Thermally Responsive Hydrogel Films Studied by Surface Plasmon Diffraction

摘要

Thermally responsive hydrogel gratings were micropatterned and immobilized on a gold coated glass substrate using a photochemical cross-linking and attachment method. The thermoresponsive behavior of hydrogels with different thicknesses was studied in MilliQ water by the surface plasmon diffraction (SPD) technique. The diffraction intensity can be substantially increased by surface plasmon field enhancement. Because of its self-reference property, SPD offers considerable advantages in the characterization of the thin hydrogel film. The real-time kinetic observation of the volume phase transition in thin hydrogel films can be achieved by monitoring the diffraction intensity variation as a function of temperature. Little diffraction intensity of the hydrogel grating was observed in the swollen state while strong intensity peaks were observed in the collapsed state owing to the large change in the optical contrast upon the volume phase transition.