COPOLYMERS OF ACRYLAMIDE/N-ALKYLACRYLAMIDE IN AQUEOUS-SOLUTION - THE EFFECTS OF HYDROLYSIS ON HYDROPHOBIC INTERACTIONS

Two copolymers of acrylamide/N-4-ethylphenylacrylamide have been prepared by an aqueous micellar copolymerization technique with two different amounts of an anionic surfactant (sodium dodecyl sulphate). Such changes in the polymerization medium give copolymers with different microstructures. Samples of each copolymer were subsequently hydrolysed to 10, 20 and 40% completion. Hydrophobic interactions of all the samples in aqueous solution were then studied in the semi-dilute concentration range near to and above the chain overlap concentration, c*, via rheological and fluorescence techniques. The samples were each studied as a function of concentration, salt concentration, surfactant concentration and temperature. In all cases, the rheological and the fluorescence data were consistent and directly related to the number of interchain liaisons in solution. The number of interchain liaisons increased with increase in the copolymer hydrophobicity and were hence related to the hydrolysis level and the blockiness of the copolymer.