Journal of Applied Polymer Science最新文献

Sulfur-rich vitrimers have attracted increasing interest due to their dynamic covalent networks and potential in sustainable materials. In this work, sulfur-based vitrimer networks were constructed via a two-step strategy by combining hydroxyl-functionalized oligosulfides with epoxy cross-linkers. The oligosulfides, containing dynamic oligosulfide (–Sx–) linkages, were synthesized through the oligomerization of elemental sulfur with cyclic disulfides, followed by cross-linking with bisphenol A diglycidyl ether or diethylene glycol diglycidyl ether in the presence of imidazole. By tuning the type and loading of epoxy cross-linkers, the resulting networks exhibit a wide range of mechanical properties, from rigid thermosets to soft and extensible materials, with tensile strengths up to 12.85 ± 2.73 MPa and elongations at break up to 44.40% ± 5.01%. In addition, these vitrimers demonstrate effective adhesive performance, achieving lap-shear strengths of up to 6.05 ± 0.99 MPa on steel substrates. This work provides a straightforward and versatile strategy for designing sulfur-rich vitrimer materials with tunable mechanical behavior and promising potential in structural adhesive applications.

4D printing, an emerging manufacturing technique incorporating a temporal dimension to enable shape/property evolution under stimuli, has gathered significant interest. However, biodegradable polymers suitable for low-cost fused deposition modeling (FDM)-based 4D printing that simultaneously combine low warpage, balanced mechanical strength, and stable thermal-responsive shape memory performance are still scarce. CO₂-incorporated aliphatic-aromatic copolyesters tailored for low-cost FDM-based 4D printing have not been systematically investigated. This study investigates the FDM process optimization, performance characterization, and 4D printing potential of a novel biodegradable polymer, poly-(propylene carbonate phthalate) (PPC-P). Key FDM parameters were determined as printing temperature 170°C–190°C, printing speed 40–50 mm/s, layer height 0.1–0.2 mm. The raster angle significantly affects mechanical performance: specimens printed at 90° raster angle achieve a maximum tensile strength of 33.1 MPa. Single-edge-notch three-point-bending tests confirm that intralayer bonding (G _fe = 2.62 kJ/m²) is superior to interlayer bonding (G _fe = 1.67 kJ/m²). The high-precision FDM fabrication of PPC-P was successfully achieved. Crucially, the printed specimens exhibit satisfactory thermally responsive shape memory effect: complete shape recovery (R _r reached 96.5%) occurs rapidly in 45°C water bath. This work provides a promising new biodegradable material option for FDM based 4D printing, with applications in temperature sensors and soft robotics.

Polylactic acid/hexagonal boron nitride (PLA/h-BN) thermal conductive composites hold broad application prospects owing to their electrical insulation and biodegradability. However, the conventional twin-screw extruder (TSE) based on shear fields struggles to achieve satisfactory in situ exfoliation of h-BN and tends to induce severe degradation of the PLA. This paper employed novel perturbation ring elements (PREs) to modify a dual-speed nontwin screw extruder (NTSE) based on a chaotic field for the large-scale preparation of high-performance PLA/h-BN thermal conductive composite. The results indicate that compared with TSE, NTSE exhibited shorter residence times and a narrower residence time distribution for the material, while the mixing index was significantly improved, which can achieve significantly better in situ exfoliation, dispersion, and distribution of h-BN in the presence of a lower degradation degree of PLA. Moreover, after the NTSE was further modified with PRE, this phenomenon became more pronounced. Compared with those prepared by TSE, PLA/h-BN prepared via NTSE-PRE exhibited in-plane and through-plane thermal conductivities increased by 26.6% and 16.9%, respectively, alongside intrinsic viscosity and weight-average molecular weight elevated by 21.5% and 20.0%, while the Young's modulus after annealing increased by 11.5%. This work provides a novel approach for the large-scale preparation of biodegradable polymer-based thermally conductive composites.

Impact polypropylene copolymer (IPC) is widely used commercially. Ethylene–propylene blocky copolymer (EbP) boosts IPC compatibility at the interface to realize an excellent rigidity-toughness balance, but the impact of its complex distribution on IPC multiphase properties is rarely studied. In this work, two industrial resins (Samples A and B) with similar flexural modulus but significantly different impact strength were analyzed for chain microstructure and copolymer distribution. Combined atomic force microscopy-infrared (AFM-IR), fractionation, chain-structure, and thermal analyses suggest that an EbP-enriched EP-copolymer interphase is preferentially formed in Sample A. In contrast, the stronger crystallization tendency of B100 (the 100°C elution fraction of Sample B) favors premature microphase separation and redistribution of the EbP fraction before crystallization of the isotactic polypropylene matrix, resulting in ethylene-containing copolymer-rich regions in both the dispersed phase and selected locations within the continuous PP phase. This less interface-confined distribution may weaken the compatibilizing effect of EbP and contribute to the poorer mechanical properties of Sample B. The lower molecular weight (M_w) and ethylene content of B100 facilitate the mobility, rearrangement, and crystallization of propylene segments. This work elucidates how the molecular characteristics and crystallization behavior of EbP influence its interfacial distribution and, consequently, IPC compatibility and toughness.

