Polymers最新文献

The development of smart coatings with active protection is a promising approach to prolonging the service life in extreme environments. Herein, the corrosion inhibitors 2-mercaptobenzimidazole (MBI) and CeO₂ were in situ loaded onto the surface of graphene oxide (GO) by dopamine (DA) polymerization, and we ultimately obtained the multifunctional composite MBI@CeO₂@PDA@GO (MCPG). The electrochemical impedance spectroscopy (EIS) results revealed that after 30 days of immersion in the corrosive media, the |Z|_0.01 Hz value of MCPG/WEP coating remained at 3.7 × 10⁹ Ω/cm², which displayed four orders of magnitude higher than that of pure WEP coating (1.4 × 10⁵ Ω/cm²). In a 200 h salt spray test, the MCPG/WEP coating also demonstrated minimal corrosion products and bubbles, affirming the exceptional corrosion-inhibiting effect and excellent self-healing performance. Consequently, the synergistic combination of pH-sensitive properties and outstanding barrier effect imparted dual active/passive anti-corrosion capabilities to the coating, resulting in long-lasting metal protection.

Optimizing the mechanical response of structures with triple periodic minimal surfaces (TPMS) is key to their use in lightweight applications focused on energy absorption. This study evaluated the influence of cell geometry and uneven material distribution on the bending behavior of Primitive, Gyroid, and Diamond structures. Nylon 12 CF samples were produced using an additive method (FDM) with volume fractions of 35%, 40%, 45%, and 55%. The mechanical response was quantified using a three-point bending test according to ISO 178, from which the maximum force (F_max), flexural strength (σ_f), absorbed energy (E_abs), and ductility index (µ_d) were determined. The Primitive structure achieved the highest strength at a volume fraction of 45% (σ_f = 28.35 MPa; F_max = 756 N). The Primitive structure also demonstrated the highest toughness with a ductility index of up to µ_d = 8.62 at 55%. The study identified a significant deformation phenomenon in the Gyroid structure, where the sample with a volume fraction of 45% showed higher absorbed energy (34.58 J) than the sample with a higher fraction of 55% (26.81 J). This finding suggests that targeted material inhomogeneity (gradient) can, under specific conditions, lead to stabilization of the deformation mechanism through progressive collapse, thereby increasing energy efficiency. The Primitive structure proved to be the most resistant to uneven material distribution and, with a volume fraction of 45-55%, offers an optimal compromise between high strength and toughness, making it most suitable for the design of gradient structures subjected to bending loads.

Polymer composites and nanocomposites have become indispensable in aerospace, automotive, energy, electronics, soft robotics, and biomedical applications due to their high specific stiffness, strength, and manufacturability with highly tailorable multifunctional performance. Their rational design is complicated by strong, multiscale couplings among microstructural heterogeneity, interfacial physics, anisotropic response, and time- and temperature-dependent behavior, spanning molecular to structural length scales. This review provides a comprehensive survey of the principal computational methodologies used to predict and interpret the mechanical behavior of polymer composites and nanocomposites, highlighting the capabilities, specialties, and complementary roles of different modeling tools. This review first summarizes the essential physical characteristics governing polymer composites and nanocomposites. We then examine computational modeling approaches for polymer composites across four length scales: the constituent scale, microscale, mesoscale, and macroscale. For each scale, the primary modeling objectives, characteristic capabilities, and domains of applicability are discussed in the context of the existing literature. Cross-scale relationships and bridging strategies among these scales are also discussed, emphasizing how lower-scale simulations inform higher-scale models. The review then focuses on computational modeling of polymer nanocomposites, with particular attention to atomistic and coarse-grained molecular dynamics methods. Representative atomistic simulations, which capture interfacial structure, reinforcement-matrix interactions, and nanoscale mechanisms, are discussed. This is followed by discussions on coarse-grained approaches that extend the accessible length and time scales. Finally, we discuss how atomistic and coarse-grained models complement each other within integrated multiscale frameworks, enabling predictive links between nanoscale physics and macroscopic mechanical behaviors.

