed of directly in the environment. Plastics account [...] Read more.
The amount of end-of-life electrical and electronic devices has been widely increased, globally. This emphasizes how recycling waste electric and electronic equipment (WEEE) is essential in order to reduce the amount of WEEE that is disposed of directly in the environment. Plastics account for a big percentage in WEEE, almost 20%. As a result, the application of recycling methods on plastics gathered from WEEE is of great importance since, in this way, landfill disposal can be reduced. Nevertheless, despite the advantages, there are a lot of difficulties, such as the variety of different plastics present in the plastic mix and the existence of various additives in the plastic parts, for instance, brominated flame retardants that need special attention during their treatments, which restricts their wide application. Considering all these, this review aims to provide readers with all the current techniques and perspectives that are available for both the thermal and the catalytic recycling of plastics retrieved from WEEE. Apart from the up-to-date information on the recycling methods, in this review, emphasis is also given on the advantages each method offers and also on the difficulties and the limitations that may prevent them from being applied on a large scale. Current challenges are critically examined, including the use of mechanical or thermo-chemical recycling, the treatment of individual polymers or polymer blends and the separation of harmful additives before recycling or not. Finally, emerging technologies are briefly discussed. Full article
(This article belongs to the Section Circular and Green Polymer Science)
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14 pages, 7121 KiB  
Article
Recognition and Characterization of Nanoscale Phases: Modulus Mapping of Asphalt Film in Pavement Mixture Cores
by Ming Wang, Yuxuan Wang, Jingxuan Guo, Chengwei Xing, Lingyun Zou and Shuaituan Tian
Polymers 2024, 16(17), 2537; https://doi.org/10.3390/polym16172537 - 7 Sep 2024
Abstract
The objective of this study is to recognize and characterize the nanoscale phase modulus mapping of the asphalt film in pavement mixture cores using atomic force microscopy quantitative nanomechanical technology. The pavement core samples from the upper and middle layers of four highways [...] Read more.
The objective of this study is to recognize and characterize the nanoscale phase modulus mapping of the asphalt film in pavement mixture cores using atomic force microscopy quantitative nanomechanical technology. The pavement core samples from the upper and middle layers of four highways and laboratory samples were taken as the research object. The phase modulus–macro property correlation of recovered asphalt was analyzed using mathematical statistics. The results showed that the pavement core samples had more significant multi-phase and diversified phase characteristics compared to lab samples. This indicated that the asphalt in the pavement core had an obvious phase separation phenomenon due to aging. The phase modulus of each sample was distributed across a relatively wide numerical range, and there were also many numerical points with large fluctuations. Especially for the mixture sample containing SBS (Styrene-Butadiene-Styrene)-modified asphalt, the phase modulus distribution mappings presented a multi-peak phenomenon. Hence, considering the distribution characteristics of the data, the box plot method was introduced. Compared with quantified results from laboratory samples, the phase modulus of SBS-modified asphalt increased by 0.96 times, 1.18 times and 1.15 times, and that of base asphalt increased by 0.59 times, 0.56 times, 0.42 times, 1.24 times and 0.39 times, respectively. This indicates that the aging degree of asphalt in the upper layer was generally greater than that of the asphalt in the middle layer and that there was an aging gradient in the direction of pavement depth. All points were within the 95% confidence band in terms of correlation fitting, indicating a better fitting effect between phase modulus and complex shear modulus, as well as between phase modulus and penetration. This research provides innovative ideas for future multi-scale numerical simulation and cross-scale performance model development of asphalt binders. Full article
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24 pages, 2236 KiB  
Review
Biodegradable Polymeric Nanoparticle-Based Drug Delivery Systems: Comprehensive Overview, Perspectives and Challenges
by Małgorzata Geszke-Moritz and Michał Moritz
Polymers 2024, 16(17), 2536; https://doi.org/10.3390/polym16172536 - 7 Sep 2024
Abstract
In the last few decades, there has been a growing interest in the use of biodegradable polymeric nanoparticles (BPNPs) as the carriers for various therapeutic agents in drug delivery systems. BPNPs have the potential to improve the efficacy of numerous active agents by [...] Read more.
