Water-soluble cyclocopolymers of N,N-diallyl-N-alkoxybenzyl-N-methylammonium chloride (alkyl = hexyl and octyl) and N,N-diallyl-N,N-dimethylammonium chloride were prepared by free radical polymerization at 50-degrees-C in aqueous solution. The copolymer compositions were determined by H-1 n.m.r. and u.v. measurements. The solution properties of the copolymers were studied as a function of the length and concentration of pendent hydrophobic groups, copolymer concentration and electrolyte or surfactant concentration, utilizing rheological and fluorescence methods. The copolymers in dilute solutions exhibit primarily intramolecular hydrophobic associations in both pure water and electrolyte solutions. The shear-thickening behaviour observed for these copolymer in dilute and semidilute solutions is interpreted in terms of intramolecular and intermolecular associations. Addition of sodium dodecyl sulfate (SDS) to the copolymer solutions results in a large increase in the viscosity at SDS concentrations below the critical micelle concentration. Fluorescence studies suggest that the viscosity enhancement is caused by interpolymer association of polymer-SDS domains.