Abstract
Poly (N-Isopropylacrylamide-co-2-hydroxyethyl methacrylate) (P(NIPAM-co-HEMA)) was
synthesized using ultrasonic irradiation in a mixed solvent of water and ethanol without chemical initiator. The
effects of monomer molar ratio and ultrasonic intensity on time courses of molar fraction of NIPAM and
responsive temperature of synthesized polymers were investigated. In the early stage of the reaction, NIPAM
fraction of copolymer was low, that is, the polymerization rate of HEMA is high. This is because the radical
stability of HEMA is higher than that of NIPAM. The relationship between conversion and molar fraction of
NIPAM did not depend on the ultrasound intensity. The lower the ratio of NIPAM, the lower the critical value
(LCST) because HEMA is more hydrophobic than NIPAM. The higher polymerization rate resulted in the higher
LCST. Those results suggested that the composition and responsive temperature of the copolymer can be
controlled by changing the irradiation time and the ultrasound intensity.
