Thermal and viscoelastic properties of selectively hydrogenated poly(1,1-diphenylethylene-alt-butadiene)

The synthetic utility of 1,1-diphenylethylene (DPE) to produce nearly perfectly alternating copolymers of DPE and vinyl monomers is well-established, but the physical properties of the alternating DPE copolymers have not been well documented. We characterized the thermal and viscoelastic properties of nearly perfectly alternating copolymer of 1,1-diphenylethylene (DPE) and butadiene and its selectively hydrogenated polymers. The entanglement molecular weights of the DPE-butadiene alternating copolymer and hydrogenated copolymers are measured 20 – 22 kg/mol. Interestingly, the glass transition temperatures of the DPE-butadiene copolymers decrease from 120 °C to 100 °C as the copolymer is selectively hydrogenated, and this behavior is opposite to the earlier report on the increasing glass transition temperature of hydrogenated DPE and styrene copolymers.