In the last few decades, there has been a growing interest in the use of biodegradable polymeric nanoparticles (BPNPs) as the carriers for various therapeutic agents in drug delivery systems. BPNPs have the potential to improve the efficacy of numerous active agents by facilitating targeted delivery to a desired site in the body. Biodegradable polymers are especially promising nanocarriers for therapeutic substances characterized by poor solubility, instability, rapid metabolism, and rapid system elimination. Such molecules can be efficiently encapsulated and subsequently released from nanoparticles, which greatly improves their stability and bioavailability. Biopolymers seem to be the most suitable candidates to be used as the nanocarriers in various delivery platforms, especially due to their biocompatibility and biodegradability. Other unique properties of the polymeric nanocarriers include low cost, flexibility, stability, minimal side effects, low toxicity, good entrapment potential, and long-term and controlled drug release. An overview summarizing the research results from the last years in the field of the successful fabrication of BPNPs loaded with various therapeutic agents is provided. The possible challenges involving nanoparticle stability under physiological conditions and the possibility of scaling up production while maintaining quality, as well as the future possibilities of employing BPNPs, are also reviewed. Full article
(This article belongs to the Special Issue Advanced Biodegradable Polymers for Drug Delivery)
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14 pages, 11748 KiB  
Article
Crack-Based Composite Flexible Sensor with Superhydrophobicity to Detect Strain and Vibration
by Yazhou Zhang, Huansheng Wu, Linpeng Liu, Yang Yang, Changchao Zhang and Ji’an Duan
Polymers 2024, 16(17), 2535; https://doi.org/10.3390/polym16172535 - 7 Sep 2024
Abstract
Vibration sensors are widely applied in the detection of faults and analysis of operational states in engineering machinery and equipment. However, commercial vibration sensors with a feature of high hardness hinder their usage in some practical applications where the measured objects have irregular [...] Read more.
Vibration sensors are widely applied in the detection of faults and analysis of operational states in engineering machinery and equipment. However, commercial vibration sensors with a feature of high hardness hinder their usage in some practical applications where the measured objects have irregular surfaces that are difficult to install. Moreover, as the operating environments of machinery become increasingly complex, there is a growing demand for sensors capable of working in wet and humid conditions. Here, we present a flexible, superhydrophobic vibration sensor with parallel microcracks. The sensor is fabricated using a femtosecond laser direct writing ablation strategy to create the parallel cracks on a PDMS film, followed by spray-coating with a conductive ink composed of MWCNTs, CB, and PDMS. The results demonstrate that the developed flexible sensor exhibits a high-frequency response of up to 2000 Hz, a high acceleration response of up to 100 m/s2, a water contact angle as high as 159.61°, and a linearity of 0.9812 between the voltage signal and acceleration. The results indicate that the sensor can be employed for underwater vibration, sound recognition, and vibration monitoring in fields such as shield cutters, holding significant potential for mechanical equipment vibration monitoring and speech-based human–machine interaction. Full article
(This article belongs to the Section Polymer Composites and Nanocomposites)
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19 pages, 6954 KiB  
Article
Prediction Accuracy of Hyperelastic Material Models for Rubber Bumper under Compressive Load
by Dávid Huri
Polymers 2024, 16(17), 2534; https://doi.org/10.3390/polym16172534 - 7 Sep 2024
Abstract
Different hyperelastic material models (Mooney-Rivlin, Yeoh, Gent, Arruda-Boyce and Ogden) are able to estimate Treloar’s test data series containing uniaxial and biaxial tension and pure shear stress-strain characteristics of rubber. If the rubber behaviour is only determined for the specific load of the [...] Read more.
Different hyperelastic material models (Mooney-Rivlin, Yeoh, Gent, Arruda-Boyce and Ogden) are able to estimate Treloar’s test data series containing uniaxial and biaxial tension and pure shear stress-strain characteristics of rubber. If the rubber behaviour is only determined for the specific load of the product, which, in the case of rubber bumpers, is the compression, the time needed for the laboratory test can be significantly decreased. The stress-strain characteristics of the uniaxial compression test of rubber samples were used to fit hyperelastic material models. Laboratory and numerical tests of a rubber bumper with a given compound and complex geometry were used to determine the accuracy of the material models. Designing rubber products requires special consideration of the numerical discretization process due to the nonlinear behaviours (material nonlinearity, large deformation, connections, etc.). Modelling considerations were presented for the finite element analysis of the rubber bumper. The results showed that if only uniaxial compression test data are available for the curve fitting of the material model, the Yeoh model performs the best in predicting the rubber product material response under compressive load and complex strain state. Full article
(This article belongs to the Special Issue Mechanical Behaviors and Properties of Polymer Materials)
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13 pages, 4481 KiB  
Article
Orientation Control of Perfluorosulfonic Acid Films via Addition of 1,2,4-Triazole during Casting
by Tatsuya Miyajima, Susumu Saito, Takumi Okuyama, Satoshi Matsushita, Tetsuji Shimohira and Go Matsuba
Polymers 2024, 16(17), 2533; https://doi.org/10.3390/polym16172533 - 7 Sep 2024
Abstract
Perfluorosulfonic acid (PFSA) polymers are used as electrolyte membranes in polymer electrolyte fuel cells. To investigate the effect on proton conductivity through structural orientation control, we added 1,2,4-triazole to PFSA films during casting to impart anisotropy to the ion-cluster structure of the films. [...] Read more.
