Thermoresponse of poly(acrylamide-co-butyl methacrylate)/polyacrylic acid/MWCNT composite hydrogels observed by infrared irradiation

Abstract

An infrared-responsive poly(acrylamide-co-butyl methacrylate)/polyacrylic acid/multi-wall carbon nanotube (MWCNT) interpenetrating network hydrogel was prepared, and its temperature response was observed. This hydrogel exhibits an upper critical solution temperature (UCST)-type temperature response; it swells at temperatures above the UCST and shrinks at temperatures below the UCST. Gravimetric measurements of the gels revealed that the infrared-induced temperature rise of the MWCNTs and subsequent cooling could be the cause of the recurrent swelling and shrinking. However, the degree of swelling was reduced by the addition of MWCNTs despite their exothermicity.