Porous styryl-linked polyhedral oligomeric silsesquioxane (POSS) polymers used as a support for platinum catalysts

Abstract

Polyhedral oligomeric silsesquioxanes (POSSs) are prevalent building blocks for the fabrication of siloxane-organic polymers. Organic linkages between POSS units determine the nanoporous structures and potential applications of POSS-based materials. Herein, we synthesized styryl-linked POSS polymers via mild hydrosilylation polymerization reactions of octasilane POSS (POSS-SiH) with aromatic alkynes. The effects of the alkyne monomers and molar ratios of [Si–H] to [CC] on the linkage structures were investigated. It was found that rigid styryl linkages and a high crosslinking degree facilitated the formation of permanent nanopores. We then optimized a binary porogenic system composed of toluene and polyethylene glycol to introduce macropores, producing a hierarchically porous polymer. Taking advantage of styryl linkages that provide a delocalized π-electron environment, the polymer was employed to support platinum catalysts via π-coordination interactions. The Pt@polymer composite exhibited a comparable catalysis efficiency with the commercial Pt(dvs) for a hydrosilylation reaction. More strikingly, this performance of Pt@polymer was maintained after multiple cycles of use. This work not only demonstrates the importance of linkages for constructing porous polymers, but also proves the feasibility of loading metal catalysts on polymers via metal–π interactions.