Search Results (819)

UV-C radiation has emerged as a germicidal agent against pathogens, particularly following the COVID-19 pandemic. While UV-C effectively reduces cross-contamination in hospitals, it induces photodegradation in polymer devices, potentially damaging and posing risks to patient safety. Therefore, it is crucial to detect the effects of UV-C photodegradation on early stages, as well as the effects of prolonged UV-C exposure. In this study, we investigated the UV-C photodegradation (254 nm, 471 kJ/mol) of isotactic polypropylene homopolymer (PP), commonly used in medication packaging. The impact of UV-C on PP was evaluated through rheology and infrared spectroscopy. Surface energy was measured by the contact angles formed by drops of water and diiodomethane. The effects of photodegradation on the polymer’s morphology were examined using scanning electron microscopy, and the melting temperature and crystallinity by differential scanning calorimetry. Lastly, the effect of UV-C on molecular mobility was studied using ¹H Time Domain Nuclear Magnetic Resonance (¹H TD-NMR). These techniques proved to be valuable tools for identifying the early stages of UV-C photodegradation, and ¹H TD-NMR was a sensitive method to identify the chain branching as a photodegradation product. This study highlights the impact of UV-C on PP photodegradation and hence the importance of understanding UV-C-induced degradation. Full article

Nanoparticle superlattices—periodic assemblies of uniformly spaced nanocrystals—bridge the nanoscale precision of individual particles with emergent collective properties akin to those of bulk materials. Recent advances demonstrate that multivalent ions and charged polymers can guide the co-assembly of nanoparticles, imparting electrostatic gating and enabling semiconductor-like behavior. However, the specific roles of anion geometry, valency, and charge density in mediating ion transport remain unclear. Here, we employ coarse-grained molecular dynamics simulations to investigate how applied electric fields (0–0.40 V/nm) modulate ionic conductivity and spatial distribution in trimethylammonium-functionalized gold nanoparticle superlattices assembled with four phosphate anions of distinct geometries and charges. Our results reveal that linear anions outperform ring-shaped analogues in conductivity due to higher charge densities and weaker interfacial binding. Notably, charge density exerts a greater influence on ion mobility than size alone. Under strong fields, anions accumulate at nanoparticle interfaces, where interfacial adsorption and steric constraints suppress transport. In contrast, local migration is governed by geometrical confinement and field strength. Analyses of transition probability and residence time further indicate that the rigidity and delocalized charge of cyclic anions act as mobility barriers. These findings provide mechanistic insights into the structure–function relationship governing ion transport in superlattices, offering guidance for designing next-generation ion conductors, electrochemical sensors, and energy storage materials through anion engineering. Full article

Rejuvenating aged asphalt is critical for sustainable road construction and resource utilization. This paper systematically reviews the current research on rejuvenators, focusing on their classification and the micro-, and macro-properties of rejuvenated asphalt. Rejuvenators are categorized into mineral oil-based, bio-based, and compound types. Each type offers distinct advantages in recovering the performance of aged asphalt. Mineral oil-based rejuvenators primarily enhance low-temperature cracking resistance through physical dilution, while bio-based rejuvenators demonstrate superior environmental sustainability and stability. Compound rejuvenators, particularly those incorporating reactive compounds, show the best results in repairing degraded polymer modifiers and improving both low- and high-temperature properties of aged, modified asphalt. Atomic Force Microscopy (AFM), Fluorescence Microscopy (FM), and Scanning Electron Microscopy (SEM) have been applied to analyze the micro-properties of rejuvenated asphalt. These techniques have revealed that rejuvenators can restore the microstructure of aged asphalt by dispersing agglomerated asphaltenes and promoting molecular mobility. Functional groups and molecular weight changes, characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Gel Permeation Chromatography (GPC), indicate that rejuvenators effectively reduce oxidation products and molecular weight of aged asphalt, restoring its physicochemical properties. Macro-property evaluations show that rejuvenators significantly improve penetration, ductility, and fatigue resistance. Finally, this review identifies the key characteristics and challenges associated with rejuvenator applications and provides an outlook on future research directions. Full article

