Chinese Journal of Polymer Science最新文献

Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials. In this study, four linear low-density polyethylenes (LLDPEs) with comparable molecular weights but different short-chain branch (SCB) contents (ranging of 5–66 per 1000 carbon atoms) were modified via dynamic melt mixing using 2 wt% benzoyl peroxide at 145 °C and 50 r/min for 30 min. The influence of SCB content on the processability and structure of the resulting products was systematically investigated. All modified products exhibited good melt processability with melt flow rates (MFR) ranging from 0.46 g/10min to 1.07 g/10min. Products derived from low-SCB LLDPEs showed a lower MFR, higher cross-linking content, a larger number of long-chain branches, and a higher degree of benzoyl grafting. In contrast, those produced from high-SCB LLDPEs exhibited improved processability, reduced cross-linking, fewer long-chain branches, and lower benzoyl grafting levels. A detailed structural investigation of the soluble and insoluble fractions, which were separated using trichlorobenzene fractionation, was conducted to analyze the structural features of various modified products and demonstrate that the SCB content (i.e., tertiary carbon density) significantly influences radical coupling during dynamic modification. Elevated tertiary carbon density, by introducing greater steric hindrance, suppresses radical coupling during dynamic modification, thereby reducing the efficiency of both crosslinking and peroxide fragment grafting. These findings provide new insights into the structure-reactivity relationships in peroxide-induced polyethylene modification and lay the foundation for tailoring material properties via dynamic processing.

This study integrates experimental investigation with molecular dynamics simulations to elucidate the hydrogen transport mechanisms in polyetheretherketone (PEEK) and polytetrafluoroethylene (PTFE), offering fundamental insights into the barrier properties of high-performance polymeric materials. Experimental results demonstrate that PEEK exhibits superior hydrogen barrier performance compared to PTFE at both ambient and elevated temperatures. However, detailed molecular dynamics simulations uncover a distinctive, enthalpy-driven “high solubility-low diffusivity” transport mechanism: although PEEK displays higher hydrogen solubility due to its stronger thermodynamic affinity, its diffusion coefficient is markedly lower than that of PTFE. This mechanism remains operative across a broad operational temperature range (233 K to 358 K), yet its influence on overall permeability is strongly temperature-dependent. At room and high temperatures, the exceptionally low diffusivity of PEEK governs the entire permeation process, establishing its effectiveness as a high-performance hydrogen barrier material. In contrast, under low-temperature conditions (e.g., 233 K), the general suppression of diffusion allows the high solubility of PEEK to dominate, resulting in greater overall permeability than PTFE and giving rise to a performance “reversal” phenomenon. This distinct transport behavior originates from the strong non-covalent interactions between hydrogen molecules and the aromatic rings as well as polar functional groups present in the amorphous regions of PEEK, which simultaneously enhance solubility and impose significant kinetic energy barriers. The “structure-mechanism” correlation framework established in this work provides a robust theoretical foundation for the rational design of next-generation hydrogen barrier materials tailored to specific operational temperature requirements.

The development of intrinsically conductive piezoresistive sensors with high strain tolerance has garnered significant interest. While elastomeric polymers exhibit excellent strain capabilities, their utility in sensing applications has been limited by inherent challenges such as high electrical resistivity, poor aging resistance, and interfacial incompatibility. To address these limitations, hydroxyl-terminated polybutadiene (HTPB)-based polyurethane was chemically modified with acetylferrocene-polyaniline conductive moieties to enhance charge transport properties. Remarkably, this covalent functionalization endowed the resulting ferrocene-polyaniline hybrid polyurethane (FPHP) with a conductivity of 2.33 nA at 1 V bias while preserving piezoresistive functionality. The FPHP demonstrated exceptional mechanical-electrical performance, achieving 254% elongation at break with strain-dependent gauge factors of 7.28 (0%–12.5% strain, R²=0.9504) and 19.66 (12.5%–35.0% strain, R²=0.9929). Further characterization revealed a rapid 0.60 s response time and stability over 3500 strain-release cycles at compression strain, underscoring its durability under repetitive loading. The FPHP sensor was capable of monitoring various human movements and recognizing writing signals. These advances establish a materials design paradigm for fabricating flexible sensors that synergistically integrate high deformability, tunable sensitivity, and robust operational stability, positioning FPHP as a promising candidate for next-generation wearable electronics and soft robotics.