In this work, bimetallic TiO₂-ZnO nanoparticles were phytosynthesized in molar ratios of 1Ti:1Zn, 2Ti:1Zn, and 1Ti:2Zn, using plant extract of Ruta graveolens leaves as reductant agent. The TiO₂-ZnO nanoparticles were supported on chitosan films at concentrations of 0.1 and 0.2% (w/v). The resulting films were characterized by FTIR, TGA-DT and DSC analysis, confirming an adequate impregnation of the nanoparticles in the polymeric matrix and stability against temperature variations, while swelling tests revealed good structural strength without appreciable deformation. The antimicrobial activity of the membranes was evaluated by the disk diffusion method (Kirby-Bauer) against Escherichia coli, Staphylococcus aureus and Candida albicans. It was observed that the membranes having nanoparticles of stoichiometric ratios 1Ti:1Zn and 2Ti:1Zn presented higher microbicidal activity, especially against Gram-positive bacteria and yeast. The microbicidal effect of TiO₂-ZnO nanoparticles varies with each strain. The inhibition halo of the 2Ti:1Zn sample grow up to 14% in most tests, while the 1Ti:2Zn sample produces the smallest halo for E. coli and C. albicans; however, for S. aureus, the halo improves by up to 33%. This phenomenon is attributed to the stoichiometric arrangement capable of inducing oxidative stress. The results show the potential of chitosan films impregnated with TiO₂-ZnO NPs as functional materials for biomedical applications, especially in the development of dressings with enhanced antimicrobial properties.

This study aimed to evaluate the effect of preheating on the push-out bond strength (PBS) and microhardness (HV) of fiber-reinforced flowable and injectable composites and to compare them with dual-cure resin-cement for post cementation. Fifty premolars were endodontically treated, and post spaces were prepared. Specimens were divided into five groups (n = 10) based on the resin luting material. After adhesive application, fiber posts were luted with dual-cure resin-cement (LinkForce), fiber-reinforced flowable composites (EverX Flow; non-heated/preheated), and injectable composites (G-aenial Universal Injectable; non-heated/preheated). After 24 h, roots were sectioned (coronal, middle, apical) for PBS testing (Instron). For HV, 10 specimens per resin luting material were prepared, and top/bottom microhardness was measured to assess the depth of cure. Data were analyzed with two-way ANOVA and post hoc Tukey tests (p < 0.05). Both types of resin luting material and preheating significantly affected PBS and HV (p = 0.0001). Preheated EverX Flow showed significantly higher PBS and HV than LinkForce, while G-aenial Injectable exhibited the lowest values (p < 0.05). Within each resin luting material, PBS significantly decreased from the coronal to the apical region (p = 0.0001). Preheated fiber-reinforced flowable composites demonstrate improved microhardness and adhesion, offering a reliable alternative to the dual-cure resin-cements for fiber post cementation.

Residual stresses are a persistent challenge in the additive manufacturing of composite parts by FFF (Fused Filament Fabrication) and can impair dimensional accuracy and mechanical performance. This article evaluates reflection photoelasticity (PhotoStress) as a full-field optical technique to visualize and compare residual-stress relaxation in ASA (Acrylonitrile Styrene Acrylate) reinforced with aramid fibers. The approach combines a controlled AWJ (Abrasive Water Jet) relief cut to induce local stress release with subsequent optical recording of isochromatic fringe fields using a reflection polariscope. Samples with thicknesses of 2-10 mm were manufactured and evaluated in two conditions: non-annealed and after annealing (80 °C/5 h). Under identical optical settings, no discernible isochromatic fringes were detected for 2-6 mm (Nmaxlobal < 0.60 in both conditions), whereas resolvable fringe patterns were observed for 8-10 mm. For 8 mm, the response was localized near the relief cut, with Nmax,global = 1.0 in the non-annealed condition and Nmax,global < 0.60 after annealing. For 10 mm, the response was more spatially extensive, and annealing reduced the global maximum from Nmax,global = 1.2 to 0.9. Taken together, these results demonstrate that reflection photoelasticity supports comparative full-field visualization of residual-stress relaxation in FFF composite specimens under fixed measurement conditions. In addition, an AWJ relief cut constitutes a practical and repeatable stress-release feature with limited additional thermal influence in the present configuration.

