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

Abstract

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-controlled polymerization of styrene monomer, yielding a syndiotactic material. But the property profile of polystyrene can also be improved by stiffening the polymer chain with bulky groups. 1,1-Diphenylethylene (DPE) was selected as a monomer with such a bulky group and was copolymerized anionically with styrene to give an amorphous copolymer with a statistical chain structure which was called 'super-polystyrene'. In this paper the conditions of the anionic polymerization and the properties of the resulting materials are described. Depending on the DPE content, the glass transition temperature can be varied from 104°C to 180°C. Up to a DPE content of 15%, these styrene-DPE copolymers are miscible with GPPS as well as with syndiotactic 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. Thermoplastic elastomers with an enhanced softening point having the block sequence S/DPE-b-Bu-b-S/DPE and S/DPE-b-EB-b-S/DPE were also prepared.