Perfluorosulfonic acid (PFSA) polymers are used as electrolyte membranes in polymer electrolyte fuel cells. To investigate the effect on proton conductivity through structural orientation control, we added 1,2,4-triazole to PFSA films during casting to impart anisotropy to the ion-cluster structure of the films. The proton conductivities of the films were found to be high in the film-surface direction and low in the film-thickness direction. Structural analysis using small-angle X-ray scattering suggested that the anisotropy in proton conductivity was due to anisotropy in the ion-cluster structure, which in turn was attributed to the formation of a phase-separated structure via strong bonding between sulfonic acid groups and 1,2,4-triazole during cast film formation and the surface segregation of fluorine. We expect the findings of this study to aid in the fabrication of PFSA films with controlled ion clusters. Full article
(This article belongs to the Special Issue Advances in High-Performance Polymer Materials)
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22 pages, 13362 KiB  
Article
Bio-Innovative Modification of Poly(Ethylene Terephthalate) Fabric Using Enzymes and Chitosan
by Ivana Čorak, Anita Tarbuk, Sandra Flinčec Grgac and Tihana Dekanić
Polymers 2024, 16(17), 2532; https://doi.org/10.3390/polym16172532 - 7 Sep 2024
Abstract
This article investigates the activation of surface groups of poly(ethylene terephthalate) (PET) fibers in woven fabric by hydrolysis and their functionalization with chitosan. Two types of hydrolysis were performed—alkaline and enzymatic. The alkaline hydrolysis was performed in a more sustainable process at reduced [...] Read more.
This article investigates the activation of surface groups of poly(ethylene terephthalate) (PET) fibers in woven fabric by hydrolysis and their functionalization with chitosan. Two types of hydrolysis were performed—alkaline and enzymatic. The alkaline hydrolysis was performed in a more sustainable process at reduced temperature and time (80 °C, 10 min) with the addition of the cationic surfactant hexadecyltrimethylammonium chloride as an accelerator. The enzymatic hydrolysis was performed using Amano Lipase A from Aspergillus niger (2 g/L enzyme, 60 °C, 60 min, pH 9). The surface of the PET fabric was functionalized with the homogenized gel of biopolymer chitosan using a pad–dry–cure process. The durability of functionalization was tested after the first and tenth washing cycle of a modified industrial washing process according to ISO 15797:2017, in which the temperature was lowered from 75 °C to 50 °C, and ε-(phthalimido) peroxyhexanoic acid (PAP) was used as an environmentally friendly agent for chemical bleaching and disinfection. The influence of the above treatments was analyzed by weight loss, tensile properties, horizontal wicking, the FTIR-ATR technique, zeta potential measurement and SEM micrographs. The results indicate better hydrophilicity and effectiveness of both types of hydrolysis, but enzymatic hydrolysis is more environmentally friendly and favorable. In addition, alkaline hydrolysis led to a 20% reduction in tensile properties, while the action of the enzyme resulted in a change of only 2%. The presence of chitosan on polyester fibers after repeated washing was confirmed on both fabrics by zeta potential and SEM micrographs. However, functionalization with chitosan on the enzymatically bioactivated surface showed better durability after 10 washing cycles than the alkaline-hydrolyzed one. The antibacterial activity of such a bio-innovative modified PET fabric is kept after the first and tenth washing cycles. In addition, applied processes can be easily introduced to any textile factory. Full article
(This article belongs to the Section Biobased and Biodegradable Polymers)
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22 pages, 21751 KiB  
Article
Study of the Reinforcing Effect and Antibacterial Activity of Edible Films Based on a Mixture of Chitosan/Cassava Starch Filled with Bentonite Particles with Intercalated Ginger Essential Oil
by David Castro, Aleksandr Podshivalov, Alina Ponomareva and Anton Zhilenkov
Polymers 2024, 16(17), 2531; https://doi.org/10.3390/polym16172531 - 6 Sep 2024
Abstract
Edible films based on biopolymers are used to protect food from adverse environmental factors. However, their ample use may be hindered by some challenges to their mechanical and antimicrobial properties. Despite this, in most cases, increasing their mechanical properties and antibacterial activity remains [...] Read more.
Edible films based on biopolymers are used to protect food from adverse environmental factors. However, their ample use may be hindered by some challenges to their mechanical and antimicrobial properties. Despite this, in most cases, increasing their mechanical properties and antibacterial activity remains a relevant challenge. To solve this problem, a possible option is to fill the biopolymer matrix of films with a functional filler that combines high reinforcing and antibacterial properties. In this work, biocomposite films based on a mixture of chitosan and cassava starch were filled with a hybrid filler in the form of bentonite clay particles loaded with ginger essential oil (GEO) in their structure with varied concentrations. For this purpose, GEO components were intercalated into bentonite clay interlayer space using a mechanical capture approach without using surface-active and toxic agents. The structure and loading efficiency of the essential oil in the obtained hybrid filler were analyzed by lyophilization and laser analysis of dispersions, ATR-FTIR spectroscopy, thermogravimetry, and X-ray diffraction analysis. The filled biocomposite films were analyzed using ATR-FTIR spectroscopy, optical and scanning electron spectroscopy, energy dispersive spectroscopy, mechanical analysis under tension, and the disk diffusion method for antibacterial activity. The results demonstrated that the tensile strength, Young’s modulus, elongation at the break, and the antibacterial effect of the films increased by 40%, 19%, 44%, and 23%, respectively, compared to unfilled film when the filler concentration was 0.5–1 wt.%. Full article
(This article belongs to the Special Issue Biomaterials Modification, Characterization and Applications)
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26 pages, 8179 KiB  
Article
Unraveling the Effect of Strain Rate and Temperature on the Heterogeneous Mechanical Behavior of Polymer Nanocomposites via Atomistic Simulations and Continuum Models
by Ali A. Youssef, Hilal Reda and Vagelis Harmandaris
Polymers 2024, 16(17), 2530; https://doi.org/10.3390/polym16172530 - 6 Sep 2024
Abstract
Polymer nanocomposites are characterized by heterogeneous mechanical behavior and performance, which is mainly controlled by the interaction between the nanofiller and the polymer matrix. Optimizing their material performance in engineering applications requires understanding how both the temperature and strain rate of the applied [...] Read more.
