Swelling behavior of hydrophobic association hydrogels prepared from octylphenol polyoxyethylene (7) acrylate and sodium dodecylsulfate

Abstract

Hydrophobic association hydrogels (HA-gels) were successfully synthesized from octylphenol polyoxyethylene (7) acrylate (OP-7-AC) and sodium dodecylsulfate (SDS) and their swelling behaviors were studied. Swelling test indicates that the swelling ratio and swelling rate of hydrogel go down first then go up with increased content of SDS. HA-gels exhibited a special “swelling overshoot” phenomenon because of the dissolution of non-gel compositions and surplus SDS. Diffusion of water molecules or the extension of network chains played a major role in the beginning of swelling process of xerogel. With OP-7-AC content increased, swelling ratio of hydrogel and xerogel increased and the “swelling overshoot” became more obvious. At the beginning of swelling, the gel loss increased sharply and then tended to be constant. The gel loss increased with the increase in SDS and OP-7-AC content. The results indicate that SDS and OP-7-AC contents have great effects on the swelling ratio and stability of HA-gels.