Preparation of telechelic polysilylenes:: A general methodology for the synthesis of polysilylene-based triblock copolymers

Telechelic polysilylenes have been developed involving the chemical degradation of poly(di-n-hexylsilylene) with bromine. The molecular weight of the newly formed telechelic PDHS depends on the ratio of bromine to the starting PDHS. The percentage of end groups increases as the molecular weight of the telechelic PDHS is lowered, reaching a maximum of 99% difunctionality. Polystyrene-PDHS-polystyrene triblock copolymers have been prepared by coupling polystyryllithium to the telechelic PDHS in the presence of cryptand [2.1.1]. The effect of molecular weight on the disordering transition of PDHS into a columnar mesophase has been studied, and temperature and enthalpy have been shown to decrease by the presence of the PS end groups and eventually became unobservable at high fractions of PS. The morphologies of the triblock copolymers were studied by atomic force microscopy.