Polymer nanocomposites are characterized by heterogeneous mechanical behavior and performance, which is mainly controlled by the interaction between the nanofiller and the polymer matrix. Optimizing their material performance in engineering applications requires understanding how both the temperature and strain rate of the applied deformation affect mechanical properties. This work investigates the effect of strain rate and temperature on the mechanical properties of poly(ethylene oxide)/silica (PEO/SiO2) nanocomposites, revealing their behavior in both the melt and glassy states, via atomistic molecular dynamics simulations and continuum models. In the glassy state, the results indicate that Young’s modulus increases by up to 99.7% as the strain rate rises from 1.0 × 10−7 fs−1 to 1.0 × 10−4 fs−1, while Poisson’s ratio decreases by up to 39.8% over the same range. These effects become even more pronounced in the melt state. Conversely, higher temperatures lead to an opposing trend. A local, per-atom analysis of stress and strain fields reveals broader variability in the local strain of the PEO/SiO2 nanocomposites as temperature increases and/or the deformation rate decreases. Both interphase and matrix regions lose rigidity at higher temperatures and lower strain rates, blurring their distinctiveness. The results of the atomistic simulations concerning the elastic modulus and Poisson’s ratio are in good agreement with the predictions of the Richeton–Ji model. Additionally, these findings can be leveraged to design advanced polymer composites with tailored mechanical properties and could optimize structural components by enhancing their performance under diverse engineering conditions. Full article
(This article belongs to the Special Issue Rheological Properties of Polymers and Polymer Composites)
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19 pages, 5640 KiB  
Article
Tribological Performance of Additive Manufactured PLA-Based Parts
by Moises Batista, Irene Del Sol, Álvaro Gómez-Parra and Juan Manuel Vazquez-Martinez
Polymers 2024, 16(17), 2529; https://doi.org/10.3390/polym16172529 - 6 Sep 2024
Abstract
Polymer additive manufacturing has advanced from prototyping to producing essential parts with improved precision and versatility. Despite challenges like surface finish and wear resistance, new materials and metallic reinforcements in polymers have expanded its applications, enabling stronger, more durable parts for demanding industries [...] Read more.
Polymer additive manufacturing has advanced from prototyping to producing essential parts with improved precision and versatility. Despite challenges like surface finish and wear resistance, new materials and metallic reinforcements in polymers have expanded its applications, enabling stronger, more durable parts for demanding industries like aerospace and structural engineering. This research investigates the tribological behaviour of FFF surfaces by integrating copper and aluminium reinforcement particles into a PLA (polylactic acid) matrix. Pin-on-disc tests were conducted to evaluate friction coefficients and wear rates. Statistical analysis was performed to study the correlation of the main process variables. The results confirmed that reinforced materials offer interesting characteristics despite their complex use, with the roughness of the fabricated parts increasing by more than 300%. This leads to an increase in the coefficient of friction, which is related to the variation in the material’s mechanical properties, as the hardness increases by more than 75% for materials reinforced with Al. Despite this, their performance is more stable, and the volume of material lost due to wear is reduced by half. These results highlight the potential of reinforced polymers to improve the performance and durability of components manufactured through additive processes. Full article
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19 pages, 3986 KiB  
Article
Molecularly Imprinted Polypyrrole-Modified Screen-Printed Electrode for Dopamine Determination
by Daniele Merli, Alessandra Cutaia, Ines Hallulli, Alessandra Bonanni and Giancarla Alberti
Polymers 2024, 16(17), 2528; https://doi.org/10.3390/polym16172528 - 6 Sep 2024
Abstract
This paper introduces a quantitative method for dopamine determination. The method is based on a molecularly imprinted polypyrrole (e-MIP)-modified screen-printed electrode, with differential pulse voltammetry (DPV) as the chosen measurement technique. The dopamine molecules are efficiently entrapped in the polymeric film, creating recognition [...] Read more.
