BT@PANI核壳粒子的绿色制备及PVDF基复合材料的介电性能

Green Preparation of Core-shell BT@PANI Particles and Dielectric Properties of Poly(vinylidene fluoride)-based Composites

聚合物薄膜介电电容器在新能源汽车、太阳能和风力并网发电与储能等领域具有广泛应用和广阔的发展前景。钛酸钡/聚合物复合材料具有介电损耗低、击穿场强高的特点,是电容器中核心部分高介电有机薄膜材料极具潜力的选择之一。目前,迫切需要解决高极化特性与低损耗难以协同改善的问题。本工作提出以苹果酸同时作为钛酸钡(BT)表面修饰剂和聚苯胺(PANI)掺杂剂,采用原位聚合法制备了BT@PANI核壳粒子,并以此为填料制备了聚偏氟乙烯(PVDF)基复合材料。结果显示,通过苹果酸与盐酸的两步表面改性法,可获得钛酸钡-苯胺阳离子(BT-An^(+))粒子,为此不同苯胺(An)与BT-An^(+)质量比条件下填料产物的核壳结构特征明显。当An与BT-An^(+)的质量比为0.5∶1时产物平均粒径最小,约为450 nm,粒径分布最窄,且电导率为1.46×10^(-3)S/cm。以此为填料,30%(质量分数)填充量的PVDF基复合材料在10^(3)~10^(6)Hz范围内介电常数保持在高值水平,由31仅下降到15,介电损耗在宽的频率范围内低于0.3,不仅表现出优良的频率稳定性,而且在获得较高的介电常数情况下,实现了介电损耗的有效抑制。此外,这项工作极大地降低了无机氧化性酸与有机试剂的使用率,为实现高性能介电复合材料的绿色制备提供了实验指导。

with high dielectric constants have a practical application and prospect in the fields of new energy vehicles,solar and wind power grid-connected power generation and energy storage and so on.Barium titanate/polymer composites,which present low dielectric loss and high breakdown field strength,are the prospective materials used as the core part of the capacitors.Now,it is urgent to solve the problem of the balanced improvement on high polarizability and low loss.In this work,barium titanate@polyaniline(BT@PANI)core-shell particles were prepared by the in-situ polymerization using malic acid as a surface modification agent for BT particles and a doping agent of PANI.Then polyvinylidene fluoride(PVDF)-based composites were prepared.The results show that barium titanate-aniline cationic particles(BT-An^(+))was obtained by two-step surface modification of malic acid and hydrochloric acid,and so the core-shell structure character of all products prepared under various mass rations of An and BT is clear.When the mass ratio of An to BT is 0.5∶1,the average particle size is 450 nm and the distribution is the narrowest.and its conductivity value is 1.45×10^(-3)S/cm.The PVDF-based composite with 30wt%BT@PANI loading has high dielectric constants which vary from 31 to 15 in range of 10^(3)—10^(6) Hz.Meanwhile,the dielectric loss remained less than 0.3 within the wide frequency range.The BT@PANI/PVDF composite presents not only good frequency stability but also effective suppression of dielectric loss under the condition of obtaining high dielectric constant.In addition,this work greatly reduces the utilization rate of inorganic oxidizing acids and organic agents and so provides an experimental guidance for green preparation of high performance dielectric composites.