Investigation of the conversions of polyorganosiloxanes in the process of thermal polycondensation and catalytic polymerization

Abstract

1. The structural difference of the oligomers produced by the reaction of exchange decomposition and hydrolytic polycondensation was confirmed by the method of IR spectroscopy. In the process of thermal and catalytic transformations, these differences are smoothed out, and the polymers are close in structure, independent of the method of production of the original oligomers. 2. It was hypothesized that thermal polycondensation takes place with the formation of oxygen bridges among the molecular chains on account of condensation of hydroxyl groups and hydrocarbon bridges as a result of the oxidation of the methyl groups of the neighboring molecular chains; the ratio between these two processes is determined by the composition and structure of the oligomers. 3. Catalytic polymerization, in comparison with thermal polycondensation, leads to the formation of polymers with a lower vitrification point and a broader temperature region of the highly elastic state, which is due to the greater flexibility and mobility of their molecular chains on account of the opening of the cyclic units of the oligomer molecules.