Polycondensation using hydrosilylation: a tool for preparing tailor-made polysiloxanes with anchoring groups

The synthesis of copolymers composed of dimethylsiloxane segments (DMS) of different lengths, regularly separated by one bisphenol A unit (BPA) is described. This was achieved by performing hydrosilylation of 2,2′-diallyl BPA with hydride terminated polydimethylsiloxanes in the presence of Pt(0) catalyst. The influence of several factors, including the control of the [Si–H]/[double bond] ratio and the protection of the –OH groups, on the molecular weight distribution of the polymers is described. Side reactions, such as the isomerization of the double bond and the O-silylation were studied by ¹H and ²⁹Si n.m.r. As expected, there is a strong influence of the DMS segment length and of the presence of H-bonding interactions on the thermal properties of the resulting polymers.