Search Results (625)

pH-responsive indicator films for intelligent food packaging applications are based on the embedding of a natural or synthetic dye in a polymeric substrate, preferably biobased and biodegradable. Although natural colorants like anthocyanins were extensively investigated in this respect, nature-inspired synthetic flavylium compounds could represent an alternative based on their higher stability. In this work, five novel synthetic 4′-aminoflavylium derivatives with different substitution patterns in the benzopyrylium core (compounds 1–5) were synthesized and characterized. Polyvinyl alcohol (PVA), as well as chitosan–PVA and chitosan–starch blends, were used to prepare pH-responsive indicator films having inserted each of the synthesized flavylium dyes or a natural onion peel extract. The PVA films with compounds 1 and 3, and the PVA–chitosan film with compound 1, exhibited antioxidant activity, highlighting their potential for active packaging applications. All indicator films showed pH responsiveness in the range of 2 to 12 and were subsequently tested in contact with the packaging atmosphere or in direct contact with pork and fish meat, at different temperatures (4 °C, 20 °C, and 40 °C) for 24 h to assess their colorimetric response to progressive spoilage. Although the differences were small, the films with the 7-hydroxy-4′-aminoflavylium derivative exhibited the earliest and most intense color change during storage of meat, starting from direct contact at 4 °C for 24 h, being able to identify the initial stages of meat spoilage, while the performance of the dihydroxy-substituted derivative was attenuated by incorporation in polymer matrices. This behavior was comparable to that of onion peel extract, but the synthetic flavylium derivative was more stable. The results can provide new opportunities for intelligent food packaging applications using biopolymer indicator films with 4′-aminoflavylium derivatives. Full article

Background: Pantoprazole is a widely used proton pump inhibitor that is highly unstable under acidic conditions. This limits the performance of conventional formulations and typically requires enteric-coated dosage forms or alternative modified-release approaches. This study reports the development of polymeric matrix mini-tablets designed to protect pantoprazole during gastric exposure and to enable pH-dependent release under intestinal conditions. The formulations combine Eudragit^® S 100, a pH-dependent polymer, with HPMC, a hydrophilic matrix former that modulates drug release through hydration and swelling. Methods: Matrix mini-tablets were prepared by blending pantoprazole with selected excipients at optimised proportions and compressing the blends by direct compression using an eccentric tablet press. Powder blends and mini-tablets were characterised according to pharmacopoeial specifications. Analytical techniques—including High-Performance Liquid Chromatography (HPLC), Differential Scanning Calorimetry (DSC), Fourier-Transform Infrared Absorption Spectroscopy (FT-IR), Powder X-Ray Diffraction (PXRD), and Scanning Electron Microscopy (SEM)—were employed to evaluate drug content uniformity, thermal behaviour, and potential drug–excipient interactions. In vitro dissolution studies were performed under sequential pH conditions, and the release kinetics were analysed using mathematical models. Results: Dissolution testing identified formulations F2 and F6 as providing the most suitable gastro-resistant performance in the acidic stage, together with sustained release up to 24 h. Kinetic modelling supported formulation-dependent release mechanisms, and multivariate analysis (PCA) highlighted relationships between physico-mechanical attributes and drug-release behaviour. Conclusions: The proposed matrix system shows potential as a robust, coating-free platform for the modified delivery of acid-labile drugs using direct compression, simplifying manufacturing. These findings support the rational design of oral modified-release formulations based on polymeric matrices. Full article

