Cage-Like Precursor Formation From Extensive Cyclization in Sol-Gel Inorganic Condensation Polymerization.
Abstract
In the sol-gel synthesis of silica by the acid catalyzed hydrolysis and condensation of tetraethyl orthosilicate (TEOS), the fractal dimension, density and homogeneity of the gel depends strongly on the reaction conditions such as the pH and water concentration. However 29Si NMR results have shown that gelation occurs consistently at 80% conversion. The 80% gel conversion is very high compared to the 30% predicted by random branching theory. These results suggest that cyclization is strongly favorable, forming, typically, the most compact three-dimensional cage-like precursor of expected diameter around 10A. (jg)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 19, 1995
- Accession Number
- ADA290633
Entities
People
- A. V. Mccormick
- J. Sanchez
- L. V. Ng
- P Thompson
Organizations
- University of Minnesota