Reactions of 3-glycidoxypropyltrimethoxysilane (GPS) in a water-rich environment with silica colloids were studied. 29Si NMR spectroscopy was used to monitor quantitatively the variation in GPS hydrolysis, condensation, and adsorption with pH and water concentration. The results show the competition between adsorption on the silica surface and condensation polymerization of GPS in the bulk liquid and are used to identify conditions favorable to surface modification. The presence of colloidal silica was shown to increase the apparent GPS dimerization rate, suggesting either surface catalysis or an increased local reactant concentration in the electrical double layer around the silica colloids.
Bibliographical noteFunding Information:
This work was supported by the Center for Interfacial Engineering, an NSF Engineering Research Center at the University of Minnesota. We are grateful for discussions with Dr. Lixin Chu.
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- Silane coupling agents
- Silica colloids