A water-rich muscle-equivalent tissue-mimicking phantom within a polymeric matrix was experimentally evaluated through a multimodal characterization methodology to determine whether it reproduces the coupled dielectric–thermal behavior of hydrated biological tissue under exposure to electromagnetic waves. The material was analyzed using thermogravimetric analysis, microwave dielectric spectroscopy from 1.5 to 4.0 GHz, VIS–NIR spectroscopy between 350 and 1200 nm, and terahertz time-domain reflection. The thermogravimetric results confirmed dominant water content, with primary mass loss below 200 °C, establishing hydration as the governing factor of its thermal response. Next, the microwave dielectric measurements show that the phantom exhibits a relative permittivity of 37.4 and an electrical conductivity of 2.4 S/m. On the other hand, the VIS–NIR spectra show smooth broadband absorption with limited spatial variability, and principal component analysis reveals macroscopic optical homogeneity without structural spectral distortion. In the THz regime, strong broadband attenuation characteristic of water-rich matrices is observed, and reflection-mode measurements enable robust assessment of temporal stability through time- and frequency-domain signatures. Finally, a microwave thermal validation demonstrates stable behavior under low-power excitation, whereas under hyperthermia-level irradiation, a significant thermal drift of −3.985 °C/h was reached under non-adiabatic conditions, identifying hydration-mediated moisture redistribution as the principal limitation during prolonged high-power exposure. Collectively, these results demonstrate cross-regime dielectric–thermal consistency while explicitly defining the hydration-driven constraints governing long-term stability, providing a validated reference material for broadband electromagnetic and thermal biomedical experimentation. Full article

The behavior and properties of polymer–resin blends are critical for the design of advanced polymeric systems in a wide range of applications. In this work, we present an atomistic molecular dynamics study of the effects of hydrogenated dicyclopentadiene (H-DCPD) resin on the structural, dynamical, and viscoelastic properties of polymer matrices. Two different systems are examined: linear 1,4-cis polyisoprene (PI) and a four-component styrene–butadiene rubber (SBR) copolymer. The results reveal lower miscibility of H-DCPD resin in PI compared to that in SBR, as evidenced by the formation of resin-rich domains, revealed by the magnitude of local peaks in resin–resin radial distribution functions. Temperature-dependent analysis shows that structural and dynamical properties are most sensitive at ambient conditions (T = 300 K, P = 1 atm), with PI exhibiting significantly reduced molecular mobility due to its proximity to the glass transition temperature. This restricted dynamics directly influences the viscoelastic response, leading to increased structural rigidity upon resin addition. Furthermore, the effect of resin concentration is systematically assessed, demonstrating that, while 17 vol% resin has a negligible impact on both systems, increasing the concentration to 34 vol% in PI, results in pronounced changes in its structural and viscoelastic behaviors. Overall, this study highlights atomistic molecular dynamics simulations as powerful predictive tools for the rational design of resin–elastomer blends. Full article

The widespread use of wireless technologies raises concerns about health effects and electromagnetic interference (EMI). This study aims to investigate the EMI-shielding properties of functional textiles using modified multi-walled carbon nanotubes (MWCNT) dispersed in different polymeric matrices as coating inks. Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) combined with MWCNT showed promise. For instance, a textile coated with a PEDOT:PSS-based ink containing 5 wt.% of N-doped MWCNT with a thickness of 140 µm achieved a shielding effectiveness (SE) of 31.0 dB (221 dB µm⁻¹) in the 5.85–18 GHz range. This fabric is classified as ‘excellent’ for general use and may be suitable for EMI-protective clothing. Some tests using silicone as a polymer matrix demonstrated improved SE through resonance phenomena. Full article

Smart healthcare is rapidly emerging as a transformative paradigm, enabling simultaneous health monitoring, therapeutic intervention, and early prediction of disease onset. In this context, electrochemical monitoring systems have attracted growing interest due to their cost-effectiveness, ease of operation, miniaturization and compatibility with wearable platforms. Accordingly, conductive hydrogel-based electrochemical (bio)sensors have gained significant attention for health monitoring owing to their soft mechanical properties, high water content, excellent biocompatibility, and ability to form intimate, conformal interfaces with biological tissues. Their three-dimensional polymeric networks facilitate efficient ion transport and mechanical flexibility, making them particularly suitable for wearable and noninvasive sensing and monitoring applications. However, the intrinsically limited conductivity and catalytic activity of pristine hydrogels often constrain their electrochemical performance. To overcome these limitations, functional nanomaterials such as metal–organic frameworks (MOFs) and MXene (MX) nanosheets have been increasingly integrated into hydrogel matrices to enhance conductivity and electrochemical activity. This review provides a comprehensive and critical comparison of recent advances in MOF- and MX-integrated conductive hydrogels for electrochemical health monitoring. In addition to material design strategies and sensing performance, emerging trends in data-driven sensing aimed at improving signal interpretation and multi-analyte discrimination are systematically discussed. Key challenges related to long-term stability, biocompatibility, scalability, and intelligent system integration are critically assessed, and the future potential of these platforms within closed-loop architectures is highlighted, paving the way for next-generation conductive hydrogel-based electrochemical sensors in smart healthcare applications. Full article

