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

Dielectric capacitors composed of polymer-matrix composite films 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/poly-mer 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 1.45x10-3S/cm. The PVDF-based composite with 30wt% BT@PANI loading has high dielectric constants which vary from 31 to 15 in range of 103- 106Hz. 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. © 2024 Cailiao Daobaoshe/ Materials Review. All rights reserved.