Effect of crosslinking concentration on the micelle formation inside the polymer gel network and mechanical properties of sensitive hydrogel polymer in contact with surfactant solutions

Abstract

AbstractThe variation of the swelling and mechanical properties of crosslinked nonionic poly (N‐isopropylacrylamide) (NIPA) polymer gel immersed in tetradecyl dimethylaminoxide (C14DMAO) surfactant solutions at 0.1M NaCl, synthesized at different crosslinker concentrations was investigated. Also the aggregation behavior of C14DMAO surfactants inside and outside the polymer hydrogels has been studied through solubilization of Sudan III dye. The solubilization experiments indicated that, at the degree of ionization α = 0.5 and 1, the surfactant concentration inside the gel is lower than that outside the gel at low crosslinker concentration. In the case of the nonionic C14DMAO at α = 0, on the other hand, the surfactant concentration inside the gel and outside the gel was almost identical, irrespective of the crosslinker concentration. The elastic modulus, G, of the network polymer gel in contact with the C14DMAO solutions of 5 and 10 mM concentration was larger than that of the water solution irrespective of the degree of ionization (α = 0 and 0.5). This difference in the elastic modulus, G, of network polymer gel may be attributed to the change of the rigidity of the polymer network. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3921–3926, 2004