This paper introduces a quantitative method for dopamine determination. The method is based on a molecularly imprinted polypyrrole (e-MIP)-modified screen-printed electrode, with differential pulse voltammetry (DPV) as the chosen measurement technique. The dopamine molecules are efficiently entrapped in the polymeric film, creating recognition cavities. A comparison with bare and non-imprinted polypyrrole-modified electrodes clearly demonstrates the superior sensitivity, selectivity, and reproducibility of the e-MIP-based one; indeed, a sensitivity of 0.078 µA µM−1, a detection limit (LOD) of 0.8 µM, a linear range between 0.8 and 45 µM and a dynamic range of up to 350 µM are achieved. The method was successfully tested on fortified synthetic and human urine samples to underline its applicability as a screening method for biomedical tests. Full article
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16 pages, 9081 KiB  
Article
The Influence of Mixing Speed on the Physicomechanical Parameters of Polyaddition Poly(dimethylsiloxanes) with Fillers
by Ewelina Chmielnicka, Małgorzata Szymiczek and Błażej Chmielnicki
Polymers 2024, 16(17), 2527; https://doi.org/10.3390/polym16172527 - 6 Sep 2024
Abstract
In this article, we present an analysis of the properties of polyaddition poly(dimethylsiloxanes) (PDMS) and their potential applications after modification. The focus is on understanding how different fillers and mixing speeds affect the mechanical and electrical properties of PDMS, as well as the [...] Read more.
In this article, we present an analysis of the properties of polyaddition poly(dimethylsiloxanes) (PDMS) and their potential applications after modification. The focus is on understanding how different fillers and mixing speeds affect the mechanical and electrical properties of PDMS, as well as the benefits and challenges associated with these modifications. Additionally, the prospects for future development of PDMS-based technologies, which could bring significant innovations in various industrial fields, are discussed. Full article
(This article belongs to the Section Polymer Composites and Nanocomposites)
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40 pages, 14083 KiB  
Review
Wound Dressing with Electrospun Core-Shell Nanofibers: From Material Selection to Synthesis
by Nariman Rajabifar, Amir Rostami, Shahnoosh Afshar, Pezhman Mosallanezhad, Payam Zarrintaj, Mohsen Shahrousvand and Hossein Nazockdast
Polymers 2024, 16(17), 2526; https://doi.org/10.3390/polym16172526 - 5 Sep 2024
Abstract
Skin, the largest organ of the human body, accounts for protecting against external injuries and pathogens. Despite possessing inherent self-regeneration capabilities, the repair of skin lesions is a complex and time-consuming process yet vital to preserving its critical physiological functions. The dominant treatment [...] Read more.
Skin, the largest organ of the human body, accounts for protecting against external injuries and pathogens. Despite possessing inherent self-regeneration capabilities, the repair of skin lesions is a complex and time-consuming process yet vital to preserving its critical physiological functions. The dominant treatment involves the application of a dressing to protect the wound, mitigate the risk of infection, and decrease the likelihood of secondary injuries. Pursuing solutions for accelerating wound healing has resulted in groundbreaking advancements in materials science, from hydrogels and hydrocolloids to foams and micro-/nanofibers. Noting the convenience and flexibility in design, nanofibers merit a high surface-area-to-volume ratio, controlled release of therapeutics, mimicking of the extracellular matrix, and excellent mechanical properties. Core-shell nanofibers bring even further prospects to the realm of wound dressings upon separate compartments with independent functionality, adapted release profiles of bioactive agents, and better moisture management. In this review, we highlight core-shell nanofibers for wound dressing applications featuring a survey on common materials and synthesis methods. Our discussion embodies the wound healing process, optimal wound dressing characteristics, the current organic and inorganic material repertoire for multifunctional core-shell nanofibers, and common techniques to fabricate proper coaxial structures. We also provide an overview of antibacterial nanomaterials with an emphasis on their crystalline structures, properties, and functions. We conclude with an outlook for the potential offered by core-shell nanofibers toward a more advanced design for effective wound healing. Full article
(This article belongs to the Special Issue Electrospun Nanofibers: Current Advances and Future Perspective)
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11 pages, 3215 KiB  
Article
Comparison of Bulk Polymeric Resin Composite and Hybrid Glass Ionomer Cement in Adhesive Class I Dental Restorations: A 3D Finite Element Analysis
by Alessandro E. di Lauro, Stefano Ciaramella, João P. Mendes Tribst, Angelo Aliberti and Pietro Ausiello
Polymers 2024, 16(17), 2525; https://doi.org/10.3390/polym16172525 - 5 Sep 2024
Abstract
This study aimed to investigate the mechanical behavior of resin composites and hybrid glass ionomer cement in class I adhesive dental restorations under loading and shrinkage conditions. Three CAD models of a mandibular first molar with class I cavities were created and restored [...] Read more.
