Polymerized Crystalline Colloidal Array Incorporated with Silver Nanoparticles

An intelligent polymerized crystalline colloidal array (PCCA) with relatively broader band gap was prepared. The PCCA was prepared by embedding monodisperse crosslinked spherical polystyrene colloids, which self-assemble into crystalline colloidal arrays (CCA) and diffract light in the UV-Vis region, into the 250 μm thick polyacrylamide hydrogel film partly crosslinked by disulfide. The groups of thiol were attached to the matrix of the PCCA via the cleavage of the disulfide in the aqueous solution of dithiothreitol (DTT). Upon applying the Ag⁺ solution to the PCCA with thiol groups, the Ag⁺ will be attached to the polyacrylamide chain. After the in-situ reduction of the Ag⁺ with NaBH₄, the silver nanoparticles with the diameter of ∼10 nm were incorporated into the PCCA. Because of the relatively lower refractive index of the silver nanoparticles within the visible spectrum, the average refractive index of the PCCA was reduced and the refractive index contrast between the polystyrene particles and the matrix was increased, which resulted in the blue shift of the photonic band gap and the relatively broader band gap.