INFLUENCE OF POLYMERS ON THE MICELLIZATION OF CETYLTRIMETHYLAMMONIUM SALTS

The critical micelle concentration values and aggregation numbers of cetyltrimethylammonium bromide (CTAB) micelles have been measured in the presence and absence of the polymers poly(vinyl methyl ether) (PVME), poly(propylene oxide) (PPO), poly(ethylene oxide) (PEO), and poly(vinylpyrrolidone) (PVP). Association of the micelles with the polymers PVME and PPO is apparent from a reduction in both the cmc and the aggregation number. PEO and PVP do not influence these properties. The influence of PVME on the transition from spherical to rodlike micelles of cetyltrimethylammonium tosylate (CTATs) has been studied by measuring viscosities. The shift to higher concentrations of the sudden viscosity increase in the presence of PVME is interpreted as resulting from the formation of spherical, polymer-bound micelles in preference to rodlike micelles. A similar interpretation applies to the transformation of a viscous and non-Newtonian solution of CTAB/sodium salicylate (NaSal) into a waterlike, Newtonian fluid upon addition of PPO or PVME. PVP, ethanol, and 2-methyl-2-propanol do not influence the rheology of a CTAB/NaSal solution, but PEO exerts a modest effect.