Light Induced Phase Transition of Poly(N-isopropylacrylamide-co-chlorophyllin) Gels

ABSTRACT: Transducers that enable the direct utilization of energy derived from sunlight have long been sought after. Such systems could be used as actuators, artificial muscles, separators, switches, sensors, memories, etc. In this paper, some properties of visible light-induced phase transitions of poly(N isopropylacrylamide-co-chlorophyllin) gels are presented, which include the dependence of diameter on the light intensity, the transmittance of light, and the swelling and shrinking kinetics. The phase transitions of these gels can be understood in terms of the increased temperature in the immediate vicinity of polymer chains subjected to local heating due to the absorption and sub- sequent thermal dissipation of light energy. The results are described semi-qualitatively by making use of a simple phenomenological model. A set of the phenomena presented here is one of the ex- amples of how to add intelligence to functional polymer gels using volume phase transition and its related phenomena.