This study aimed to investigate the mechanical behavior of resin composites and hybrid glass ionomer cement in class I adhesive dental restorations under loading and shrinkage conditions. Three CAD models of a mandibular first molar with class I cavities were created and restored with different techniques: a bi-layer of Equia Forte HT with Filtek One Bulk Fill Restorative composite (model A), a single layer of adhesive and Filtek One Bulk Fill Restorative (model B), and a single layer of Equia forte HT (model C). Each model was exported to computer-aided engineering software, and 3D finite element models were created. Models A and B exhibited a similar pattern of stress distribution along the enamel–restoration interface, with stress peaks of 12.5 MPa and 14 MPa observed in the enamel tissue. The sound tooth, B, and C models showed a similar trend along the interface between dentine and restoration. A stress peak of about 0.5 MPa was detected in the enamel of both the sound tooth and B models. Model C showed a reduced stress peak of about 1.2 MPa. A significant stress reduction in 4 mm deep class I cavities in lower molars was observed in models where non-shrinking dental filling materials, like the hybrid glass ionomer cement used in model C, were applied. Stress reduction was also achieved in model A, which employed a bi-layer technique with a shrinking polymeric filling material (bulk resin composite). Model C’s performance closely resembled that of a sound tooth. Full article
(This article belongs to the Special Issue Advanced Polymeric Materials for Dental Applications III)
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34 pages, 14745 KiB  
Article
Analysis of Mechanical Properties and Parameter Dependency of Novel, Doubly Re-Entrant Auxetic Honeycomb Structures
by Levente Széles, Richárd Horváth and Lívia Cveticanin
Polymers 2024, 16(17), 2524; https://doi.org/10.3390/polym16172524 - 5 Sep 2024
Abstract
This study proposes a new, doubly re-entrant auxetic unit-cell design that is based on the widely used auxetic honeycomb structure. Our objective was to develop a structure that preserves and enhances the advantages of the auxetic honeycomb while eliminating all negative aspects. The [...] Read more.
This study proposes a new, doubly re-entrant auxetic unit-cell design that is based on the widely used auxetic honeycomb structure. Our objective was to develop a structure that preserves and enhances the advantages of the auxetic honeycomb while eliminating all negative aspects. The doubly re-entrant geometry design aims to enhance the mechanical properties, while eliminating the buckling deformation characteristic of the re-entrant deformation mechanism. The effects of the geometric modification are described and evaluated using two parameters, offset and deg. A series of experiments were conducted on a wide range of parameters based on these two parameters. Specimens were printed via the vat photopolymerization process and were subjected to a compression test. Our aim was to investigate the mechanical properties (energy absorption and compressive force) and the deformation behaviour of these specimens in relation to the relevant parameters. The novel geometry achieved the intended properties, outperforming the original auxetic honeycomb structure. Increasing the offset and deg parameters results in increasing the energy absorption capability (up to 767%) and the maximum compressive force (up to 17 times). The right parameter choice eliminates buckling and results in continuous auxetic behaviour. Finally, the parameter dependency of the deformation behaviour was predicted by analytical approximation as well. Full article
(This article belongs to the Special Issue Polymer-Based Metamaterials and Metastructures)
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17 pages, 3544 KiB  
Article
A Dynamic Mechanical Analysis on the Compatibilization Effect of Two Different Polymer Waste-Based Compatibilizers in the Fifty/Fifty Polypropylene/Polyamide 6 Blend
by Emilia P. Collar and Jesús-María García-Martínez
Polymers 2024, 16(17), 2523; https://doi.org/10.3390/polym16172523 - 5 Sep 2024
Abstract
This study aims to examine the 50/50 polypropylene/polyamide 6 (iPP/PA6) system molded under confined flow conditions, both in its original state and after being modified by two different interfacial agents. This study provides two main insights. Firstly, it focuses on a polymer blend [...] Read more.
