Journal of Polymer Science最新文献

The incorporation of polycyclic moieties and methyl groups into the structure of rigid-chain glassy polymers are two known approaches to improve their gas transport properties. In this study, the combination of these approaches is reported for polynorbornenes. More specifically, the gas transport characteristics of glassy microporous polynorbornenes containing methylated 9,10-dihydroanthracene pendant substituents were systematically studied. These membranes exhibit a combination of relatively high permeability (maximum CO₂ permeability is 1600 Barrer) and good separation parameters (α[CO₂/N₂] up to 41, α[O₂/N₂] up to 4.8) and noticeably better gas separation characteristics compared to analogous polymers without Me-groups. The results obtained indicate that methyl groups positively influence the gas separation performance of glassy polynorbornenes when they are rigidly bonded to the main polymer chains, even through polycyclic moieties. This effect appears to strengthen as the number of methyl groups per substituent increases.

This study addresses the dual imperatives of sustainability and flame-retardant safety in high-performance polymers by utilizing nucleobases—specifically adenine—as renewable biobased monomers for the synthesis of a new series of polyimides. Among the synthesized polyimides, the one derived from the polymerization of the adenine-derived diamine (ADA) with 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), referred to as ADA-6FDA, exhibits outstanding performance, with a glass transition temperature (T _g) exceeding 356°C, a low coefficient of thermal expansion (CTE) of 25.2 ppm K⁻¹, and a remarkable limiting oxygen index (LOI) of 52%. These results indicate that the adenine structure imparts thermomechanical properties comparable to or superior to those of petroleum-based polyimides. At the same time, the high nitrogen content provides an intrinsic flame-retardant pathway through the release of inert gas and the formation of char. This heterocyclic contribution to high flame retardancy is also evidenced by a series of reference polyimides comprising aromatic or isosorbide-based diamines. This work establishes a sustainable class of polyimides that combines high performance with enhanced safety, offering an eco-friendly alternative for advanced electronic and aerospace applications.

In this work, the effects of the interaction between the blowing and nucleating agent content on nucleation efficiency and cell structure were investigated, the growth process of the cells was observed using visualization equipment, and the nucleation process was fitted. The results demonstrated that the addition of ZIF-8 nucleating agent at low blowing agent content (1.5 wt.%) significantly increased the cell density from 5.61 × 10³ to 2.80 × 10⁵ cells/cm³, and the cell size decreased from 372.6 to 86.2 μm. At high blowing agent content (4.5 wt.%), the nucleating agent addition resulted in only a modest increase in cell density, from 2.98 × 10⁶ to 6.61 × 10⁶ cells/cm³. The reduction in cell size was also less pronounced, decreasing from 48.65 to 32.49 μm. Simultaneously, foam samples were prepared using the core-back technology for engineering verification, which exhibits excellent consistency with the visualization observations. Additionally, these results also revealed that the gas concentration was a key factor governing cell nucleation when the nucleating agent content was low. However, the heterogeneous nucleation mechanism played a dominant role under high nucleating agent content conditions, significantly reducing the nucleation energy barrier to enhance nucleation efficiency.

To address the flammability issue of CO₂-based polycarbonate (PPC), this study synthesized a phosphorus-containing flame retardant via the addition reaction of maleic anhydride (MA) and lowly oxidized diphenyl phosphine oxide (DPO), and further prepared a high-phosphorus-content flame-retardant functional CO₂-based polycarbonate material (PPCO) by incorporating this monomer as the third component in ternary copolymerization of CO₂ and propylene oxide (PO). Performance testing revealed that the thermal properties of PPCO significantly improved with increasing content of the phosphorus-containing monomer. Compared to PPC, its 5% weight-loss degradation temperature (T _d,−5%) and maximum weight-loss degradation temperature (T _d,max) increased by 96°C and 93°C, respectively, while the glass transition temperature (T _g) reached 46°C. In terms of mechanical properties, the tensile strength of PPCO increased by 15.9 MPa and Young's modulus improved by 4.3-fold relative to PPC. Most importantly, PPCO exhibited outstanding flame retardancy, achieving a limiting oxygen index (LOI) of 33.9% and meeting the UL-94 V-0 rating (no dripping). This research provides new insights for developing high-performance flame-retardant polycarbonate materials, and PPCO shows potential applications in flame-retardant materials for building exteriors and the electronics industry.

Water-lubricated bearings are prone to severe abrasive wear under low-speed and heavy-load conditions. Therefore, developing ultra-high molecular weight polyethylene (UHMWPE) composites with superior wear resistance is crucial for water-lubricated bearings. Herein, the tribological behavior of a novel UHMWPE/Silicon dioxide/Molybdenum disulfide (SiO₂/MoS₂) composite was investigated through a combined experimental and molecular dynamics (MD) simulation. The results demonstrated that the synergistic effect of SiO₂ and MoS₂ significantly improves the tribological properties of UHMWPE. Compared to pure UHMWPE, the composite exhibits a 62.96% reduction in wear rate and achieves an average friction coefficient as low as 0.044. Furthermore, MD simulations visually reveal the synergistic lubrication mechanism formed at the friction interface due to the structural differences between the two fillers, effectively enhancing interfacial slip between the composite and the counterpart ball.

Herein, we propose an innovative “dual-ion transport channel” (DITC) strategy to overcome the classic trade-off between high ionic conductivity and reduced sensing sensitivity in conductive hydrogels. By incorporating MXene nanosheets and CaCl₂ into a polyvinyl alcohol (PVA) hydrogel matrix, the system simultaneously establishes two continuous conductive networks: an ion-transport channel facilitated by enlarged interchain spacing within the amorphous polymer network, and an electron-conduction pathway through hydrogen-bonded MXene nanosheets. The resulting hydrogel exhibits integrated properties of flexibility, high strain sensitivity (with a gauge factor of 1.96 within 100%–700% strain), and freezing resistance. A further incorporation of aramid nonwoven fabric layer by layer creates a composite with exceptional electromagnetic interference (EMI) shielding performance, achieving a shielding efficiency of approximately 17.8 dB through synergistic dielectric and conduction loss mechanisms. The composite also retains flexibility, flame retardancy, and stable EMI shielding capability under mechanical deformation, highlighting its strong potential for applications in high-performance wearable sensors and advanced protective textiles.

Porous polymers were successfully synthesized via conventional radical polymerization of multifunctional methacryloyloxy phosphate monomers, bis[2-(methacryloyloxy)ethyl] phosphate (BMEP) and phosphoric acid 2-hydroxyethyl methacrylate ester (PHME), in tetrahydrofuran (THF) through polymerization-induced phase separation. Polymerizations of BMEP in various alcohols such as 1-propanol, 1-butanol, and n-hexanol at appropriate monomer concentrations also yielded porous networks. The resulting polymers exhibited monolithic morphologies composed of interconnected spherical particles with diameters of 1–2 μm. These porous monoliths were mechanically robust, showing no fracture under compression up to 50 N, and demonstrated excellent thermal stability, beginning to decompose around 280°C under both argon and dry air atmospheres while leaving 40–50 wt% residues at 500°C. The presence of phosphate groups within the polymer backbone effectively imparted flame retardancy to the materials.