Amino-modified tetraphenylethylene (TPE), an aggregation-induced emission (AIE) fluorescent probe, was employed to investigate crystallization and phase separation of thermodynamically immiscible biodegradable poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends, whose interfacial and crystalline structures govern macroscopic properties but are hard to visualize via conventional methods. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) reveal that flexible PBAT segments enhance PLA chain mobility and crystallinity, whereas TPE restricts chain motion of both components and suppresses crystallization in neat homopolymers and their blends. Fluorescence microscopy confirms TPE preferentially accumulates in the PLA phase and enriches at the PLA/PBAT interface to form an interphase, enabling direct visualization of phase separation morphology. Thermogravimetric analysis (TGA) shows TPE reduces polyester chain entanglement and lowers the maximum thermal decomposition temperature of both phases. Scanning electron microscopy (SEM) of tensile-fractured surfaces indicates interfacially enriched TPE reduces interfacial tension and improves adhesion, but inhibits the debonding-cavitation toughening mechanism, decreasing tensile strength and elongation at break. Fluorescence intensity positively correlates with blend crystallinity, as rigid crystalline regions confine TPE intramolecular rotation. This work provides an intuitive in situ visualization strategy for correlating interfacial structure, crystallization and, performance of biodegradable polyester blends via AIE probes.

A multifunctional sodium alginate/graphene oxide/copper ion (SA/GO/Cu²⁺) hydrogel was developed as a controlled curcumin delivery system with enhanced physicochemical stability and antibacterial activity. The hydrogel network was formed via ionic coordination between alginate carboxylate groups and Cu²⁺ ions, combined with hydrogen bonding and interfacial interactions involving graphene oxide. Key formulation parameters were systematically optimized, and the optimal hydrogel (4 wt% SA, 0.03 M Cu²⁺, 0.6 mg mL⁻¹ GO, 90 min gelation) exhibited a balanced combination of high swelling capacity, improved water retention, and enhanced mechanical strength. Structural and physicochemical characterization (XRD, FTIR, SEM–EDS mapping, and DSC) confirmed the homogeneous incorporation of GO and Cu²⁺ and the formation of a reinforced, predominantly amorphous network with improved thermal stability. The optimized hydrogel exhibited high curcumin loading efficiency at an initial curcumin concentration of 150 ppm and sustained, concentration-dependent release behavior, which followed an anomalous (non-Fickian) diffusion mechanism. Moreover, the curcumin-loaded SA/GO/Cu²⁺ hydrogel showed pronounced antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa . These results highlight the potential of the SA/GO/Cu²⁺ hydrogel as a multifunctional platform for controlled drug delivery and antibacterial wound dressing applications.

A crown ether-functionalized polymeric composite, PSSS(AA-18C6), was synthesized by γ-radiation-induced polymerization for the selective separation of Eu³⁺ and Co²⁺ from radioactive liquid waste. The composite was prepared by copolymerizing sodium styrene sulfonate and acrylic acid in the presence of 18-crown-6 and N,N′-methylenediacrylamide. Optimum synthesis conditions were obtained at an irradiation dose of 20 kGy and 2 wt% crown ether. FTIR, SEM, and TGA confirmed the successful incorporation of 18-crown-6 into a porous, thermally stable crosslinked polymer network. Adsorption performance was strongly pH-dependent, with maximum uptake at pH 5 and equilibrium attained within 90 min. Kinetic data were best described by the pseudo-second-order model (R ² = 0.99), indicating that adsorption was governed by interactions with the available functional sites. Maximum adsorption capacities reached 115 and 60 mg g⁻¹ for Eu³⁺ and Co²⁺, respectively, demonstrating the superior affinity of the composite toward Eu³⁺. Complete regeneration was achieved using EDTA, confirming excellent reusability. Application to simulated radioactive liquid waste containing ^152+154Eu and ⁶⁰Co resulted in removal efficiencies of 94% and 47%, respectively, demonstrating the potential of PSSS(AA-18C6) as an efficient and selective adsorbent for radionuclide separation and radioactive wastewater treatment.

Biodegradable poly(butylene adipate-co-terephthalate) (PBAT) foams are sustainable alternatives to petroleum-based foams, yet their application is limited by poor resilience and severe post-foaming shrinkage. Herein, we report a facile and effective strategy to fabricate high-resilience, anti-shrinkage PBAT foams by blending with thermoplastic polyurethane (TPU) elastomer and incorporating an epoxy-based chain extender (CE) as a reactive compatibilizer. The epoxy groups of CE react with the terminal carboxyl and hydroxyl groups of both PBAT and TPU, generating in situ graft copolymers that significantly enhance interfacial adhesion. Rheological analysis confirms that the compatibilized blends exhibit effectively improved melt strength and elasticity. Benefiting from the combined effect of TPU toughening and CE compatibilization, the resultant PBAT/CE/TPU foam achieves a ball rebound of 52%, representing a 44.4% improvement over neat PBAT foam, and its 24 h shrinkage is remarkably reduced to just 5.3%. Scanning electron microscopy reveals a homogeneous cellular structure with well-dispersed TPU domains embedded in the PBAT matrix. This work offers a promising route to high-performance biodegradable foams for cushioning packaging, sports footwear, and automotive interiors, where resilience and dimensional stability are critically demanded.