AGGREGATION MODEL THAT DESCRIBES THE PHYSICAL-PROPERTIES OF THE SODIUM DODECYL SULFATE POLY(PROPYLENE GLYCOL) SYSTEM IN AQUEOUS-SOLUTION/

Micellar ionization degrees, from conductivity measurements, and micel lar aggregation numbers, from steady-state quenching fluorescence of t he sodium dodecyl sulfate/poly(propylene glycol) (SDS/PPG) (MW = 425 a nd 1000) systems in aqueous solution, have been obtained. From the exp erimental results we conclude that small aggregates form on the polyme r chain at a surfactant concentration cl smaller than the surfactant c mc. The aggregation numbers of these aggregates sharply increase with SDS concentration and, at a critical surfactant concentration (c(2)) h igher than the SDS cmc, the aggregates become large enough to incorpor ate the polymer chains into the surfactant micelles, forming SDS/PPG m ixed micelles in aqueous solution, that are similar to the cetyltrimet hylammonium bromide (CTAB)/PPG and surfactant/medium chain alcohols mi xed micelles.