SINGLE-CHAIN POLYSTYRENE GLASSES

The microemulsion free-radical polymerization of styrene generates par ticles containing one or at most a few high molecular weight polymer c hains. Space-filling considerations preclude such chains from adopting their random-coil conformation; rather, they adopt a highly compact g lobular conformation and below T(g) constitute essentially single-chai n glasses. This paper reports apparent spectroscopic and thermal diffe rences between single-chain and conventional multichain polystyrene gl asses. FTIR measurements suggest that the conformational temperature o f the single-chain glasses as prepared is higher than that for multich ain glasses. DSC measurements on these same glasses displayed a first- order exotherm near to the conventional T(g) of polystyrene but therea fter exhibited behavior similar to the multichain samples. The results were explained in terms of the existence of nematic cohesional entang lements in polystyrene glasses.