Photoinduced phase transition of gels

Equilibrium swelling curves of copolymer gels of N-isopropylacrylamide and a photosensitive leucocyanide, were determined as a function of temperature under UV irradiation. Without UV irradiation the gels underwent a sharp continuous volume change, whereas upon UV irradiation they showed a discontinuous volume phase transition. For appropriate temperatures, the gels discontinuously swelled in response to irradiation of light and shrank when the light was removed