The size of cooperatively rearranging regions in polystyrene and styrene‐dimethylsiloxane diblock copolymers at the glass transition temperature

Molecular weights of cooperatively rearranging regions (CRRs) in polystyrene and in the styrene microphases of styrenedimethylsiloxane diblock copolymers at the glass temperature are estimated from experimental data of the glass transition published by Krause et al. (Macromolecules 15 (1982) 105). A typical order of 104 is obtained for the samples of high molecular weights. For low molecular weight (< 3 × 104) of the styrene blocks some parallelism between the size of CRRs and the molecular weights of the styrene blocks is observed. A method for discerning between thermal fluctuations and additional microheterogeneities is suggested.