Electrophoretic Deposition Kinetics of ZnO Nanoparticles into an Opal Template and Fabrication of Well-Ordered Macroporous Structure

By a template-mediated process combining an opal template and electrophoretic deposition (EPD) process, a well-ordered ZnO macroporous structure can be formed. The EPD possesses the advantages of low cost and high efficiency. However the main challenge is how to obtain a perfect filling into the interstitial spaces of an opal template with ZnO nanoparticles. Hence it is important to discuss the kinetics of ZnO nanoparticles filling into an opal template at various deposition parameters. Due to electrostatics-induced attraction and the shear stress effect near the boundary layers in the suspension, ZnO nanoparticles are adsorbed onto the surface of the Poly(styrene-co-methacrylic acid) P(St-co-MAA) template during the electrophoretic filling process. This phenomenon results in the nonlinear deposition kinetics of ZnO while filling a template 20 μm thick. After the complete filling of ZnO nanoparticles into the opal template consisting of 300 nm colloids and the subsequent removal of the template, a well-ordered ZnO macroporous structure, a type of photonic crystal possessing an absorptive peak at the wavelength of 560.0 nm, can be obtained.