高储能密度聚酰亚胺/钛酸钡/水滑石复合薄膜的制备与性能

Enhanced Energy Storage Performance of Polyimide-based Nanocomposites by Introducing Two-dimensional Nanosheets

利用零维纳米粒子与二维纳米片在聚合物基体中的协同分散,构筑纳米粒子/二维纳米片/聚酰亚胺(PI)三元复合体系,系统研究了零维-二维组合纳米填料对复合材料介电常数、击穿强度、储能密度以及机械性能的影响.结果表明:采用氟碳表面活性剂插层修饰可以将水滑石剥离为水滑石二维纳米片(HT),在此纳米片溶液中分散钛酸钡纳米粒子(BT),并进行聚酰亚胺的原位聚合.在聚合物溶液形成薄膜的过程中,二维纳米片和纳米粒子的协同作用抑制了各自的团聚,改善了2种纳米填料在聚合物薄膜中的分散状况.在所制备的PI/BT/HT复合薄膜中,HT有利于改善BT在PI基体中的均匀分散,提高了薄膜的击穿强度,进而提升了复合薄膜的储能密度.与仅加入20%BT相比,在聚酰亚胺中同时加入2种填料20%BT和1%HT时,击穿强度达到354.4 kV/mm,储能密度达到2.58 J/cm3,分别提高了12.4%和14.6%.因此,在纳米粒子/聚合物复合材料中增加少量二维纳米片就可以显著改善其性能,这种方法有望在更多纳米复合功能材料领域得到应用.

Increasing demands to improve the energy storage density of polymer dielectric materials have spurred the development of polymers with enhanced permittivity and improved dielectric breakdown.The introduction of high permittivity fillers can effectively improve the polymer permittivity,but it is also easy to cause the reduction of breakdown strength,which affected the improvement of the energy storage density of polymer materials.In this study,the polyimide-based nanocomposite films were fabricated via the in situ polymerization with high permittivity barium titanate(BT)nanoparticles and two-dimensional nanosheets exfoliatred from hydrotalcite(HT)as fillers.The permittivity of PI/BT films gradually increased with the increaseing content of BT nanoparticles.However,the breakdown strength decreased significantly with the increase of BT content.Therefore,the energy storage density of PI/BT composite films showed a remarkable decrease.However,with a small amount of two-dimensional nanosheets of hydrotalcite adding to the PI/BT composite films,the breakdown strength of the composites showed an obvious increase trend.The breakdown strength of the PI/BT film conntaining 30%BT increased by 32.8%when only 1%two-dimensional nanosheets were added.The improvement effect of two-dimensional nanometer sheet on the breakdown strength of PI/BT composite material is the same under different BT contents.Therefore,the penetration strength of PI/BT composite film can be effectively improved by adding two-dimensional nanocrystalline sheets,thus increasing the energy storage density.This is due to the fact that two-dimensional nanosheets can effectively improve the dispersion of high content nanoparticles in the polymer matrix,thus improving the properties of composites related to the dispersion of nanoparticles.Experimental results showed that by introducing two different morphology fillers,the permittivity and breakdown strength of PI/BT/HT composite films can be improved.With the addition of 20%BT and 1%HT,the energy storage density of PI/BT/HT composite film can reach 2.58 J/cm^3,which is 14.6%higher than that of the composite film with only 20%BT.This method of simultaneously adding two different morphology fillers such as nano particles and two-dimensional nanosheets into the polymer matrix was expected to be applied in more fields of nanocomposite materials,especially in fields with high content of nano particles.