Patent ID: 7820753

Claim:
A method in which a liquid composition comprising an aqueous solvent and a block copolymer, in which the block copolymer comprises a hydrophilic core block and at least two terminal blocks, each terminal block being responsive to a stimulus selected from a change in concentration of ions in the composition, imposition of shear, irradiation with electromagnetic radiation, a change in temperature, and a change in pH, in which the blocks are each formed at least in part by the polymerisation of ethylenically unsaturated monomers, wherein the average degree of polymerization of each terminal block is at least 20 characterised in that the core block comprises zwitterionic pendant groups, and has a degree of polymerisation of about 150 up to about 400 is subjected to a stimulus selected from a change in concentration of ions in the composition, imposition of shear, irradiation with electromagnetic radiation, a change in temperature, and a change in pH, to which the terminal blocks respond, whereby the terminal blocks respond to the stimulus to form a gel.