Photo and Thermo Responsive Poly-N-isopropylacrylamide Gel

Hydrogels composed with poly (N-isopropylacrylamide)-co-Spiropyran acrylamide (PNIPAM-co-SP) were studied for their photo and thermal responsive properties. A mixture of a certain amount of N-isopropylacrylamide monomers, spiropyran acrylamide, crosslinker N, N$'$-methylene-bis-acrylamide, and photo initiator in acetone/ water solvent was irradiated by UV light to synthesize this PNIPAM-co-SP hydrogel. PNIPAM-co-SP hydrogel was then balanced in water for two days and its property measured by using UV-visible spectroscopy. It is found that the gel's size and charge may be altered using stimuli including light of different wavelengths and temperature.