Crystalline colloidal arrays were formed by three-dimensional arrays of monodispersed polystyrene colloidal nanoparticles in suspensions.Then polymerized crystalline colloidal arrays hydrogel photonic crystal films composed of polyacrylamide hydrogels

were fabricated by an in situ photopolymerization of functional monomer acrylamide and immobilized the crystalline colloidal arrays successfully

and the resultant films exhibited bright Bragg diffraction in the visible spectrum.In particular

these hydrogel photonic crystal films showed excellent feature of dehydration-rehydration

and ideal recycling performance had also been proved to be involved in these films inherently.When the fabricated films were immersed in aqueous solutions with the concentration of ethanol ranging from 5% to 30%

the Bragg diffraction peak shift of approximately 20 nm was observed as the concentration of ethanol in hydrous solution changed 5% equally.Furthermore

these films have shown fascinating pH response property after hydrolyzed.The Bragg diffraction peak redshifted with the increase of pH in the range of 2.36 to 8.15.In contrast

with further increase of pH value

the Bragg diffraction peak would blueshift when the pH value increased to 9.6.Specially

color change corresponding to the shift of Bragg diffraction peak of the acquired hydrogel photonic crystal films can be easily distinguished by the naked eye.