A copolymer of the water-soluble hydrophilic monomer N,N-dimethylacrylamide and of the practically water-insoluble hydrophobic t-butylacrylamide was synthesised in aqueous solution in the presence of sodium dodecylsulfate (SDS) micelles. Its behaviour in dilute aqueous solution was compared to the behaviour of its respective counterpart with practically the same composition, prepared under homogeneous conditions in tetrahydrofuran. The product synthesised under micellar conditions exhibits a pronounced hydrophobic character, as it phase separates in water by increasing temperature at about 46 degreesC, i.e. 29 degreesC lower than the copolymer prepared under homogeneous conditions and associates much stronger with SDS.