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F. Guida-Pietrasanta

"Hybrid” silicones - an overview on polysilalkylene or polysilarylene

siloxanes fluorinated or not

Polimery 2006, No 2, 104




Summary

This overview on polysilalkylene or polysilarylene siloxanes fluorinated or not, so-called "hybrid” silicones reports the main synthetic routes to obtain these polymers together with the properties of the different polymers. Two routes are presented in more detail: - synthesis of α,ω-bis silanol monomers (prepared either via an organometallic route or via hydrosilylation of α,ω-dienes) followed by polycondensation of these bis silanols; - polyhydrosilylation of a,w-dienes by α,ω-dihydrooligosiloxanes. This new class of polysiloxanes has been developed, mainly since the 1970s, to avoid the possible depolymerization observed under certain conditions (acid or base, medium or high temperature) for classical polysiloxanes. The elastomers prepared by crosslinking of these inorganic-organic hybrid polymers exhibit very high thermal stability and rather low temperature flexibility, and depending on the nature of their backbones or of their side chains, they may be resistant to solvents or fuels. They may thus find applications in advanced technological areas (aerospace, defense, computer applications).


Key words: polysilalkylene siloxanes, polysilarylene siloxanes, polycarbosiloxanes, fluorinated polysiloxanes, hydrosilylation, polycondensation


F. Guida-Pietrasanta

"Hybrid” silicones - an overview on polysilalkylene or polysilarylene siloxanes fluorinated or not