Rapid fabrication of crystalline films with double layers and dual members by spin-coating method

Abstract

Ordered colloidal particle films with double layers and dual members could be prepared by stepbystep spincoating method. Monolayer film of larger sized PS or SiO2 colloids was utilized as template to selfassemble second layer of SiO2 colloidal particles with smaller diameter. The size ratio γ of smaller and larger colloidal particles was 0.20—0.56 in the composite films. Larger （L） and smaller （S） dual member colloidal particles formed composite crystalline doublelayer films with multifarious arraymodes, whose structures could be expressed as LSx （here, L represents larger sized particles, S represents smaller colloidal particles, and x represents the stoichiometry of larger and smaller colloidal particles）, and x=1, 2, …, 13. The performance of composite colloidal films were influenced mainly by several factors, including spincoating velocity, spincoating time, viscosity of suspension medium, number density of colloidal suspension, and the wetting properties of substrates, etc.. On the prerequisite of complete wetting between colloidal suspension and substrate, appropriate number density of colloidal suspension, velocity and time of spincoating were the necessary conditions for ordered selfassembling to crystalline film of colloidal particles by spincoating method.