Linear siloxane polymers copolymerization

Thus, Andrianov et al. (26) attempted to catalyze polymerization of a number of alkyl and alkyl/aryl cyclosilazanes using catalytic amounts of KOH or other strong bases at temperatures of up to 300°C. In general, the reactions proceed with evolution of NHj, hydrocarbons and the formation of intractable, crosslinked, brittle products even at low temperatures. Contrary to what is observed with cyclotri-siloxanes, no evidence was found for the formation of linear poly-silazanes. Copolymerization of mixtures of cyclosilazanes and cyclosiloxanes gave somewhat more tractable polymers with less evolution of hydrocarbons or ammonia, however very little was done to characterize the resulting materials. 

MAJOR APPLICATIONS Ring-opening pol)onerization of small rings to give linear PPMS high polymers. Copolymerization with other siloxane small rings to give copolymers of controlled composition. 

ADMET polymerization has been used to integrate silicon into linear and network hydrocarbon polymers in an attempt to produce novel materials with enhanced thermal and mechanical stability. While ADMET has been used to produce copolymeric architectures unattainable through conventional methods, application of this polymerization to synthesis is feasible only if the silicon-based functionality does not inhibit metathesis. This research, initiated in the early 1990s by Wagener and colleagues, has shown that the silane and siloxane... 

The base polymers are mainly high-molecular-weight linear polydimethyl-siloxanes prepared by the base- or acid-catalyzed polymerization of cyclic dimethylsiloxanes [(CH3)2SiO—] (see Section 2,A). The copolymerization of methylvinylcyclosiloxanes with dimethylsiloxanes afford polymers with methylvinylsiloxy groups that can be rapidly cross-linked by peroxides such as 2,4-dichlorobenzoyl peroxide or other systems as described in Preparation 2-7. 

---