Catalytic hydrosilation of polybutadienes as a route to functional polymers
Abstract
Polybutadienes having a variety of different microstructures have been hydrosilated using HSiMexCl3 –x, x= 0–2 in the presence of H2[PtCl6]. High conversions of double bonds pendant from the main chain are observed but hydrosilation also occurs on the backbone of the polymer especially if there is a high percentage of backbone double bonds. This backbone hydrosilation is accompanied by double-bond migration along the polymer backbone to give conjugated diene units within the polymer backbone. These polymers have been further functionalised by reactions with alcohols [EtOH, EtO(CH2CH2O)2H, 4-hydroxybiphenyl or MeO(CH2CH2O)nH (Mn= 500 or 750)] in the presence of Et3N or by alkylation, e.g. with 2-lithiomethylpyridine or with 6-lithio-2,2′-bipyridine. Polymers containing —SiMex(OR)3 –xx= 2 or 0, R = EtO(CH2CH2O)2H or MeO(CH2CH2O)nH (Mn= 500 or 750) have been shown to form polymer electrolytes, in some cases with room-temperature conductivities as high as 2.5 × 10–5S cm–1. Sequential hydrosilation and epoxidation reactions have been carried out to give polymers in which the pendant double bonds have been hydrosiiated and the backbone double bonds have been epoxidised.