Poly(vinyl chloride) (PVC) materials are produced with high smoke and toxic gases during combustion, when commercial flame-retardant additives are incorporated. Here, rare-earth yttrium stannate (Y₂Sn₂O₇), which is superior to commercial flame retardants, was designed to enhance the smoke suppression and toxicity reduction performance of PVC materials without damaging their mechanical properties. After the addition of 15 wt% Y₂Sn₂O₇ (PVC/Y₂Sn₂O₇), the PVC composites achieved a V-0 rating, whereas the pure PVC material achieved a V-2 rating. The peak heat release rate of PVC/Y₂Sn₂O₇ composite was reduced from 282.7 kW/m² (pure PVC) to 243.6 kW/m². In addition, the maximum smoke density (Ds-max) of PVC/Y₂Sn₂O₇ was 263 m²/m², a decrease of 48.5% compared to pure PVC materials (511 m²/m²), indicating its outstanding ability for smoke suppression. Compared to Sb₂O₃, Y₂Sn₂O₇ can effectively reduce the release of the toxic gas CO (decreasing by 37.5%). Furthermore, the tensile strength of PVC can reach as high as 16.1 MPa. Compared with five widely used commercial flame retardants, Y₂Sn₂O₇ demonstrates superior performance, positioning it as a promising alternative to prospective candidates. Therefore, this study developed a rare-earth flame retardant and offers a promising design to improve the fire safety of PVC composites.

Polymers that exhibit both biodegradability and chemical recyclability offer a promising solution to environmental pollution and resource scarcity. Poly(glycolic acid) (PGA) is a promising chemically recyclable polymer, characterized by its seawater degradability and high mechanical strength. In this study, aliphatic polycarbonates were synthesized through melt polycondensation and subsequently copolymerized with glycolide (GL) to produce chemically recyclable PGA based triblock copolymers with well-defined structures. The properties of these copolymers, including their thermal properties, crystallization behavior, and mechanical performance, can be effectively adjusted by modifying the structure and content of the middle block. Furthermore, an in-depth investigation reveals that the pyrolysis process involves ester exchange, radical, and back-biting reactions. In addition, the high-efficiency “Monomer↔Copolymer” chemical recycling loop has been established, achieving a remarkable yield exceeding 88% along with a purity greater than 99%.

An efficient, simple, and convenient method for Suzuki polycondensation using a diaminocarbene palladium(II) catalyst under aerobic conditions was developed. Reactions between aromatic diboronic acid bis(pinacol) ester and different aromatic dibromides, both with electron-donating and electron-withdrawing fragments in the structure, were carried out. Various reaction conditions, such as the effect of catalyst concentration and solvent, were investigated. The molecular weight characteristics, photo- and electroluminescence properties of the synthesized polymers were studied.

The aim of this study is to develop magnetopolymer composites suitable for fabricating soft magnetoactive robots via extrusion-based 3D printing. Polysiloxane copolymers with urea fragments were synthesized and characterized, and their thermophysical and rheological properties were investigated. This study provides an assessment of the potential for their further use in additive manufacturing. The obtained materials were utilized as matrices for creating magnetically active polymer composites by incorporating microparticles of carbonyl iron. Samples of complex geometries were printed using both neat and filled filaments, demonstrating the feasibility of employing these materials in extrusion-based 3D printing.

