EXCIMER FLUORESCENCE STUDY ON THE MISCIBILITY OF POLY(VINYL METHYL-ETHER) AND STYRENE-BUTADIENE STYRENE TRIBLOCK COPOLYMER

The excimer fluorescence of a triblock copolymer, styrene-butadiene-st yrene (SBS) containing 48 wt% polystyrene was used to investigate its miscibility with poly(vinyl methyl ether) (PVME). The excimer-to-monom er emission intensity ratio I(M)/I(E) can be used as a sensitive probe to determine the miscibility level in SBS/PVME blends: I(M)/I(E) is a function of PVME concentration, and reaches a maximum when the blend contains 60% PVME. The cloud point curve determined by light scatterin g shows a pseudo upper critical solution temperature diagram, which ca n be attributed to the effect of PB segments in SBS. The thermally ind uced phase separation of SBS/PVME blends can be observed by measuring I(M)/I(E), and the phase dissolution process was followed by measuring I(M)/I(E) at different times.