Background/Objectives: The integrity of proximal contact and marginal adaptation in Class II composite restorations is essential for mechanical stability, interfacial integrity, and long-term clinical performance. These outcomes are strongly influenced by the matrix system used during restoration. This systematic review aimed to evaluate the performance of different matrix systems in restoring posterior proximal cavities, with a specific focus on their interaction with composite materials. Materials and Methods: A systematic literature search was performed in PubMed, Cochrane Library, ScienceDirect, and Scopus for studies published between 2014 and 2024. Clinical and in vitro studies comparing different matrix systems used in Class II posterior composite restorations were included. Sixteen studies met the eligibility criteria. Risk of bias was assessed using the RoB 2 tool for randomized clinical trials and the ROBINS-I tool for non-randomized studies. Results: Sectional matrix systems consistently demonstrated superior performance in achieving anatomically accurate and tight proximal contacts compared with circumferential and transparent matrix systems. Metal matrices generally showed better contact tightness and marginal adaptation than transparent matrices, likely due to their higher rigidity and improved resistance to deformation during composite placement and polymerization. The adjunctive use of separation rings and contact-forming instruments further enhanced proximal contact quality and marginal integrity. Regarding composite types, high-viscosity bulk-fill composites provided better marginal adaptation and proximal contact tightness than flowable bulk-fill and conventional composites. Conclusions: Within the limitations of the included studies, proximal contact quality and marginal adaptation in Class II composite restorations are influenced by the matrix system, composite material behavior, and clinical application protocol. Sectional metal matrix systems combined with separation rings appear to be associated with improved outcomes in the included studies, while auxiliary contact-forming instruments may further improve restorative outcomes. Full article

The selective removal of radioactive cesium-137 and strontium-90 from high-salinity radioactive wastewater remains a critical challenge, as competing ions reduce adsorption efficiency and selectivity. In this study, high-performance granulated adsorbents were developed based on alkali-activated geopolymer matrices to enhance sorption performance. The adsorbents were synthesized by inorganic polymerization, and mechanically robust granules with controlled porosity and surface chemistry were obtained. Batch sorption experiments conducted in simulated seawater demonstrated greater than 99% removal efficiencies for cesium and strontium. Isotherm modeling confirmed high maximum sorption capacities (up to 0.41 meq/g for Cs⁺ and 5.07 meq/g for Sr²⁺). Continuous fixed-bed column tests demonstrated sustained removal efficiencies for the optimized adsorbents. Structural analyses, including scanning electron microscopy, energy-dispersive X-ray spectroscopy mapping, and X-ray diffraction, confirmed uniform elemental distribution and crystalline phases consistent with selective sorption mechanisms. Assessment of mechanical strength revealed sufficient compressive strengths to ensure operational durability under hydraulic stress. These findings demonstrate that the synthesized geopolymer-based granules are a potentially effective and versatile solution for the comprehensive treatment of radioactive wastewater. Full article

The research hypothesis was that adjusting the content of the quaternary ammonium urethane dimethacrylate monomer bearing an N-dodecyl substituent (QAUDMA-12) would yield dental matrices with high antimicrobial activity, good biocompatibility, and favorable physicochemical properties. The research hypothesis was verified for six Bis-GMA, TEGDMA, and UDMA copolymers containing from 2.5 to 40 wt.% QAUDMA-12 by determining their degree of conversion, hardness, flexural properties, water behavior, antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Candida albicans, and cytotoxicity towards L929 mouse fibroblast cells. The research hypothesis was confirmed. Copolymers containing less than 30 wt.% QAUDMA-12 exhibited favorable polymerization efficiency, water sorption and solubility, and mechanical properties comparable to those of conventional Bis-GMA/TEGDMA systems. At the same time, they showed no cytotoxic effects toward mouse fibroblast cells. The results of antimicrobial tests show that the minimum QAUDMA-12 concentration providing sufficient antimicrobial activity was 20 wt.%. Therefore, it can be concluded that the 20 wt.% concentration of QAUDMA-12 makes it possible to obtain dental matrices that are non-toxic, exhibit antimicrobial activity, and possess the desired physico-mechanical performance. Full article

