Journal of Physical Chemistry B, Vol.101, No.46, 9504-9509, 1997
A Kinetic-Analysis of the Initial-Stages of the Sol-Gel Reactions of Methyltriethoxysilane (Mtes) and a Mixed Mtes/Tetraethoxysilane System by High-Resolution Si-29 NMR-Spectroscopy
Si-29 solution NMR is used to follow the kinetics of the methyltriethoxysilane (MTES) homopolymerization and that of the MTES/tetraethoxysilane (TEOS) copolymerization. Individual kinetic rate constants for the hydrolysis and dimerization reactions were obtained by fitting the concentration curves as functions of time for the different intermediate species. It Was found that the individual hydrolysis kinetic constants for the MTES homopolymerization are greater than those for the TEOS homopolymerization. Using the homodimerization and codimerization kinetic rate constants for the MTES/TEOS copolymerization, reactivity ratios were calculated. These reactivity ratios suggest that the two monomers react to form a random copolymer.