Three-dimensional bioprinting revolutionized tissue and organ replacement by enabling the precise deposition of living cells and biomaterials, making it ideal for biomedical applications. Natural polymers are commonly used as bioink for their biocompatibility and bioactivity. Among them, type I collagen, the most abundant protein of extracellular matrix, is commonly used as bioink. However, mammalian-derived collagens raise concerns related to zoonotic disease transmission, religious restrictions, and immunogenicity. Fish-derived collagen represents a safer and more sustainable alternative, although its rapid degradation and limited mechanical properties remain significant challenges. In this study, the printability of a novel fish collagen ink was assessed for micropatterned scaffolding by extrusion. In order to overcome material-related challenges, the effect of UV-induced crosslinking was investigated. Morphological, rheological, and physicochemical characterizations-including thermal behavior, degradation resistance, exposed chemical groups, and roughness-were performed before and after UV treatment. Results demonstrated that UV crosslinking significantly improved the structural integrity and stability of the printed scaffolds. These findings support the potential of UV-crosslinked fish collagen as biomaterial ink for regenerative medicine and tissue engineering applications.

A systematic evaluation of meta-substitution and backbone molecular weight in diamine-based benzoxazines was conducted to investigate the impact on melt processability, network development, and the structure-property relationships in polybenzoxazines. Six benzoxazine monomers derived from aryl ether diamines were synthesized, with controlled levels of meta-substitution and varying numbers of ether-bridged phenyl rings in the monomer backbone. Meta-substitution was found to suppress crystallinity in high-purity benzoxazine monomers and lower onsets of polymerization were observed due to meta-positioning of the terminal diamine rings. Terminal diamine meta-substitution also led to higher polymerization enthalpies, attributed to the emergence of an additional polymerization mechanism that increased the glass transition temperature up to 60 °C and delayed the onset of mass loss degradation. Benzoxazines with glass transition temperatures approaching 200 °C are susceptible to Mannich bridge degradation during polymerization, and this additional polymerization pathway both illustrates the nuanced complexities of benzoxazine structure-property relationships as well as provides a potential design strategy for benzoxazines with high glass transition temperatures approaching 250 °C.

Phase change materials (PCMs) have attracted significant attention for their capacity to store and release large amounts of latent heat in response to ambient temperature variations, offering an effective strategy for thermal regulation in buildings. Meanwhile, recent research is focused on microencapsulated phase change materials (MPCMs), which provide enhanced thermal efficiency, improved stability, and easier integration into construction materials. This study stands apart from offering a structured comparative analysis of PCM and MPCM systems. Using detailed synthesis tables, the review systematically evaluates materials, encapsulation approaches, and performance indicators. The review presents an integrative framework that correlates materials' thermophysical properties with specialized simulation software and region-specific climatic conditions. MPCMs are assessed in terms of composition, phase change characteristics, and encapsulation techniques, with complex information condensed into practical selection criteria. Furthermore, MPCM products covering phase change temperature ranges from 18 °C to 32 °C are systematically aligned with specific climate zones and life cycle assessment outcomes, offering a clear framework for optimization. The polymers play a vital role in MPCM technology, and their applications for buildings have been studied thoroughly. This work also aims to guide research and development toward scalable, energy-efficient, and sustainable building technologies for both academic and industrial stakeholders.

Recent advances in polymeric composites emphasize the incorporation of natural and mineral fillers to enhance sustainability while maintaining mechanical performance. Studies have shown that lignocellulosic residues and nanostructured clays can improve stiffness and thermal stability, although interfacial compatibility remains a key challenge. This study investigates the mechanical behavior of epoxy composites reinforced with eucalyptus powder and montmorillonite clay, aiming to develop sustainable materials with reduced environmental impact. Formulations containing 5%, 10%, and 20% by volume of each particulate, as well as hybrid combinations, were produced and tested for impact, flexural, and compressive strength. Higher particulate contents were not explored, as fractions above 20% considerably increased viscosity, hindering proper mixing and specimen fabrication. Scanning electron microscopy (SEM) revealed irregular morphologies and heterogeneous dispersion of both fillers. The reduction in impact strength observed across all formulations was mainly attributed to poor interfacial adhesion and void formation, as no chemical or surface treatments were applied to enhance compatibility between the particulates and the epoxy matrix. Conversely, compressive strength improved at low filler contents (5-10%), suggesting a more efficient load transfer under compressive stress. Composites with up to 10% particulate presented a viable balance between mechanical performance and sustainability, showing potential for non-structural applications such as panels, coatings, and eco-friendly construction components. Overall, the results highlight the feasibility of using natural and mineral particulates as sustainable reinforcements, albeit with performance constraints at higher loadings.