Zhao Xiaofang, Yu Min, Zhang Xining
School of Mathematics, Statistics and Mechanics, Beijing University of Technology, Beijing 100124, China.
Polymers (Basel). 2025 May 7;17(9):1286. doi: 10.3390/polym17091286.
Multi-scale characterization techniques have been employed to analyze the size effect of microstructure on the phase transition behavior and dielectric properties of poly(vinylidene fluoride) (PVDF) films. The results show that oriented amorphous fraction layers are prone to form in the vicinity of the grain boundaries of nano-grained films, while the interfacial polarization and electrostriction effect play a major role. Polar nano-regions are prone to form in micro-grained films, and the maximum fraction of polar crystalline phase and maximal dielectric constant can be achieved due to the balance between the intrinsic effect and extrinsic effect of the material. On the contrary, the extrinsic effect corresponding to interfacial charges greatly influences the phase transition behavior between beta and alpha phases for coarse-grained PVDF films, while the dielectric properties are mainly influenced by the intrinsic electrostatic field and van der Waal interaction of the material. Hence, the dielectric behavior of nano-grained films can be adjusted by the copolymerization technique, that of micro-grained films can be adjusted by both the copolymerization technique and the controlling of microstructure morphology, and that of coarse-grained films can be adjusted by the doping technique.
多尺度表征技术已被用于分析微观结构对聚偏氟乙烯（PVDF）薄膜的相变行为和介电性能的尺寸效应。结果表明，在纳米颗粒薄膜的晶界附近易于形成取向非晶分数层，而界面极化和电致伸缩效应起主要作用。在微米颗粒薄膜中易于形成极性纳米区域，由于材料的本征效应和非本征效应之间的平衡，可以实现极性结晶相的最大分数和最大介电常数。相反，对应于界面电荷的非本征效应极大地影响了粗颗粒PVDF薄膜中β相和α相之间的相变行为，而介电性能主要受材料的本征静电场和范德华相互作用的影响。因此，纳米颗粒薄膜的介电行为可通过共聚技术来调节，微米颗粒薄膜的介电行为可通过共聚技术和微观结构形态的控制来调节，粗颗粒薄膜的介电行为可通过掺杂技术来调节。
