Glass transition temperature and β relaxation temperature around chain end of polystyrene determined by site specific spin labeling.

A glass transition temperature, T(g), and a β relaxation temperature, T(β), of spin-labeled polystyrene (PS) having a number average molecular weight (M(n)) of ca. 25 kDa were determined by the microwave power saturation (MPS) method of electron spin resonance (ESR). Spin labeling was selectively carried out at chain ends or midchain segments.