A study of polystyrene‐polyvinylmethylether blends by excimer fluorescence

Studies of interchain excimer interaction in semi‐dilute and concentrated solutions of polystyrene (PS) in a good solvent have been extended to polystyrene/polyvinylmethylether (PS/PVME) polymer‐polymer compatible blends. The constant fluorescence intensity ratio R ≡ IE/IM for blends with a PS content lower than 5 wt.‐%, which is smaller than the value of PS in a dilute solution implies a mixing of PS and PVME chain segments down to molecular level in the compatible blend. The fluorescence intensity has been found to serve as sensitive criterion for phase separation. The cloud point curve for the used PS/PVME system has been obtained showing an LCST at 113°C at ca. 20 wt.‐% PS. It was shown that the one‐phase PS/PVME system is thermodynamically stable at room temperature presumably over the entire concentration range.