Herein, we reported a Tb-carboxyl-imidazole coordination-crosslinked carboxylated nitrile butadiene rubber (XNBR) elastomer design that exhibits high mechanical robustness, fluorochromism, and white-light emission. Imidazole (Im), a toughening, sensitizing, and self-emissive ligand, highly intensified the fluorescence emission, remarkably toughened the elastomer, and imparted multistimuli responsiveness to the elastomer. The Tb³⁺ ions acted as cross-linking centers and provided high-temperature sensitivity of fluorescence emission (more sensitive than Eu³⁺ ions). The as-prepared XNBR/Tb/Im elastomer, with excellent puncture resistance, exhibited an ultimate extensibility of about 3100% and the highest tensile strength of 22 MPa. Experimental and theoretical investigations have demonstrated that Tb³⁺ ions are more likely to interact with Im ligands with increasing amounts of Im. The number of coordination cross-links with higher cross-linking functionalities showed an increasing trend during stretching. The elastomer exhibited an excitation wavelength and temperature-dependent green emission. By introducing redemissive Eu³⁺ into the elastomer, a white-light-emitting XNBR/Tb/Eu/Im elastomer with chemo-fluorochromism was fabricated. The XNBR/Tb/Eu/Im elastomer exhibited stable white-light emission during both heating and stretching. Changing the temperature only resulted in a variation in the intensity of the white light. We demonstrated the potential applications of these elastomers in patterning and information anticounterfeiting/encryption. This coordination crosslinked tough elastomer with fluorochromism and white-light emission paves a new way to fabricate soft devices and sensors, where optical information displays and optical signal responses are required.

The low-voltage plateau capacity, which is highly related to the internal closed pores in hard carbon (HC), is the main contributor to the total capacity in sodium-ion batteries. However, the formation mechanism of closed pores and modification strategies at the molecular level in HC polymer precursors remain poorly understood. Furthermore, the practical applications of HCs are significantly impeded by their low initial coulombic efficiency (ICE). In this study, the intramolecular heteroatom doping (IHP) effect was proposed to facilitate the formation of closed pores in polymer-derived HC for the first time by grafting sulfonyl, ether, and carbonyl groups between benzene rings. As a result, the optimized HC sample showed an increased closed pore volume and low Na⁺ adsorption energy, which delivered a reversible capacity of 307.9 mAh·g⁻¹ and superior rate capability. Through further optimized presodiation, the formed presodiated HC featuring a thin, smooth, and dense solid electrolyte interface film exhibited a remarkably enhanced ICE of 94.4% and enhanced cycling stability (93.6% over 3000 cycles). This study provides an in-depth understanding of the formation mechanisms of closed pores via IHP engineering and develops a new synergistic strategy involving presodiation to prepare highly stable HC anodes.

The poor degradability and limited recyclability of epoxy resins are key challenges hindering the efficient recycling of ex-service wind turbine blades (EWTBs). Herein, we proposed a selective degradation strategy for direct recycling and high-value recovery of epoxy resins by introducing degradable Schiff base groups into the molecular structure and utilizing the resulting oligomers as curing agents. To realize this strategy, a series of Schiff base compounds were synthesized using bio-based vanillin and diamines and subsequently functionalized with epichlorohydrin to yield bio-based epoxy resins. The cured epoxy resins demonstrated remarkable improvements in the mechanical properties of diglycidyl ether of bisphenol-A (DGEBA), with an increases of 44.49% in the tensile strength of 38.55%, bending strength, and impact strength of 71.20 %. The introduction of dynamic Schiff base bonds enabled the selective degradation of the vanillin-2,2-bis[4-(4-aminophenoxy)phenyl] propane-based epoxy resin (VBEP)/DGEBA copolymer, producing 84.20% oligomers that can be directly recycled and reused. Replacing 30 wt% of the curing agent with the oligomer increased the tensile strength of the cured sample to 75.40 MPa, surpassing that of the cured DGEBA. Under simulated acid rain and seawater exposure, the copolymer exhibited a service life of 27 years at 40 °C, significantly exceeding the currently reported service life of 20 years. This study presents a sustainable strategy for the direct recycling and high-value reuse of epoxy resin, offering a promising solution for EWTBs.