PVP改性氧化硅溶胶的微结构和流变性

以正硅酸乙酯为前驱体,聚乙烯吡咯烷酮（PVP）为聚合物改性添加剂,在碱性条件下制备氧化硅溶胶,通过小角X射线散射测量了改性溶胶的微结构参数,辅以动态光散射观测溶胶颗粒生长,研究了聚合物量、碱催化剂量和水量对溶胶颗粒度、分形特征以及流变性的影响规律.由于PVP链中强极性的分子内酰胺基团和氧化硅颗粒表面的羟基形成氢键,致使溶胶颗粒被聚合物链包裹,严重阻碍了溶胶颗粒的生长,使凝胶时间延长,流变性发生变化,同时对溶胶颗粒的微结构产生影响.

Study of the Microstructure of TEOS-MTES Based Sol by SAXS

Polymer modified silica sols were synthesized by the ammonia catalyzed hydrolysis of tetraethoxysilane with polyvinylpyrrolidone (PVP) as polymer modifier in methyl alcohol.By small angle X ray scattering (SAXS),the microstructure was studied with the assistance of dynamic light scattering(DLS).The dependence of the particle size distribution,fractal characteristics,and the rheology of PVP modified silica sols on the PVP content,ammonia content and water content in sols was analyzed.It is easy to form hydrogen bonds between the surface hydroxyls of silica particles and the negatively charged oxygen atoms of inner amide in PVP molecules,and this holds back the further growth of silica particles.Thus the gelation was retarded and the rheology of the sol was largely modified by PVP.