Poly(cyclosilane) Postpolymerization Hydrosilylation

Postpolymerization functionalization is a key strategy in the diversification of polymeric materials for the conferral of tailored properties. Poly(cyclosilane)s are structurally complex polymers with an all-silicon backbone, featuring a periodic array of hydrido (Si–H) side chains that are potentially suitable for postpolymerization functionalization via hydrosilylation. At the same time, classical methods for hydrosilylation employing Pt- or Pd-based catalysts can result in Si–Si bond scission. Herein, we demonstrate borane-catalyzed hydrosilylation reactions between α-olefins and small molecules or three distinct poly(cyclosilane) architectures. We investigate chemoselectivity for end group versus internal Si–H groups and find that 29Si cross-polarization magic angle spinning can provide insight on site-selectivity in the functionalization of a complex poly(cyclosilane). We further show that postpolymerization hydrosilylation, converting oxidatively sensitive Si–H groups to Si–alkyl chains, modulates solubility and physical characteristics, optical properties, pyrolytic reactivity, and air sensitivity.