Photocaged poly(N-isopropyl acrylamide) (PNIPAM)s, copolymers consisting of N-isopropyl acrylamide (NIPAM) and N-isopropyl-N-(2-nitrobenzyl) acrylamide, are prepared by free radical polymerization. Upon UV irradiation, the hydrophobic o-nitrobenzyl group is cleaved, which subsequently releases the caged NH group and generates more hydrogen bonds with water. As a result, the lower critical solution temperature of caged PNIPAM can be obtained as a function of the photolysis degree of o-nitrobenenzyl caged amides.