Multihydroxy-Functional Polysilanes via an Acetal Protecting Group Strategy

A new acetal-protected monomer for Wurtz-type coupling to polysilanes, dichloro(3-(2,2-dimethyl-1,3-dioxolane-4-yloxy)propyl)methylsilane, referred to as dichloro(isopropylidene glyceryl propyl ether)methylsilane (DC! MS), has been introduced to synthesize a series of protected linear polysilane copolymers, poly[di-n-hexylsilane-co-(isopropylidene glyceryl propyl ether)methylsilane] (P(DHS-co-IMS)) via alkali-mediated reductive Wurtz-type coupling. The acetal protecting group proved stable under the harsh polymerization conditions. Differential scanning calorimetry combined with H-1, C-13, and Si-29 NMR measurements confirmed composition and random structure of the obtained copolymers. After separation of the cylic fraction, this route yielded defined linear polysilane copolymers with monomodal molecular weight distributions (2000-98700 g mol(-1) (SEC)) and polydispersities in the range 1.61-2.60. Subsequent cleavage of the acetal protecting groups under acidic conditions resulted in the multihydroxy-functional polysilanes poly[di-n-hexylsilane-co-(glyceryl propyl ether)methylsilane] (P(DHS-co-GMS)).