Synthesis of poly(siloxane/double-decker silsesquioxane) via dehydrocarbonative condensation reaction and its functionalization

•Covalently linked POSS into the main chain of polysiloxane is prepared via dehydrocarbonative polycondensation reaction.•Substitution reaction on the side-chain of polymer enables tunable post-substitution modification reactions.•Highly optical transparency, hydrophobicity, thermal stability and Tg of polymeric films are obtained.

Chlorine-containing poly(siloxane/double-decker silsesquioxane) (P-Cl) was prepared in high yield at ambient room temperature via dehydrocarbonative polycondensation reaction between di[(3-chloropropyl)isopropoxysilyl]-bridged double-decker octaphenylsilsesquioxane (DDSQ) and hexamethyltrisiloxane. Particular attention for this polymer was also given to its functionalization through substitution reaction, especially due to nucleophilic substitution on the side-chain of polymer at silsesquioxane units. But more important, the use of halogen exchange method with bromine anion allows the formation of more reactive, bromine-containing poly(siloxane/double-decker silsesquioxane) (P-Br), which enables further post-substitution modification reactions in a POSS unit. The glass transition temperatures (Tg ∼ 15 °C) of both halogenated polymers were significantly higher than poly(dimethylsiloxane) (PDMS). High transparency of polymers with hydrophobic surface could be found from solvent-casting thin film.

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