Borane-catalyzed hydrosilylation for polymer synthesis and heterogeneous catalysis

Abstract

1. Metal-Free Hydrosilylation Polymerization by Borane Catalyst A novel polymerization strategy utilizing metal-free hydrosilylation of dienes with disilanes was developed by using $B(C_6F_5)_3$ catalyst to replace precious transition metal-based systems. The highly reactive $B(C_6F_5)_3$ catalyst enabled a step-growth polymerization with high degrees of polymerization under the easy-to-handle and mild conditions. Diverse polycarbosilanes with a broad range of structures and properties were obtained by various combinations of dienes and disilanes.

2. Borane-Catalyzed Hydrosilylative Post-Modification of Polymers We explored the $B(C_6F_5)_3$-catalyzed deoxygenation reaction of oxygen functionalized polymer. The olefin-containing block copolymer was prepared by deoxygenation reaction of the acrylate block copolymers synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. This novel post-modification method provides a new way to prepare olefin copolymer with highly regulated structure and unprecedented combination which have not been synthesized by conventional olefin polymerization methods.

3. Heterogeneous B(C6F5)3 Catalyst for Hydrosilylative Reduction We developed borane-immobilized carbon nanotubes as the catalyst for hydrosilylative reduction. The heterogeneous borane catalysts are readily prepared via $\pi-\pi$ interactions between $B(C_6F_5)_3$ and the CNT surface. The substrate scope is broad to include carbonyls, acetals, and epoxides with excellent chemoselectivity under mild conditions. Preliminary kinetic studies reveal that the turnover frequency is highly sensitive on the steric bulkiness of both substrates and silanes rather than the electronic effects probably due to the sterically demanding environment surrounding the molecular borane anchored on the surface of carbon nanotubes.