Polymers最新文献

Polylactic acid (PLA) is one of the most widely used materials for fused filament fabrication (FFF) or fused deposition modeling (FDM), being recognized for its low carbon footprint, relatively low costs and good mechanical properties. Improving the mechanical and technological properties of PLA with various additives has led to the production of different types of PLA-based filaments, such as hyper PLA (HPLA), PLA, PLA+ and PLA Lite. Studies on the mechanical properties of HPLA are scarce; therefore, the objective of this paper was to determine the mechanical properties of 3D-printed HPLA under tensile and bending stress conditions and to obtain numerical models that depend on the raster pattern orientation. The principal component analysis (PCA) reveals very different results for bending compared with tension, with outcomes varying significantly depending on the orientation of the raster angle.

Peripheral nerve adhesion after surgical injury severely hinders functional nerve regeneration, leading to pain and neurological dysfunction. In this study, we developed a photocrosslinkable methacrylated gelatin (GelMA)-based hydrogel membrane that locally releases dexamethasone to simultaneously prevent adhesion and suppress inflammation. GelMA, synthesized by reacting gelatin with methacrylic anhydride, formed a stable crosslinked network, as confirmed by FT-IR spectroscopy and rheological analysis. Cytocompatibility assays showed that both GelMA and Dexa-GelMA hydrogels were non-cytotoxic to neuronal and fibroblast cell lines. In a Sprague-Dawley (SD) rat sciatic nerve injury model, implantation of the Dexa-GelMA hydrogel significantly reduced perineural adhesion and inflammation compared with the untreated control. Western blot analysis showed an approximately 80% reduction in ED-1 expression, indicating suppression of macrophage activation. Overall, the Dexa-GelMA hydrogel provides a biocompatible, multifunctional platform that integrates physical barrier function with anti-inflammatory drug delivery, showing strong potential for preventing postoperative nerve adhesion and modulating early inflammatory responses in a peripheral nerve injury model.

Elastomer-based nanocomposites combining polymer flexibility with conductive nanofillers provide lightweight, stretchable systems with tunable electromechanical properties for wearable electronics, soft robotics, and self-powered sensors. However, predicting their nonlinear response remains challenging because the observed piezoelectric-like response arises from strain-dependent interfacial polarization and evolving piezoresistive conduction pathways within heterogeneous microstructures. We introduce a continuum electro-hyperelastic framework combining the Mooney-Rivlin model for large-strain elasticity with a Helmholtz free-energy approach for electrostatic coupling. Analytical expressions for stress, electric displacement, and apparent piezoelectric coefficients are derived and implemented in finite element simulations. The model accurately reproduces the experimental mechanical, dielectric, and electromechanical behaviour of polydimethylsiloxane (PDMS) nanocomposites with 0.1-1 wt% graphene. These show increased stiffness, relative permittivity (from 3.4 to 4.0, ≈18%), and quasi-static d₃₃ coefficients (from -5.6 to -10.0 pC N^-1, ≈80% enhancement). Analytical and finite element method (FEM) results show consistent trends across the full deformation range, with Maxwell stress agreement within 10% at lower deformation levels, while deviations of 33-40% for coupled electromechanical quantities at an axial displacement u_z = ~-1 mm (~16.7% compressive strain) are attributable to three-dimensional shear effects absent from the uniaxial analytical assumption. Simulations reveal that graphene boosts Maxwell stress, yielding a four-fold increase at lower stretch ratios. This reframes PDMS-graphene composites as electro-hyperelastic materials, offering a predictive, extensible framework. It highlights apparent piezoelectricity as an emergent, tunable effect from charge redistribution in a compliant hyperelastic matrix-guiding the design of next-generation flexible devices leveraging field-induced coupling over intrinsic polarization.

Polymer powder bed fusion (PBF) is strongly influenced by powder chemistry and powder state, yet many studies discuss the materials and processing conditions in isolation. This review synthesises the literature using a powder-centred framework that connects polymer chemistry and powder production history to measurable powder descriptors, and then links these descriptors to processing windows, defect mechanisms, and application outcomes. Key descriptors include crystallinity and thermal transitions, additive packages, particle size distribution, morphology, and surface texture. Environmental sensitivities are also considered, including moisture uptake, temperature effects, and optical response. These factors are related to powder spreading, energy absorption, and melt solidification or sintering to explain how flowability, packing density, and melt dynamics govern porosity, lack of fusion, distortion, and degradation. Powder qualification is discussed together with lot-to-lot variability and lifecycle effects, including ageing, reuse, and refresh, using the indicators commonly reported in laboratory and production settings and supported by emerging in situ monitoring. Application case studies are consolidated to illustrate how powder state and process control translate into repeatable qualification targets as polymer PBF moves toward a predictable and transferable manufacturing practice.

