Synthesis and thermal properties of telechelic α,ω-bis anhydride oligosiloxanes

Telechelic oligosiloxanes are obtained either via ring opening polymerization of polycyclodialkylsiloxane or via hydrosilylation with a α,ω-bis hydrosilane oligosiloxane or via condensation between a α,ω-bis hydroxy oligosiloxane and an appropriated chlorosilane. This study investigates the synthesis of a α,ω-bis anhydride oligosiloxane via hydrosilylation of bicyclo[2.2.1]hept-5-ene-endo-2,3-dicarboxylic anhydride with α,ω-bis hydrosilane oligosiloxane in the presence of a Platinum catalyst. Using a Pt catalyst induced a long reaction time and especially an important increase of average molecular weight. Another method of synthesis in two steps was then set up: condensation of exo-5-(dimethylchlorosilyl)bicyclo-[2.2.1]heptane-endo-2,3-dicarboxylic anhydride with α,ω-bis hydroxy oligosiloxane which leads to the expected oligosiloxane, rapidly and quantitatively. Thermal properties have also been investigated. α,ω-bis anhydride oligosiloxane may take part in the synthesis of block copolymers.