The diffraction behavior of crystalline colloidal arrays formed by poly(styrene-co-sodium styrenesulfonate) particles

Abstract

Colloidal particles were prepared by the surfactant-free emulsion copolymerization of styrene and sodium styrene sulfonate crosslinked with divinyl benzene. The mono-dispersed and highly surface-charged spherical particles self-assembled into three-dimensional crystalline colloidal arrays (CCA) in water. The CCA showed Bragg diffraction in the visible light wavelength range. Two diffraction peaks were observed in the range of 350~1000 nm for the CCAs at various particle concentrations. The two peaks shifted to longer wavelengths upon dilution of the colloids corresponding to increasing inter-particle distance. The red shift was accompanied by a gradual decrease in the intensity for the diffraction peak at the lower wavelength and an increase in the intensity of the peak at the higher wavelength.