This review examines biodegradable polymer-based core-shell nanoformulations encapsulating essential oils for acne treatment through the lens of physicochemical design and controlled delivery mechanisms. Acne is a common inflammatory skin disorder closely associated with sebum overproduction and microbial imbalance, while conventional therapies, although effective, may present long-term side effects. Increasing attention has therefore turned to sustainable dermatological materials derived from eco-friendly polymers combined with naturally active compounds. Recent advances show that core-shell nanostructures fabricated from biodegradable polymers function as physicochemically engineered carriers for volatile essential oils. They enhance their stability and protect them from premature degradation. They also enable controlled release governed by diffusion, polymer relaxation, interfacial interactions, and degradation kinetics. This review highlights how polymer chemistry, interfacial properties, particle morphology, and processing routes determine encapsulation efficiency, release profiles, and skin permeation behaviour. Particular emphasis is placed on structure-property-function relationships, including mass transport phenomena, thermodynamic compatibility between polymers and essential oils, surface charge, wettability, and nanostructure architecture, which collectively influence bioavailability and therapeutic performance. By integrating concepts from polymer physical chemistry, colloid and interface science, and drug delivery kinetics, these sustainable nanoformulations emerge as promising platforms for acne and sebum control. Overall, essential oil-loaded biodegradable polymeric core-shell systems represent a sustainable and scientifically grounded approach to acne management, although further physicochemical characterization, in vivo validation, and consideration of cost, technical challenges, and current limitations are required to support clinical translation.

The paper presents the development of a correlation model for initial tensile elastic modulus for flexible polymers as a function of Shore hardness in OO and A scale based on measurement. Measured polymers are in groups of silicone rubber, nitrile butadiene rubber (NBR), thermoplastic polyurethane (TPU) and silicone. The model is composed of piecewise exponential functions with fixed coefficients chosen to minimize the S₂ error norm and absolute value of relative error at the measured data points. Every chosen section of the hardness scale has one exponential function correlating the hardness to tensile elastic modulus with the argument in the form of a polynomial up to the fourth degree. The coefficients for the polynomial arguments were determined by enforcing interpolation conditions in a chosen set of points in the logarithmic scale for the elastic modulus. The correlation model possesses C0 continuity. For each material, five specimens were used for hardness measurements and five for the elastic modulus testing. The correlation model gives a positive value for elastic modulus of 0 for hardness, and a "finite", "reasonable" value of 100 for hardness and is monotonic. Tensile properties were evaluated using true stress and logarithmic (Hencky) strain, with iterative correction of the changing cross-sectional area to account for large strain. The maximum relative error achieved in the correlation model for the OO scale is 13.4%, while for the A scale it is 7%. The developed model provides a practical and rapid method for estimating the initial tensile elastic modulus from non-destructive hardness measurements and is particularly useful in industrial applications and in the development of material models for dental surgery simulations.

To solve common defects such as warpage deformation, interface debonding, and uneven filling during the two-color injection molding of medical goggles while meeting their multi-performance requirements, including high light transmittance, impact resistance, chemical corrosion resistance, and structural stability, this study conducts research on the process optimization of two-color injection molding. Firstly, based on the principle of material compatibility and Moldflow simulation, a suitable material combination was selected: the first-shot frame adopts Apec 1745 PC material, and the second-shot lens uses Makrolon 2858 PC material, which effectively avoids the risk of interface non-fusion. Subsequently, a high-precision 3D simulation model was established using Moldflow software, and the injection sequence of "frame first, lens second" was optimized and determined. A gating system with double-gate (for the frame) and single-gate side feeding (for the lens), as well as a cooling system with an 8 mm diameter, was designed, and all key indicators of mesh quality meet the simulation requirements. Taking the mold and melt temperatures, holding pressures, and holding times of the two shots as design variables and warpage deformation as the optimization objective, sample data were obtained through an L₃₂ (7⁴) orthogonal test. A BP neural network was constructed to describe the nonlinear relationship between parameters and quality, and the Sparrow Search Algorithm (SSA) was combined to optimize the weights and thresholds of the network, forming a BP-SSA intelligent optimization model. The results show that the mean absolute percentage error (MAPE) of the proposed model is only 2.28%, which is significantly better than that of the single BP neural network (14.36%). The optimal process parameters obtained by optimization are a mold temperature of 130 °C, first-shot melt temperature of 311 °C, second-shot melt temperature of 310 °C, first-shot holding pressure of 83 MPa, second-shot holding pressure of 70 MPa, first-shot holding time of 14 s, and second-shot holding time of 8 s. Simulation and mold test verification indicate that after optimization, the warpage deformation of the goggles is reduced to 0.8956 mm (simulation) and 0.944 mm (measured), with a relative error of only 5.4%, which is 67.9% lower than the initial simulation result. The integrated method of "material selection-CAE simulation-orthogonal test-BP-SSA intelligent optimization" proposed in this study provides technical support for the high-precision manufacturing of thin-walled transparent multi-material medical products.

