ZrO_2溶胶的醇盐受控水解-缩聚合成及光散射研究

Preparation of ZrO_2-based Sols via the Controlled Hydrolysis-condensation of Zr(OPr)_4 and Light Scattering Analysis of Their Microstructure

采用一缩二乙二醇(DEG)修饰丙醇锆(Zr(OPr)4)的水解-缩聚过程,在乙醇(EtOH)介质中制备ZrO2基溶胶;借助小角X射线散射和激光动态光散射研究胶体微观结构对合成体系组成的依赖性。结果表明,DEG分子可以通过其端羟基与Zr(OPr)4发生亲核取代而形成稳定的配合中间体,有效抑制Zr(OPr)4的水解-缩聚过程,从而在很宽的组成范围内获得稳定的ZrO2基溶胶。此外,在稳定溶胶对应的组成范围内,随DEG引入量减少或反应H2O量增加,胶体粒子数量增大并形成团簇。受胶粒表面未水解的DEG配体残留的影响,胶粒之间通过表面羟基缩合迅速长大的几率很小。

A series of ZrO2-based colloidal samples have been synthesized via the controlled hydrolysis and condensation of Zr（OPr）4 with diethylene glycol（DEG）as the chelating agent.The microstructure of these colloidal systems and its compositional dependence were characterized by the small angle X-ray scattering（SAXS）and dynamic light scattering（DLS）techniques.Based on the strong retarding effect of DEG on hydrolysis-condensation of Zr（OPr）4,we conjectured that one or more stable chelating rings must be formed through the nucleophilic substitution by the terminal hydroxyls of DEG molecules.This offers the opportunities to obtain stable sols in a wide compositional range.Moreover,the light scattering analysis indicates that,with an decrease in DEG content and/or increase in H2O content,the increasing scattering intensities can mainly be ascribed to the emergence of more primary particles due to the increasing predominance of the hydrolysis-condensation and/or the formation of soft particle-clusters due to hydrogen-bonding and amalgamation of interfacial layers between the primary particles.And the primary particles cannot experience a rapid growth due to the presence of the unhydrolyzed DEG segments on their surface.