核-双壳BT@TiO_(2)@PDA纳米粒子的制备及其复合薄膜的介电性能EI北大核心CSCD

为改善聚酰亚胺(PI)基复合薄膜界面相容性,达到提高其介电性能的目的,利用钛酸正丁酯的水解反应在钛酸钡纳米粒子(BT)表面包覆水合TiO_(2)。采用聚多巴胺(PDA)进一步包覆改性粒子,制备出具有核-双壳结构的钛酸钡纳米粒子(BT@TiO_(2)@PDA)。利用核-双壳结构形成双重梯度缓冲层,减小高介电钛酸钡纳米粒子和低介电聚合物之间由于介电常数差异造成的电场畸变。通过溶液流延法制备一系列含有不同质量分数的改性钛酸钡/聚酰亚胺复合薄膜(BT@TiO_(2)@PDA/PI)。结果表明:核-双壳结构可以改善钛酸钡纳米粒子在聚酰亚胺基体中的分散性及二者的界面相容性。当填料质量分数为40%时,BT@TiO_(2)@PDA/PI复合薄膜的介电常数κ提高到8.8(1 kHz),约为纯聚酰亚胺的2.7倍,为钛酸钡/聚酰亚胺复合薄膜(BT/PI)的1.4倍。介电-温度和介电-频率测试证实,BT@TiO_(2)@PDA/PI复合薄膜具有良好的温度和频率稳定性。在100 kHz的频率范围内,复合薄膜的介电损耗均小于0.010;当填料的质量分数低于40%时,温度从25℃增加到160℃,复合薄膜介电常数的降低数值均不超过0.6(1 kHz)。

Preparation of core@dual-shell BT@TiO2@PDA nanoparticles and dielectric properties of BT@TiO2@PDA/PI composite films

To improve the interface compatibility, dielectric properties and energy storage density of polyimide(PI)-based composite materials, the core@dual-shell nanoparticles, BT@TiO₂@PDA were obtained via facile solution method using the dopamine to coat on the BT@TiO₂ nanoparticles, which is barium titanate (BT) coated with amorphous-TiO₂, hydrolyzed from tetra-n-butyl titanate (TBT). A series of modified BaTiO₃/PI (BT@TiO₂@PDA/PI) composites with different contents of BT@TiO₂@PDA were prepared through a solution casting film formation method. The results show that the dispersion of nanofillers in the polymer matrix and the interface compatibility between them can be improved by utilizing core@dual-shell nano-structured BaTiO₃. The permittivity κ of BT@TiO₂@PDA/PI composite films with 40%(mass fraction) filler loading increase to 8.8 (1 kHz), which is about 2.7 times higher than that of pristine polyimide, 1.4 times higher than that of pristine BaTiO₃/PI composite films. Temperature-dependent and frequency-dependent dielectric performance tests confirm that BT@TiO₂@PDA/PI composites possess good temperature and frequency stability. In the frequency range of 100 kHz, the dielectric loss of the composites is less than 0.010; when the filler loadings are under 40%, the permittivity of the composites decreases by less than 0.6 (1 kHz) from 25 ℃ to 160 ℃.