Zhiwen Zhu

Poly(vinylidene fluoride) (PVDF) nanofibers hold great promise for self-powered sensing and energy harvesting. However, simultaneously achieving high piezoelectric charge and voltage coefficients and a high electromechanical figure of merit remains challenging because charge generation, voltage output, and dielectric response are intrinsically coupled. Herein, we report a synergistic strategy that integrates negative-polarity electrospinning with grid-controlled corona poling to jointly amplify charge and voltage responses in PVDF nanofibrous membranes. Negative-polarity electrospinning was associated with a higher relative β-phase fraction of 96.28% without markedly changing the overall crystallinity, together with polarity-dependent differences in the near-surface chemical environment. Combined structural, surface-chemical, dielectric, ferroelectric, and piezoelectric analyses suggest that these pre-existing features may influence the subsequent corona-poling response. The enhanced response is discussed within a proposed preconstruction–activation framework, in which corona poling may further align polar domains and introduce charge-related polarization states. Consistent with the proposed coupling between crystal polarization and near-surface charge-related effects, the optimized PVDF(−15) membrane delivers an ultrahigh apparent d33,eff of 264.4 ± 7.9 pC/N, a calculated effective g33 of 7.337 V·m/N, and a calculated effective FOM of 1.9399 × 10–9 m2/N. The resulting device further exhibits high voltage sensitivity to subtle dynamic mechanical stimuli and excellent long-term fatigue resistance, highlighting its potential for diverse self-powered sensing applications. This work identifies electrospinning polarity as a useful processing variable for tuning the device-level electromechanical response of PVDF nanofibrous membranes.

The use of biodegradable plastic foams can alleviate environmental pollution problems caused by the widespread use of petroleum‐based non‐degradable plastic foams. However, fabricating biodegradable polymer foam with a high volume expansion ratio and low shrinkage remains a challenge. In this work, the poly(butylene adipate‐co‐terephthalate)/polybutylene succinate/chain extender (PBAT/PBS/CE) foams with a high volume expansion ratio and low shrinkage were successfully prepared. When the CE content is 0.8 wt%, the stabilized volume expansion ratio of the PBAT/PBS/CE _0.8 foam can be as high as 32, and the shrinkage rate is only 8.6%. Combining FTIR, rheological, and crystallization analysis, it is revealed that the inclusion of PBS increased the rigidity of the PBAT/PBS/CE foaming system, and the addition of CE increased the melt strength of the PBAT/PBS/CE foaming system. As a result of the high volume expansion rate, the compressive strain of the PBAT/PBS/CE _0.8 foam can be as high as 80%. The knowledge obtained from this study provides a method to prepare low shrinkage and a high volume expansion ratio by adjusting the rigidity and melt strength of polymer materials, which will facilitate the practical application of biodegradable plastic foams in the packaging, transportation, and construction industries.

Polyethersulfone (PES) is distinguished by its exceptional comprehensive properties, making it a highly valued engineering plastic employed in various cutting‐edge fields. However, the high cost of PES limits its wider application in industrial fields. Considering the cost‐reduction advantages of polymer foaming, PES foams were successfully prepared in this work using microcellular injection molding (MIM) and micro‐opening microcellular injection molding (MOMIM) foaming methods. Compared with the MIM foaming method, the PES foam samples prepared by the MOMIM foaming method have better microcellular structure and surface quality. As the micro‐opening distance increased, the cell density of the PES foam samples showed a gradual rise before plateauing, with the cell size remaining relatively constant. As a result, the density of the PES foam sample dropped to 1.07 g/cm³, which is 80.5% of the solid PES sample. Meanwhile, the mechanical properties of the PES foam samples remained robust, with both the specific flexural modulus and the specific flexural strength showing increases as the micro‐opening distance increased. The knowledge obtained from this study provides a method for preparing high‐performance PES foam materials, which will facilitate the application of PES in more civilian fields.

Due to similar processing and mechanical properties, poly(butylene adipate‐co‐terephthalate) (PBAT) is expected to be a fully‐biodegradable alternative to low‐density polyethylene (LDPE) packaging films, thereby alleviating environmental pollution caused by waste packaging films. However, the higher price of PBAT limits its large‐scale practical application in the packaging field. Blending with thermoplastic starch (TPS) to prepare PBAT/TPS blends can reduce the cost. In this work, the PBAT/TPS blends with different compositions were prepared using a novel eccentric rotor extruder dominated by an extensional flow field. With increasing the TPS content, a transition from the sea‐island phase structure to the bicontinuous phase structure occurred near the composition ratio of 50/50. Moreover, the dynamic mechanical analysis results showed that the compatibility between PBAT and TPS first improved and then deteriorated as the TPS content increased. As a result, the elongation at break first decreased slightly from ~1585% for the PBAT/TPS(90/10) blend to ~1263% for the PBAT/TPS(70/30) blend and dropped sharply to ~130% for the PBAT/TPS(40/60) blend. The knowledge obtained from this study will help us further understand the effect of the TPS phase on the micro‐morphology and macro‐properties of the PBAT/TPS blends, which is important for the future preparation of high‐performance PBAT/TPS blends.