Patent ID: 8822550

Claim:
A temperature-, pH- or salt-concentration-sensitive separation material comprising, as an active ingredient, a thermoresponsive polymer compound as set forth by formula (I) or an addition salt thereof; wherein m represents an integer of 10 or more, n represents a number satisfying 0.4≦n≦1, R 1 represents hydrogen or a substituent as set forth by formula (1), and R 2 represents a substituent as set forth by formula (2): the thermoresponsive polymer compound having a phase transition temperature in the range of 5 to 65° C. in an aqueous solution with a salt concentration of at least 1 mM and a pH in the range of 3 to 10.5; and forming an insoluble phase at a temperature lower than the phase transition temperature and forming a dissolved phase at a temperature higher than the phase transition temperature.