Eight different types of tea bags were investigated in this work using dynamic light scattering, electrophoretic mobility and nanoparticle tracking analysis methods to determine the concentration and size of released particles from the bag materials at different temperatures and times. Infrared spectroscopy and calorimetric methods confirmed that the bag material consisted of synthetic (nylon or polypropylene) or natural polymers (cellulose). The size of the released particles lies in the range of 200 nm^–1 µm with an initial bimodal distribution and with an average diameter of about 600 nm. The concentration of released particles increases with increasing temperature and brewing time. The released particles of synthetic polymers remain quite stable and are not affected by natural enzymes, while cellulose particles are easily degraded by the proteolytic complex Morikrase. When analyzing the electrophoretic mobility, it was found that the released particles have a negative surface charge, which probably determines the absence of cytotoxicity established on the epithelial cell line Caco-2 even at the maximum values of the observed particle concentrations (14 × 10⁹ particle/L for synthetic polymers and 170 × 10⁹ particle/L for cellulose). Full article

Owing to multiple non-covalent interactions, ionic groups impart unique chemical and physical properties into polymers including ion conductivity/mobility, permeation, and intrinsic healability. Ionenes contain ionic groups in their polymer backbone, which offer great versatility in polymer design. Herein, selected aliphatic and aromatic imidazoles were synthesized, which were used as monomeric building blocks for the preparation of thermoplastic ionenes by following a Sn2 step growth reaction across organic halides. The structure and molecular weight of the polymers was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) techniques. Once polymerized, anion-exchange reactions were carried out to replace the halides with four other counter-anions. Subsequently, the effect of the nature of the anion and the cation on the polymers’ thermal and hygroscopic properties was studied in detail by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and FTIR spectroscopy. Depending on the chemical structures of the polymeric cations and the related anions, tailored polymers with a glass transition temperature (T_g) in the range of 30 °C to 131 °C and a thermal stability varying between 170 °C and 385 °C were obtained. Full article

Nanostructures composed of semiconducting polymers that adopt highly ordered molecular arrangements at the nano- and microscale typically exhibit enhanced optoelectronic properties. In this study, we aim to establish a comprehensive correlation between nanostructures with varying degrees of molecular order—fabricated using diverse processing methods—and their tailored optoelectronic properties, as demonstrated by various energy devices. These properties include carrier mobility, electrical conductivity, and photovoltaic capabilities measured predominantly in films tens to hundreds of nanometers thick based on semiconducting polymers. Full article

Gelatin is a collagen-derived biopolymer widely used in food, pharmaceutical and biomedical applications due to its biocompatibility and gelling ability. However, gelatin hydrogels suffer from unstable mechanical strength, limited thermal resistance and susceptibility to microbial contamination. The main aim of the present study is to investigate the influence of gelatin cryostructuring followed by photo-induced menadione sodium bisulfite (MSB) chemical crosslinking on the structural and functional characteristics of mammalian and fish gelatin hydrogels. The integration of scanning electron microscopy, dielectric spectroscopy and rheological experiments provides a comprehensive view of the of molecular, morphological and mechanical properties of gelatin hydrogels under photo-induced chemical crosslinking. The SEM results revealed that crosslinked hydrogels are characterized by enlarged pores compared to non-crosslinked systems. For mammalian gelatin, multiple pores with thin partitions are formed, giving a dense and stable polymer network. For fish gelatin, large oval pores with thickened partitions are formed, preserving a less stable ordered architecture. Rheological data show strong reinforcement of the elastic and thermal stability of mammalian gelatin. The crosslinked mammalian system maintains the gel state at higher temperatures. Fish gelatin exhibits reduced elasticity retention even after crosslinking because of a different amino acid composition. Dielectric results show that crosslinking increases the portion of bound water in hydrogels considerably, but for fish gelatin, bound water is more mobile, which may explain weaker mechanical properties. Full article

