MICELLES OF POLYSOAPS

Polysoaps, hydrophilic polymers incorporating m amphiphilic monomers, can form intrachain micelles. The structure of the intrachain micelles, the configurations of the polysoaps, and their modification in the presence of free amphiphiles are analyzed for the high salt, dilute solution limit. The important polymeric parameters are the polymerization degree of the spacer chains joining adjacent surfactants, n, and of the chain as a whole, N. The structure of spherical intrachain micelles is similar to that of free micelles up to n approximate to 10. For larger n the aggregation number decreases because of the crowding of the loops formed upon aggregation by the spacer chains. For n approximate to 400 and above the intrachain micellization may be repressed. The chain dimensions are greatly reduced by the intrachain aggregation. When m less than or equal to p(eq), the equilibrium aggregation number of a single micelle, the chain dimensions are those of a single micelle. In the opposite case the thermodinamically favored configuration is that of a branched structure. The addition of free surfactants results in the formation of mixed micelles once the critical association concentration (cac) is exceeded. The cac is typically much smaller than the cmc of free micelles. The formation of mixed micelles ends when a well-defined saturation concentration is attained. At this point the chain is fully unfolded and the structure of the bound, mixed micelles is essentially that of free micelles. When the polymerized surfactants tend to form cylindrical micelles, the shape of the intrachain micelles can vary with n and with the concentration of free amphiphiles.