MICELLIZATION PROCESS OF DIBLOCK COPOLYME R IN BINARY-MIXTURES OF THETYPE - SELECTIVE SOLVENT GOOD SOLVENT AND SELECTIVE SOLVENT PRECIPITANT

This paper shows the results obtained for the micellization process of polystyrene-block-poly(ethylene/propylene) in 4-methyl-2-pentanone/2- chlorobutane and 5-methyl-2-hexanone/2-pentanol binary mixtures. 4-met hyl-2-pentanona (MIBK) and 5-methyl-2-hexanone (MIAK) behave as select ive solvent for the PS block copolymer, while 2-chlorobutane and 2-pen tanol are a good solvent and a precipitant of both copolymer blocks. F rom classic light scattering measurements as a function of temperature different thermodynamic magnitudes have been obtained It has been obs erved that at constant temperature, the critical micelle concentration increases with the percentage of 2-chlorobutane. A opposite behaviour has been obtained employing 2-pentanol. Using classic and dynamic lig ht scattering and viscometry the micellar structure has been character ized. Micellar size remains constant whereas the association number va ries, decreasing as the 2-chlorobutane increases and increasing as 2-p entanol porcentaje increases in the binary mixture.