Copper Ion Imprinted Hydrogel Photonic Crystal Sensor Film

An ion-imprinted photonic crystal (IIPC) sensor for visual detection of copper ions was prepared by the combination of ion-imprinting polymer and colloidal photonic crystal (CPC) structure. Monodisperse polystyrene (PS) colloidal nanospheres synthesized by the boiling soap-free emulsion polymerization method were used to prepare the CPC template by the solvent evaporation method. An ion-imprinted polymer based on poly(vinyl alcohol) and chitosan (PVA/CS) is infiltrated therein. The IIPC sensor film was then prepared by solvent-assisted freeze–thaw method while the CPC template was strengthened as the air pores of the template were replaced by PVA/CS hydrogel. The shift of the diffraction wavelength can be directly observed by the naked eye through the color change of the IIPCS according to the concentration change of copper ion. Such sensor film showed good selectivity and sensitivity with a lower detection limit of 10–4 M.