PRODUCTION OF COPOLYMER HAVING THERMALLY REVERSIBLE HYDROPHILICITY/HIDROPHOBICITY

PURPOSE:To facilitate the production of the titled copolymer having a desired transition point, i.e., being soluble or swellable in water in a low temperature region and insoluble in water in a high temperature region, by polymerizing specified two kinds of amide compounds at a specified mixing ratio in a solid phase. CONSTITUTION:N-Isopropylacrylamide is uniformly melt-blended with N-isopropylmethacrylamide by heating them to above the melting points. Then, the melt is solidified by cooling, and the solid solution is irradiated with radiation or electron beams at below the m.p. of the solid solution to effect solid-phase polymerization. The transition point of the produced copolymer lies between those of poly(N-isopropylacrylamide), i.e. 23 deg.C, and poly(N-isopropylmethacrylamide), i.e. 39.5 deg.C, and varies nearly proportionally with a ratio of the two monomers used.