This study aims to examine the 50/50 polypropylene/polyamide 6 (iPP/PA6) system molded under confined flow conditions, both in its original state and after being modified by two different interfacial agents. This study provides two main insights. Firstly, it focuses on a polymer blend close to phase inversion. Secondly, it investigates the impact of using two different types of interfacial agents (derived from polymer waste) to enhance the compatibility between iPP and PA6. Dynamic Mechanical Analysis (DMA) has been employed to achieve these objectives. It is important to note that the investigation of the 50/50 iPP/PA6 system is a crucial focus predicted in previous studies, where a series of mechanical properties were evaluated using Box–Wilson design of experiments (DOEs) over the whole compositional range on the iPP/PA6 binary system. Thus, two interfacial modifiers, namely succinic anhydride (SA)-grafted atactic polypropylene with terminal, side, and bridge SA grafts (aPP-SASA) and succinyl-fluoresceine (SF) with bridge succinic anhydride grafting atactic polypropylene (aPP-SFSA), were employed. The authors obtained and characterized these agents. The quantity of these agents used in the blend was identified as a critical coordinate in prior studies conducted by the authors. The processing method used, compression molding under confined conditions, was chosen to minimize any orientation effect on the emerging morphology. All characterization procedures were performed on samples processed by contour machining to retain the blend morphologies as they emerged from the processing stage. Results from WAXS and SAXS synchrotron tests concluded there were no changes in the crystal morphology of the iPP or the PA6 in the blends nor any co-crystallization process throughout the compositional range. These findings, and the long period fits on the PP crystalline phase for the fifty/fifty blends we are discussing, will support the present DMA study. Finally, the efficiency of these interfacial modifiers has been concluded, even in this unfavorable scenario. Full article
(This article belongs to the Special Issue Polymers and the Environment II)
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17 pages, 13994 KiB  
Article
Tailoring Hydrogel Sheet Properties through Co-Monomer Selection in AMPS Copolymer Macromers
by Jinjutha Daengmankhong, Thanyaporn Pinthong, Sudarat Promkrainit, Maytinee Yooyod, Sararat Mahasaranon, Winita Punyodom, Sukunya Ross, Jirapas Jongjitwimol, Brian J. Tighe, Matthew J. Derry, Paul D. Topham and Gareth M. Ross
Polymers 2024, 16(17), 2522; https://doi.org/10.3390/polym16172522 - 5 Sep 2024
Abstract
This study investigates hydrogels based on 2-Acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS) copolymers, incorporating N-hydroxyethyl acrylamide (HEA) and 3-sulfopropyl acrylate potassium salt (SPA). The addition of HEA and SPA is designed to fine-tune the hydrogels’ water absorption and mechanical properties, ultimately enhancing their characteristics [...] Read more.
This study investigates hydrogels based on 2-Acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS) copolymers, incorporating N-hydroxyethyl acrylamide (HEA) and 3-sulfopropyl acrylate potassium salt (SPA). The addition of HEA and SPA is designed to fine-tune the hydrogels’ water absorption and mechanical properties, ultimately enhancing their characteristics and expanding their potential for biomedical applications. A copolymer of AMPS, 2-carboxyethyl acrylate (CEA) combined with methacrylic acid (MAA) as poly(AMPS-stat-CEA-stat-MAA, PACM), was preliminarily synthesized. CEA and MAA were modified with allyl glycidyl ether (AGE) through ring-opening, yielding macromers with pendant allyl groups (PACM-AGE). Copolymers poly(AMPS-stat-HEA-stat-CEA-stat-MAA) (PAHCM) and poly(AMPS-stat-SPA-stat-CEA-stat-MAA) (PASCM) were also synthesized and modified with AGE to produce PAHCM-AGE and PASCM-AGE macromers. These copolymers and macromers were characterized by 1H NMR, FT-IR, and GPC, confirming successful synthesis and functionalization. The macromers were then photocrosslinked into hydrogels and evaluated for swelling, water content, and mechanical properties. The results revealed that the PASCM-AGE hydrogels exhibited superior swelling ratios and water retention, achieving equilibrium water content (~92%) within 30 min. While the mechanical properties of HEA and SPA containing hydrogels show significant differences compared to PACM-AGE hydrogel (tensile strength 2.5 MPa, elongation 47%), HEA containing PAHCM-AGE has a higher tensile strength (5.8 MPa) but lower elongation (19%). In contrast, SPA in the PASCM-AGE hydrogels led to both higher tensile strength (3.7 MPa) and greater elongation (92%), allowing for a broader range of hydrogel properties. An initial study on drug delivery behavior was conducted using PACM-AGE hydrogels loaded with photosensitizers, showing effective absorption, release, and antibacterial activity under light exposure. These AMPS-based macromers with HEA and SPA modifications demonstrate enhanced properties, making them promising for wound management and drug delivery applications. Full article
(This article belongs to the Collection Hydrogels)
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15 pages, 6783 KiB  
Article
Early Biological Response to Poly(ε-Caprolactone)/Alumina-Toughened Zirconia Composites Obtained by 3D Printing for Peri-Implant Application
by Riccardo Pedraza, Alessandro Mosca Balma, Ilaria Roato, Clarissa Orrico, Tullio Genova, Giacomo Baima, Giovanni Nicolao Berta, Andrea Giura, Luigi Ribotta, Donatella Duraccio, Maria Giulia Faga and Federico Mussano
Polymers 2024, 16(17), 2521; https://doi.org/10.3390/polym16172521 - 5 Sep 2024
Abstract
The improvement of the mucosal sealing around the implant represents a challenge, one that prompted research into novel materials. To this purpose, a printable poly(ε-caprolactone) (PCL)-based composite loaded with alumina-toughened zirconia (ATZ) at increasing rates of 10, 20, and 40 wt.% was prepared, [...] Read more.
