STRUCTURE AND THERMODYNAMICS OF POLYSTYRENE-BLOCK-POLY(ETHYLENE PROPENE) MICELLES IN SELECTIVE SOLVENTS

The concentration and temperature dependencies of micelle formation by a polystyrene-block-poly(ethylene/propene) copolymer in several keton es (2-butanone, 3-pentanone, 4-methyl-2-pentanone, 4-heptanone, 5-meth yl-2-hexanone and 5-methyl-3-heptanone) were studied by static and dyn amic light scattering, viscometry and size exclusion chromatography. N o micelles were detected in solutions of 5-methyl-3-heptanone. The sta ndard Gibbs energy, DELTSAG-degrees, the standard enthalpy, DELTAH-deg rees, and the standard entropy, DELTAG-degrees, of micellization were estimated. The values of DELTAG-degrees and DELTAH-degrees were negati ve for all ketones studied and depended on the polar character of the ketone. The micelles showed larger association numbers and densities i ndependent of the ketone. Micelle dimensions hardly depended on the ke tone.