SYNTHESIS AND PROPERTIES OF POLY[BIS(GAMMA-ETHOXYPROPYL)SILYLENE]

Bis(gamma-ethoxypropyl)dichlorosilane was synthesized by hydrosilylation of dichlorosilane. Polymerization yielded monomodal high molecular weight poly[bis(gamma-ethoxypropyl)silylene] (PDEPS). PDEPS is soluble in alcohols with longer alkyl groups and acetone. Bulk PDEPS exhibits a blue shift of lambda(max) from 362 to 315 nm correlated with the mesomorphic transition occurring at 25-degrees-C. Above 25-degrees-C, PDEPS transforms into a highly mobile columnarlike mesophase. Transition enthalpy, wavelength of the absorption maximum, and Si-29 MAS CP solid-state NMR indicate that PDEPS crystallizes in a disturbed all-trans-like structure. In addition to PDEPS, some copolymers with di-n-hexyl-substituted units were studied.