The improvement of the mucosal sealing around the implant represents a challenge, one that prompted research into novel materials. To this purpose, a printable poly(ε-caprolactone) (PCL)-based composite loaded with alumina-toughened zirconia (ATZ) at increasing rates of 10, 20, and 40 wt.% was prepared, using a solvent casting method with chloroform. Disks were produced by 3D printing; surface roughness, free energy and optical contact angle were measured. Oral fibroblasts (PF) and epithelial cell (SG) tests were utilized to determine the biocompatibility of the materials through cell viability assay and adhesion and spreading evaluations. The highest level of ATZ resulted in an increase in the average roughness (Sa), while the maximum height (Sz) was higher for all composites than that of the unmixed PCL, regardless of their ATZ content. Surface free energy was significantly lower on PCL/ATZ 80/20 and PCL/ATZ 60/40, compared to PCL and PCL/ATZ 90/10. The contact angle was inversely related to the quantity of ATZ in the material. PF grew without variations among the different specimens at 1 and 3 days. After 7 days, PF grew significantly less on PCL/ATZ 60/40 and PCL/ATZ 80/20 compared to unmixed PCL and PCL 90/10. Conversely, ATZ affected and improved the growth of SG. By increasing the filler amount, PF cell adhesion and spreading augmented, while PCL/ATZ 80/20 was the best for SG adhesion. Overall, PCL/ATZ 80/20 emerged as the best composite for both cell types; hence, it is a promising candidate for the manufacture of custom made transmucosal dental implant components. Full article
(This article belongs to the Special Issue Medical Application of Polymer-Based Composites IV)
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18 pages, 4314 KiB  
Article
Toward the Production of Hydroxyapatite/Poly(Ether-Ether-Ketone) (PEEK) Biocomposites: Exploring the Physicochemical, Mechanical, Cytotoxic and Antimicrobial Properties
by Meirilany Rozeno Costa, José Adeilton Carvalho Filho, Carlos Bruno Barreto Luna, Gleydis Manalig Pereira Dantas, Ana Cristina Figueiredo de Melo Costa and Nadja Maria da Silva Oliveira
Polymers 2024, 16(17), 2520; https://doi.org/10.3390/polym16172520 - 5 Sep 2024
Abstract
The development of hydroxyapatite (HAp) and polyether ether ketone (PEEK) biocomposites has been extensively studied for bone repair applications due to the synergistic properties of the involved materials. In this study, we aimed to develop HAp/PEEK biocomposites using high-energy ball milling, with HAp [...] Read more.
The development of hydroxyapatite (HAp) and polyether ether ketone (PEEK) biocomposites has been extensively studied for bone repair applications due to the synergistic properties of the involved materials. In this study, we aimed to develop HAp/PEEK biocomposites using high-energy ball milling, with HAp concentrations (20%, 40%, and 60% w/v) in PEEK, to evaluate their physicochemical, mechanical, cytotoxicity, and antimicrobial properties for potential applications in Tissue Engineering (TE). The biocomposites were characterized by structure, morphology, apparent porosity, diametral compression strength, cytotoxicity, and antimicrobial activity. The study results demonstrated that the HAp/PEEK biocomposites were successfully synthesized. The C2 biocomposite, containing 40% HAp, stood out due to the optimal distribution of HAp particles in the PEEK matrix, resulting in higher compression strength (246 MPa) and a homogeneous microstructure. It exhibited antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, with no cytotoxicity observed. These properties make the C2 biocomposite promising for regenerative medicine applications, combining mechanical strength, bioactivity, and biocompatibility. Full article
(This article belongs to the Special Issue Application and Characterization of Polymer Composites)
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12 pages, 4110 KiB  
Article
Laboratory Evaluation of Geosynthetic Interface Friction under Low Stress
by Paolo Carrubba
Polymers 2024, 16(17), 2519; https://doi.org/10.3390/polym16172519 - 5 Sep 2024
Abstract
In landfill cover, geosynthetic packages are often used to fulfil different and simultaneous functions: drainage, waterproofing, separation, reinforcement, and soil protection. In this regard, various types of geosynthetics are combined in succession to allow for water and biogas drainage and to waterproof, reinforce, [...] Read more.
In landfill cover, geosynthetic packages are often used to fulfil different and simultaneous functions: drainage, waterproofing, separation, reinforcement, and soil protection. In this regard, various types of geosynthetics are combined in succession to allow for water and biogas drainage and to waterproof, reinforce, and provide protection from erosion over the useful lifetime, ranging over many decades if we consider the long phases of disposal, closure, and quiescence of the landfill itself. The creation of the composite cover barrier requires the evaluation of various interfaces’ frictional strength under low contact stresses, both in static and seismic cases. The main purpose of this study is to summarize the results of past laboratory tests carried out on different geosynthetic–geosynthetic and geosynthetic–soil–geosynthetic interfaces using experimental instrumentation developed at the geotechnical laboratory of the University of Padua, which allows for the characterization of the interface geosynthetic friction at low contact stresses. The main aspects highlighted are the kinematic mode of failure, the wearing of the contact surfaces, the presence or absence of interstitial fluid, and, finally, the density level of the granular soil in contact with the geosynthetics. Full article
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