Hydrogels comprise three-dimensional networks of hydrophilic polymers and have attracted considerable interest in various sectors, including the biomedical, pharmaceutical, agricultural, and food industries. These materials offer significant benefits for food packaging applications, such as high mechanical strength and excellent water absorption capacity, thereby contributing to the extension of product shelf life. Therefore, the aim of this study is to compare the performance of citric acid and glutaraldehyde as crosslinking agents in gelatine-based hydrogels reinforced with cellulose nanocrystals (CNC), contributing to the development of safe and environmentally responsible materials. The hydrogels were prepared using the casting method and characterised in terms of their physical, mechanical, and structural properties. The results indicated that hydrogels crosslinked with glutaraldehyde exhibited higher opacity, lower transparency, and greater mechanical strength, whereas those crosslinked with citric acid demonstrated improved clarity, reduced water permeability, and enhanced swelling capacity. The incorporation of CNC further improved mechanical strength, reduced weight loss, and altered both surface homogeneity and optical properties. Microstructural results obtained by SEM were consistent with the mechanical properties evaluated (TS, %E, and EM). The Gel-ca hydrogel displayed the highest elongation value (98%), reflecting better cohesion within the polymeric matrix. In contrast, films incorporating CNC exhibited greater roughness and cracking, which correlated with increased rigidity and mechanical strength, as evidenced by the high Young’s modulus (420 MPa in Gel-ga-CNC2). These findings suggest that the heterogeneity and porosity induced by CNC limit the mobility of polymer chains, resulting in less flexible and more rigid structures. Additionally, the DSC analysis revealed that gelatine hydrogels did not exhibit a well-defined Tg, due to the predominance of crystalline domains. Systems crosslinked with citric acid showed greater thermal stability (higher Tm and ΔH_m values), while those crosslinked with glutaraldehyde, although mechanically stronger, exhibited lower thermal stability. These results confirm the decisive effect of the crosslinking agent and CNC incorporation on the structural and thermal behaviour of hydrogels. In this context, the application of hydrogels in packaged products represents an eco-friendly alternative that enhances product presentation. This research supports the reduction in plastic consumption whilst promoting the principles of a circular economy and facilitating the development of materials with lower environmental impact. Full article

Thick active layers are crucial for scalable production of organic photodetectors (OPDs). However, most OPDs with active layers thicker than 200 nm typically exhibit decreased photocurrents and responsivities due to exciton diffusion and prolonged charge transport pathways. To address these limitations, we designed and synthesized PFBDT-8ttTPD, a fluorinated polymer donor. The strategic incorporation of fluorine effectively enhanced the charge carrier mobility, enabling more efficient charge transport, even in thicker films. OPDs combining PFBDT−8ttTPD with IT−4F or Y6 non-fullerene acceptors showed a substantially lower dark current density (J_d) for active layer thicknesses of 250−450 nm. Notably, J_d in the IT-4F-based devices declined from 8.74 × 10⁻⁹ to 4.08 × 10⁻¹⁰ A cm⁻² under a reverse bias of −2 V, resulting in a maximum specific detectivity of 3.78 × 10¹³ Jones. Meanwhile, Y6 integration provided near-infrared sensitivity, with the devices achieving responsivity above 0.48 A W⁻¹ at 850 nm and detectivity over 10¹³ Jones up to 900 nm, supporting broadband imaging. Importantly, high-quality thick films (≥400 nm) free of pinholes or defects were fabricated, enabling scalable production without performance loss. This advancement ensures robust photodetection in thick uniform layers and marks a significant step toward the development of industrially viable OPDs. Full article

Spent coffee grounds represent an abundant waste resource with potential for sustainable material applications. This study investigates the use of carbonized spent coffee grounds (CSCG) as fillers in polyurethane (PU) coatings for carbon fiber-reinforced polymer (CFRP) substrates to enhance mechanical durability and anti-icing performance. SCGs were dried, sieved (<100 µm), and oxidatively carbonized in air at 100–300 °C for 60–120 min, then incorporated into PU at 1 or 5 wt.% and applied by spray-coating. A full-factorial design was employed to evaluate the effects of carbonization temperature, particle size, and filler loading. The optimized formulation (300 °C, 100 µm, 5 wt.%) showed the highest water contact angle (103.5°), lowest work of adhesion (55.8 mJ/m²), and improved thermal stability with 60% char yield. Mechanical testing revealed increased tensile modulus with reduced strain, and differential scanning calorimetry indicated an upward shift in glass-transition temperature, suggesting restricted chain mobility. Ice formation at 0 °C was sparse and discontinuous, attributed to lowered polar surface energy, rough surface texture, and porous carbon morphology. These results demonstrate that CSCGs are effective sustainable fillers for PU coatings, offering combined improvements in mechanical, thermal, and anti-icing properties suitable for aerospace, wind power, and other icing-prone applications. Full article

