Structure of Surface-Treated Layer withGlycidoxy-Functional Silane Coupling Agenton Silica Particles

Abstract

Surface treatment of silica particles with 3-glycidoxypropyltrimethoxysilane（ GPTMS） by dry-treatmentmethod was done and the characterization of treated layer by thermogravimetric（ TG） measurement wasinvestigated. For this purpose, the TG curves of treated silica and GPTMS oligomer were compared. The TGcurve of treated silica showed three-steps weight losses. The 1st-step decreased whereas the 2nd- and 3rdstepsincreased with the increase of stored days at room temperature after surface treatment. After the alcoholwashing, the TG curve became only 3rd-step and the quantity of 3rd-step decreased by washing. The oligomerwas prepared by heating of GPTMS/water mixture. After sufficient heating, the TG curve of oligomer showedonly 3rd-step. By comparing of TG curves for treated and oligomer, each step of TG curve for treated silicawas estimated as folloes: The 1st-step is the evaporation of monomeric GPTMS without any interaction withsurface. The 2nd-step is the physisorbed monomeric GPTMS formed hydrogen bonding with surface. The 3rdstepis the chemisorbed and physisorbed silane oligomer and chemisorbed monomeric GPTMS. It was foundthat the comparison of TG curves of treated particle before and after washing is useful for the characterizationand quantification of various adsorption states of silane on particle surface.