MICELLIZATION OF POLYSTYRENE-BLOCK-POLY(ETHYLENE PROPYLENE) IN TOLUENE SOLUTIONS OF POLYSTYRENE/

The thermodynamics of the micellization process of polystyrene-block-p oly(ethylene/propylene) in solutions of polystyrene in toluene was stu died. Toluene is a good solvent for both copolymer blocks, whereas pol ystyrene and poly(ethylene/propylene) are not compatible polymers. The influence ofthe polystyrene concentration on the standard Gibbs energ y, Delta G degrees, enthalpy, Delta H degrees, and entropy, Delta S de grees, of micellization was investigated. The thermodynamic magnitudes were calculated from critical micelle temperature and concentration d ata. The critical micelle temperatures ofthe different micellar soluti ons were determined by light scattering measurements. All ofthe standa rd magnitudes of micellization become more negative as the polystyrene concentration increases, suggesting an increment of medium selectivit y.