The regeneration of complex tissues demands advanced scaffolds that offer biomimetic support and tissue-specific bioactive guidance. However, the materials in clinic face big challenges with immune rejection, limited donors, and unsatisfactory inductive activity. Fortunately, cellulose-based scaffolds have risen as a leading sustainable platform, considering their natural abundance, inherent biocompatibility, and highly tunable properties. This review comprehensively presented their evolution from rational design to potential clinical application. The primary cellulose sources and key detailed engineering strategies, including chemical modification, composite formulation, and bioactive functionalization, were arranged logically. The modification of cellulose can tune the physical, chemical, and biological behavior of scaffolds, along with advanced three-dimensional printing fabrication techniques. These material advances have enabled targeted functional outcomes in preclinical models, demonstrating promise for specific applications such as wound healing and bone repair. However, their broad clinical translation is contingent upon resolving persistent challenges, including controlled biodegradation and immune compatibility, which we critically assess alongside emerging frontiers such as smart responsive systems. By bridging material innovation with clinical needs, this review may provide an integrated perspective to guide future cellulose-based scaffold design for tissue regeneration.

Liquid crystalline poly(ester imide)s (LCPEIs) were synthesized by solution polymerization from 4-hydroxybenzoic acid (4-HBA), 6-hydroxy-2-naphthoic acid (HNA) and N-(3-carboxyphenyl)-4-hydroxyphthalimide (3-CHP), with the capping groups of benzocyclobutene (BCB)-containing compounds (BCB-HP for phenolic hydroxyl group and BCB-CP for aromatic carboxylic acid). Subsequent cross-linking of the BCB capping groups upon hot pressing afforded the cured LCPEI films. Optimal properties of these films were achieved by adjusting the capping BCB-HP/BCB-CP contents.These LCPEIs showed favorable thermal properties with a relatively high glass transition temperature (T_g, 137-167 °C) and low melting temperature (T_m, 186-194 °C). With the increase in BCB capping content, the tensile modulus, tensile strength, and coefficient of thermal expansion (CTE) exhibited a non-linear tendency of first decreasing and then increasing. LCPEI-3.0 (3 mol% BCB) showed optimal performance: a relatively low CTE (20 × 10^-6 K^-1), a relatively high storage modulus (2.55 GPa), a moderate tensile modulus (2.65 GPa), a relatively low dielectric constant (Dk = 3.17) with low dielectric loss (Df = 0.0034) at 10 GHz, and excellent hydrophobicity (water contact angle = 133°). This improvement embodies an effective strategy to combine advantages of polyester, polyimide, and benzocyclobutene to achieve favorable and excellent comprehensive properties for convenient processability and practical application prospects.

The exceptional mechanical strength and toughness of collagen arise from its well-defined hierarchical architecture. Conventional methods for obtaining collagen aggregates (CAs), such as direct extraction from native tissues or acid swelling followed by mechanical processing, offer limited control over dimensional uniformity and provide little insight into the underlying exfoliation mechanisms. To overcome these challenges, this study introduces a novel strategy that leverages insights into the hierarchical interactions within collagen. We employ the ionic liquid 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) as an exfoliating agent to successfully isolate fibrous CAs from native bovine tendon. By precisely modulating temperature and processing time, we achieve CAs with tunable mesoscale dimensions (diameter 0.9-1.1 μm, length > 160 μm). Molecular dynamics simulations reveal that [AMIM]Cl disrupts the intramolecular hydrogen-bonding network within collagen, thereby facilitating controlled exfoliation. These exfoliated aggregates serve as fundamental building blocks for fabricating collagen films. The resulting materials exhibit robust mechanical integrity, high transparency, reversible pH-responsive behavior, and excellent biocompatibility as verified by cytotoxicity assays, which together underscore their potential as versatile biomaterial platforms. Furthermore, the integration of single-walled carbon nanotubes yields conductive composites with confirmed electrical functionality. This study thus presents an innovative pathway for the precision processing of collagen and advances the design of high-performance collagen-based biomaterials.