Preparation and properties of polysilmethylenes: use of various compounds of group VIII metals as catalysts

High molecular-weight poly(dimethylsilmethylenes) have been prepared by the catalytic polymerisation of 1,1,3,3-tetramethyl-1,3-disilacyclobutane; di-µ-chloro-dichlorobis(alkene)diplatinum(II) compounds proved to be the most reactive of several catalyst systems studied. The molecular weight of the polymer could be controlled by the addition of small amounts of alkyl silicon hydrides or carbon tetrabromide, and the polysilmethylenes then contained Si–H or Si–Br groups. Poly(dimethylsilmethylene) gums were converted into a new type of rubber.