Graft copolymerization of N-isopropylacrylamide on styrene-butadiene-styrene block copolymer

Graft polymerization of N-isopropylacrylamide (NIPA-Am) onto styrene-butadi ene-styrene (SBS) block copolymer using benzoyl peroxide was studied to imp rove the water absorptivity and thermosensitivity of SBS. The influence of various grafting reaction factors on the conversion of NIPAAm and the graft ing percentage of SBS-g-NIPAAm were also investigated in the study. The exp erimental results showed that the conversion of SBS-g-NIPAAm was enhanced a s the monomers of NIPAAm were increased. The maximum conversion of SBS-g-NI PAAm was observed when the molar ratio of NIPAAm to butadiene was 1.25. In addition, increasing the reaction time enhanced the conversion of SBS-g-NIP AAm; the maximum grafting percentage was obtained with a 4-h reaction. The optimal concentration of the initiator was 3 X 10(-4) mol/20 mL of toluene, and the grafting reaction occurred at over 65 degreesC. The test results o f the hydrophilicity of the grafted membranes showed that the hydrophilicit y and thermosensitivity were significantly enhanced by grafting NIPAAm onto SBS. (C) 2001 John Wiley & Sons, Inc.