Super-polystyrene: a new class of engineering plastics with versatile properties

Many attempts to upgrade polystyrene have been made in the past. One of the last and most popular examples is the upgrading of polystyrene by stereo-c ontrolled polymerization of styrene monomer, yielding a syndiotactic materi al. But the property profile of polystyrene can also be improved by stiffen ing the polymer chain with bulky groups. 1,1-Diphenylethylene (DPE) was sel ected as a monomer with such a bulky group and was copolymerized anionicall y with styrene to give an amorphous copolymer with a statistical chain stru cture which was called 'super-polystyrene'. In this paper the conditions of the anionic polymerization and the properties of the resulting materials a re described. Depending on the DPE content, the glass transition temperatur e can be varied from 104 degreesC to 180 degreesC. Up to a DPE content of 1 5%, these styrene-DPE copolymers are miscible with GPPS as well as with syn diotactic polystyrene. Toughening of the transparent polymers was achieved with glass fibers and grafted rubber particles. Block copolymerization with minor amounts of butadiene yielded a tough and transparent polymer. Thermo plastic elastomers with an enhanced softening point having the block sequen ce S/DPE-b-Bu-b-S/DPE and S/DPE-b-EB-b-S/DPE were also prepared.