This study presents a novel modified polylactic acid (PLA) composite material engineered to simultaneously achieve enhanced mechanical performance, crystallinity, degradability, and antibacterial activity through the incorporation of multi-arm Zn/CFR-PLA modifiers, derived from ZnO-loaded phenolic resin microspheres. The modifiers were synthesized via ring-opening polymerization (ROP) of lactide, initiated by phenolic resin microspheres with multiple surface hydroxyl groups, where multi-arm architecture was tailored to improve compatibility and interfacial bonding with PLA matrices. Mechanical characterization revealed significant reinforcement and toughening effects: the (Zn/CFR₂-PLLA)₂/PLLA composite exhibited an elongation at break of 102.7% (≈13-fold higher than pristine PLA) and a tensile strength of 19.6 MPa, alongside markedly improved impact strength. Notably, the Zn/CFR₂-PDLA/PLLA composite, leveraging stereocomplex formation between PDLA and PLLA, achieved a higher tensile strength of 27.2 MPa with an elongation at break of 47.3%. Furthermore, the release of zinc ions from the modifiers endowed the composites with exceptional antibacterial activity, achieving more than 98% inhibition against Escherichia coli and Staphylococcus aureus. The composites also demonstrated degradability and processability, as melt-spun PLA fibers derived from them exhibited enhanced modulus (up to 4.51 GPa) and moisture-wicking capability. The composites can serve as potential candidates for biodegradable packaging films, antibacterial textiles for medical or hygienic uses, and sustainable materials for consumer products. Full article

Ion chromatography (IC) serves as a pivotal technique in trace ion analysis, and the separation performance of IC is largely determined by the properties of stationary phases. In contrast to silica-based matrices, polymer-based stationary phases have garnered significant interest owing to their outstanding pH stability and mechanical robustness. However, unmodified polymer matrices usually lack necessary ion exchange functions and selectivity; therefore, precise functional modification is the key to improving their chromatographic separation performance. This paper provides a systematic overview of recent advances in the synthesis and functional modification of polymer-based anion exchange chromatography stationary phases over the past few years. Firstly, the types and characteristics of polymer matrices commonly used for functional modification are summarized; secondly, the origin and improvement of common synthesis methods such as microporous membrane emulsification, droplet microfluidics, suspension polymerization, emulsion polymerization, soap-free emulsion polymerization, precipitation polymerization, dispersion polymerization, and seed swelling are introduced according to the molding methods of polymer matrices; furthermore, the principles, characteristics, and development status of mainstream functionalization strategies, including chemical derivatization, surface grafting, latex agglomeration, and hyperbranching, are emphasized. Finally, the existing challenges and prospective development trends in this field are discussed and outlooked, with the purpose of offering insights for the targeted design and practical application of high-performance polymer-based anion exchange chromatography stationary phases. Full article

Ciprofloxacin, being a widely used antibiotic agent, has sparked growing interest in the field of molecularly imprinted polymers (MIP) for its selective recognition and removal. This review provides a comprehensive analysis of the recent advances in the synthesis and applications of ciprofloxacin-imprinted polymers. The examination of synthesis compositions for the preparation of these polymers includes thorough discussions on functional monomers, crosslinkers, initiators, and solid supports. Various imprinting techniques, including bulk, precipitation, co-precipitation, and surface polymerization, have been assessed for the fabrication of the imprinted polymers. Furthermore, the advancing imprinting techniques, encompassing nano-scale imprinting, multi-functional monomers, multi-template imprinting, and electrochemical imprinting, are also highlighted. Additionally, an extensive exploration of the diverse applications of these polymers is also presented. These applications encompass selective separation and removal of ciprofloxacin from environmental samples, visual and electrochemical detection in complex matrices, their use as a stationary phase for HPLC, drug release, and photocatalysis. This review offers valuable insights into the current advancements and potential future directions in the development of ciprofloxacin-imprinted polymers, emphasizing their importance in diverse analytical and environmental applications. Full article

