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 (DCIMS), 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 1H, 13C, and 29Si 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)).