| Abstract
| - Molecular homogeneity frequently plays a decisive role in the effective application oforganically modified silicate copolymers, but direct characterization methods are not always available orconvenient. We present an alternative tool for determining kinetic parameters for alkoxysilane hydrolyticcopolycondensation using a semibatch reactor with varying time of injection of one component. Allnecessary kinetic parameters are determined from a series of ordinary 29Si NMR data in a straightforwardcase study: copolymerization of dimethyldiethoxysilane and trimethylethoxysilane. As further validationof the rate coefficients, the results of a new series of experiments (varying the monomer ratio) aresuccessfully predicted by the semibatch copolymerization model. With this model, we explore optimizingthe molecular homogeneity of the copolymer products. Even for this relatively simple system, the optimalinjection time is a complex function of residence time, but early injection of the faster-condensing monomergives the best homogeneity at long residence times.
|