Traditional flexible polyurethane (PU) foams frequently exhibit limited mechanical support and suboptimal moisture–heat regulation, which can compromise the microenvironmental comfort required for high-quality sleep. In this study, natural luffa fibers (LF) were incorporated as a microstructural modifier to simultaneously enhance the mechanical and moisture–heat regulation performance of PU foams. PU/LF composite foams with varying LF loadings were prepared via in situ polymerization, and their foaming kinetics, cellular morphology evolution, and physicochemical characteristics were systematically investigated. The results indicate that LF functions both as a reinforcing skeleton and as a heterogeneous nucleation site, thereby promoting more uniform bubble formation and controlled open-cell development. At an optimal loading of 4 wt%, the composite foam developed a highly interconnected porous architecture, leading to a 7.9% increase in tensile strength and improvements of 19.4% and 22.6% in moisture absorption and moisture dissipation rates, respectively, effectively alleviating the heat–moisture accumulation typically observed in unmodified PU foams. Ergonomic pillow prototypes fabricated from the optimized composite further exhibited enhanced pressure-relief performance, as evidenced by reduced peak cervical pressure and improved uniformity of contact-area distribution in human–pillow pressure mapping, together with an increased SAG factor, indicating improved load-bearing adaptability under physiological sleep postures. Collectively, these findings elucidate the microstructural regulatory role of biomass-derived luffa fibers within porous polymer matrices and provide a robust material basis for developing high-performance, sustainable, and ergonomically optimized sleep products. Full article

This study presents the fabrication of composite photoelectrodes containing halogenated phthalocyanines (F₁₆CuPc and MnPcCl) embedded in polymeric matrices of PEDOT:PSS (poly(2,3-dihydrothieno-1,4-dioxin)-poly(styrenesulfonate)) and PLA (polylactic acid biopolymer). These composites were deposited on PET, palm leaf, and wheat bagasse recyclable substrates, and were morphologically characterized. The reflectance for F₁₆CuPc/PEDOT:PSS is less than 8.5%, and that for MnPcCl/PLA changes depending on the substrate, ranging between 10% and 40%. Additionally, in the case of F₁₆CuPc/PEDOT:PSS, the Kubelka–Munk band gap is 3.7 eV, and in the case of F₁₆CuPc/PEDOT:PSS, the band gap varied between 2.85 and 3.47 eV. The composites were evaluated as electrodes in bio-based sustainable devices, fabricated with commercially available paper towels used as an organic membrane separator. The palm-device showed the best performance throughout its charge and discharge cycle. The device improves its performance at high speeds and reaches its highest peak at 100 mV s⁻¹ with 3.14 × 10⁴ μA. On the other hand, the greatest thermal stability for the composites is for those deposited onto bagasse substrate, reaching up to 220 °C and 357 °C for F₁₆CuPc/PEDOT:PSS and MnPcCl/PLA, respectively. Also, these composites exhibit charge–discharge behavior when studied in bio-based sustainable devices and can be used as electrodes. Full article

Shape-stabilized phase change materials (SSPCMs) have been a promising thermal energy storage (TES) solution to combine the high energy density of solid-to-liquid (SL) PCMs and the structural stability of solid–solid PCMs. Although polymeric matrices have been used for their reduced cost and ease of processability, few have evaluated the use of crosslinked natural rubber (NR). In this study, we evaluate by differential scanning calorimetry (DSC) the preparation of room-temperature tailorable SSCPMs by the design of NR matrices with different crosslink density vulcanized by dicumyl peroxide (DCP) or sulphur, with special focus on the quantification of the content of PCM. The results indicate that the amount of PCM stable in the NR matrix is low, with PCM contents between 16 and 24% and enthalpies between 16 and 20 J·g⁻¹. Likewise, it is well-known that thermophysical properties of the PCMs vary upon confinement in a small-scale porous matrix. The confinement of the PCM in the rubber network results in a measured enthalpy below the expected value, and a melting point depression of up to 23.6 °C, dependent on crosslink density. These results highlight the structural complexity of NR-PCM composites and the need for further investigation. Full article