Rapid preparation of crystalline colloidal arrays using a strong electric field dialysis

We present a simple method for rapid preparation of crystalline colloidal arrays (CCAs) by a strong electric field dialysis (SEFD). This method is based on rapid removing of ionic impurities in colloidal suspensions by applying a strong electric field. In a SEFD process, the negatively charged ions in colloidal suspensions are rapidly driven to the anode, the positively charged ones are rapidly driven to the cathode, and the colloidal particles are withheld in the dialysis tube. It was shown that the colloidal particles aggregated on the wall of the dialysis tube could block the SEFD process, which could be overcome by reversing the direction of the electric field. The purified colloidal particles can self-assemble into a crystalline colloidal array, which has an electrostatically stabilized three-dimensional periodic array of colloidal particles with a characteristic lattice spacing that can be varied by dilution. The reflection spectra show distinct peaks due to diffraction from CCAs. Atomic force microscopy (AFM) image illustrates the non-contacted ordering of the colloidal particles in the CCAs embedded in gels. This indicates the formation of high-quality single CCAs. Using a SEFD method, the preparation time of CCAs can be reduced. This new technique will greatly speed up the process of preparing polymerized crystalline colloidal arrays (PCCAs) into real-world application in the analytical field.