| 摘要 |
PROBLEM TO BE SOLVED: To obtain an N-isopropyl(meth)acrylamide polymer easy in controlling its cloud point, and having a sensitivity to e.g. pH, electric potential or salt concentration, adsorbability or the like by including an N-isopropyl(meth) acrylamide unit and cysteamine unit. SOLUTION: This polymer comprises an N-isopropyl(meth)acrylamide unit of formula I (R1 is e.g. H or a 1-4C alkyl), and a cysteamine unit of formula II or its neutralization salt, and it is obtained by polymerizing an ethylenic unsaturated monomer composition containing an N-isopropyl(meth)acrylamide monomer in the presence of cysteamine. A usage of the cysteamine and its neutralization salt pref. lies in the molar ratio (500 to 1) to (10 to 1) of the ethylenic unsaturated group to the unit of formula II. Furthermore, it is preferable to include a unit of formula III (X is NH or C=O; and R2 and R3 are each a 1-4C alkyl) or its neutralization salt because of enabling the polymer to be imparted with the above sensitivity and a high cloud point while allowing it to keep a function derived from the unit of formula I.
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