可溶性PI／SiO2纳米复合材料中SiO2微相结构变化的研究

选取可溶性聚酰亚胺（PI）作为有机高聚物基本，通过正硅酸四乙酯（TEOS）在聚酰胺酸（PAA）的N－甲基－2－毗咯烷酮（NMP）溶液中进行溶液－凝胶反应,制备出新型的聚酰亚胺／二氧化硅（PI／SiO2)纳米复合材料，并用UV－Vis-FT-IR,SEM和光子相关法等对其溶胶－凝胶转变过程，二氧化硅微相结构的变化进行了研究，并对溶中粒子间的团聚行为作了进一步探讨，结果表明随着处理温度的升高，PAA逐步亚胺化，同时TEOS水解后的硅烃基（Si-OH)逐步缩合，由线型结构向环状结构过渡，原位生成SiO2凝胶网络，实验结果还发现热处理温的升高对二氧化硅元化粒子的尺寸无明显的影响，而光子相关法结果则表明颗粒表面活性Si-OH的存在是引起团聚的一个重要因素。

STUDIES ON THE MICROSTRUCTURAL EVOLUTION OF AS ILICON OXIDE PHASE IN A SOLUBLE POLYIMIDE／SILICA NANOCOMPOSITES

A new class of soluble polyimide／silica hybrid films or solutions were prepared by the sol-gel reaction staring from tet raethoxysilane(TEOS) in the solution of polyamic acid in N-methyl-2-pyrrolido ne. The hybrid films or solutions were obtained by the hydrolysis-polycondensat ion of TEOS in the polyamic acid solution, followed by heating at 270 ℃. UV-Vis, FT-IR, SEM and photon correlation spectorscopy(PCS) were used to monitor the process of sol-gel transition and the microstructural evolution of a silicon oxide phase in the soluble polyimide／silica nanocomposites. Furthermore, the asp ects of coalescence of inorganic particles in the solutions were also investigated. The result shows that with the raising of curing temperature, the hydrolysis product silanol(Si-OH) begins to polycondense gradually, from linear structure to cyclic structure, till forming SiO2 net work accompanied with imidization of polyamic acid(PAA).