The synthesis of two series of poly(lactic acid) (PLA)-based polymer nanocomposites (PNCs) filled with small amounts (0.5 and 1%) of Ag and Cu nanoparticles (NPs) was performed. Moreover, two methods for the PNC synthesis were performed, namely, ‘conventional mixing techniques’ and ‘in situ ring opening polymerization (ROP)’. The latter method was employed for the first time; moreover, it was found to be more effective in achieving very good NP dispersion in the polymer matrix as well as the formation of interfacial polymer–NP interactions. The in situ ROP for PLA/Cu was not productive due to the oxidation of Cu NPs being faster than the initiation of ROP. The presence of NPs resulted in suppression of the glass transition temperature, T_g (23–60 °C), with the effects being by far stronger in the case of ROP-based PNCs, e.g., exhibiting T_g decrease by tens of K. Due to that surprising result, the ROP-based PLA/Ag PNCs exhibited elevated ionic conductivity phenomena (at room temperature). This can be exploited in specific applications, e.g., mimicking the facilitated small molecules permeation. The effects of NPs on crystallinity (2–39%) were found opposite between the two series. Crystallinity was facilitated/suppressed in the mixing/ROP -based PNCs, respectively. The local and segmental molecular mobility map was constructed for these systems for the first time. Combining the overall data, a concluding scenario was employed, that involved the densification of the polymer close to the NPs’ surface and the free volume increase away from them. Finally, an exceptional effect was observed in PLA + 0.5% Ag (ROP). The crystallization involvement resulted in a severe suppression of T_g (−25 °C). Full article

The retrogradation of starch strongly influences the texture and stability of starchy foods. This study applied low-field nuclear magnetic resonance (LF NMR) to examine the effect of buckwheat hull (BH) fiber and green barley (GB) on water dynamics in normal (NPS) and waxy (WPS) potato starch gels. Relaxation times (T₁, T₂) and mean correlation times (τ_c) were monitored during 15 days of storage to evaluate changes in water mobility and starch–polymer interactions. Results showed that WPS, with its high amylopectin content, retrograded earlier than NPS. The addition of BH inhibited conformational changes associated with water binding in WPS gels, indicating that insoluble fiber entrapped water within the amylopectin network. Conversely, GB promoted higher τ_c values in WPS, reflecting enhanced ordering and reduced water mobility, while its impact on NPS was minor. In NPS systems, BH decreased τ_c, suggesting disruption of amylose-driven structural reorganization. These findings demonstrate that BH and GB exert opposite effects on starch retrogradation and highlight their potential as functional additives for tailoring texture and stability in starch-based food systems. Full article

Amorphous solid dispersions (ASDs) represent a promising formulation strategy for improving the solubility and bioavailability of poorly water-soluble drugs, a major challenge in pharmaceutical development. This review provides a comprehensive analysis of the physicochemical principles underlying ASD stability, with a focus on drug–polymer miscibility, molecular mobility, and thermodynamic properties. The main manufacturing techniques including hot-melt extrusion, spray drying, and KinetiSol^® dispersing are discussed for their impact on formulation homogeneity and scalability. Recent advances in excipient selection, molecular modeling, and in silico predictive approaches have transformed ASD design, reducing dependence on traditional trial-and-error methods. Furthermore, machine learning and artificial intelligence (AI)-based computational platforms are reshaping formulation strategies by enabling accurate predictions of drug–polymer interactions and physical stability. Advanced characterization methods such as solid-state NMR, IR, and dielectric spectroscopy provide valuable insights into phase separation and recrystallization. Despite these technological innovations, ensuring long-term stability and maintaining supersaturation remain significant challenges for ASDs. Integrated formulation design frameworks, including PBPK modeling and accelerated stability testing, offer potential solutions to address these issues. Future research should emphasize interdisciplinary collaboration, leveraging computational advancements together with experimental validation to refine formulation strategies and accelerate clinical translation. The scientists can unlock the full therapeutic potential with emerging technologies and a data-driven approach. Full article

