Synthesis and thermal properties of telechelic alpha,omega-bis anhydride oligosiloxanes

Telechelic oligosiloxanes are obtained either via ring opening polymerizati on of polycyclodialkylsiloxane or via hydrosilylation with a alpha,omega -b is hydrosilane oligosiloxane or via condensation between a alpha,omega -bis hydroxy oligosiloxane and an appropriated chlorosilane. This study investi gates the synthesis of a alpha,omega -bis anhydride oligosiloxane via hydro silylation of bicyclo[2.2.1]hept-5-ene-endo-2,3-dicarboxylic anhydride with alpha,omega -bis hydrosilane oligosiloxane in the presence of a Platinum c atalyst. Using a Pt catalyst induced a long reaction time and especially an important increase of average molecular weight. Another method of synthesi s in two steps was then set up: condensation of exo,5-(dimethylchlorosilyl) bicyclo-[2.2.1]heptane-endo-2,3-dicarboxylic anhydride with alpha,omega -bi s hydroxy oligosiloxane which leads to the expected oligosiloxane, rapidly and quantitatively. Thermal properties have also been investigated alpha,om ega -bis anhydridr oligosiloxane may take part in the synthesis of block co polymers. (C) 2001 Elsevier Science Ltd. All rights reserved.