To obtain a copolymer which is a heat-sensitive and reversibly hydrophilic and hydrophobic polymer having an arbitrary cloud point by constituting it from a plurality of specific kinds of repeating units.
This copolymer has repeating units represented by formula I (wherein R1 is a 1-4C alkyl) and repeating units represented by formula II (wherein R2 is R1), is cross-linked if necessary with at least one divinyl compd. pref. selected from among N,N'-methylenebisacrylamide, N,N'-methylenebis-N- vinylacetamide, N,N'-butylenebis-N-vinylacetamide, and their derivs., and can be used for a heat-sensitive light-screening material or temp. sensor utilizing the cloud point phenomenon, a temp.-dependent water absorbent for a building material, a fuel cell or secondary cell, a chemical carrier, a separating membrane, etc.
YAMAMOTO KAZUYA
ARAI MASAYUKI
HOECHST IND KK