A ceramic-based wideband capacitive-fed patch-loaded multi-layered rectangular dielectric resonator antenna (CFPL-ML-RDRA) with a compact form factor is proposed in this paper. The proposed antenna is composed of two ceramic substrates and a polymer as an adhesive. A capacitive-fed metallic patch structure is located on the top side of the bottom ceramic substrate. This novel structure generates two distinct resonant modes: the fundamental resonant mode of the RDRA and a hybrid resonant mode, which was confirmed through electric field (E-field) analysis and parametric studies. By merging these two resonant modes, the proposed antenna achieves a wide impedance bandwidth of 5.5 GHz, sufficient to cover the fifth-generation (5G) millimeter-wave (mmWave) frequency bands n257, n258, and n261 (5.25 GHz), while reducing the height of the DRA by 38.5% compared to the conventional probe-fed RDRA (PF-RDRA). Additionally, the 4 dBi realized gain bandwidth of the proposed CFPL-ML-RDRA is 5.4 GHz, which is 28.6% broader than that of the conventional PF-RDRA. To experimentally verify the antenna’s performance, the CFPL-ML-RDRA mounted on a test printed circuit board with a small ground size of 3.2 × 3.2 mm² was fabricated and characterized. The measured data align well with the simulated data. Furthermore, excellent antenna array performance was achieved based on array simulations. Therefore, the proposed antenna structure is well-suited for 5G mmWave mobile applications. Full article

Melt-spun PA6/TiO₂ fibers with TiO₂ modified by silane coupling agents KH550 and KH570 at 0, 1.6, and 4 wt% provide a practical testbed to address three fiber-centric gaps: transferable interphase quantification, interphase-resolved indications of compatibility, and a reproducible kinetics–structure–property link. This work proposes, for the first time at fiber scale, a four-phase partition into crystal (c), crystal-adjacent rigid amorphous fraction (RAF-c), interfacial rigid amorphous fraction (RAF-i), and mobile amorphous fraction (MAF), and extracts an interfacial triad consisting of the specific interfacial area (S_v), polymer-only RAF-i fraction expressed per composite volume (Γ_i), and interphase thickness (t_i) from SAXS invariants to establish a quantitative interphase-structure–property framework. A documented SAXS/DSC/WAXS workflow partitions the polymer into the above four components on a polymer-only basis. Upon filling, Γ_i increases while RAF-c decreases, leaving the total RAF approximately conserved. Under identical cooling, DSC shows the crystallization peak temperature is higher by 1.6–4.3 °C and has longer half-times, indicating enhanced heterogeneous nucleation together with growth are increasingly limited by interphase confinement. At 4 wt% loading, KH570-modified fibers versus KH550-modified fibers exhibit higher α-phase orientation (Hermans factor f(α): 0.697 vs. 0.414) but an ~89.4% lower α/γ ratio. At the macroscale, compared to pure (neat) PA6, 4 wt% KH550- and KH570-modified fibers show tenacity enhancements of ~9.5% and ~33.3%, with elongation decreased by ~31–68%. These trends reflect orientation-driven stiffening accompanied by a reduction in the mobile amorphous fraction and stronger interphase constraints on chain mobility. Knitted fabrics achieve a UV protection factor (UPF) of at least 50, whereas pure PA6 fabrics show only ~5.0, corresponding to ≥16-fold improvement. Taken together, the SAXS-derived descriptors (S_v, Γ_i, t_i) provide transferable interphase quantification and, together with WAXS and DSC, yield a reproducible link from interfacial geometry to kinetics, structure, and properties, revealing two limiting regimes—orientation-dominated and phase-fraction-dominated. Full article