Preparation of non-iridescent structural color film based on PSH@PDA microsphere

In this work, poly (styrene/2-hydroxyethyl methacrylate) (PSH) particles were coated with polydopamine (PDA) to prepare PSH@PDA microspheres, which mixed with agarose (AG) to fabricate non-iridescent photonic crystal (PC) structural color films via ambient-temperature evaporation self-assembly. Then, the film was coated with a waterborne polyurethane (WPU) layer to enhance the mechanical strength of the films. The effects of the key parameters on the formation of non-iridescent structured color films were investigated. FT-IR and XPS prove that PDA was coated on the surface of PSH. As a black light absorbing material, PDA absorbed stray light and improved the color saturation. PC films with different colors were fabricated through varying the size of PSH template microspheres. The results showed that the optimal PSH@PDA microspheres were obtained as the mass ratio of dopamine (DA) to PSH at 0.5 and the reaction time of 15 h. AG was introduced in the PC film strengthen the adhesion and enhance the mechanical properties of the structural color films owing to a hydrogen bonding network formed between AG of -OH and PDA of -NH. The uniform and bright non-iridescent PSH@PDA/AG structural color film was obtained by mixing a 5 wt% PSH@PDA dispersion and a 0.5 wt% AG solution at a volume ratio of 1:1. Water contact angle measurements, cross-cut adhesion tests, pencil hardness tests and reciprocating friction experiments demonstrated that the PSH@PDA/AG-AG/WPU film exhibited a good water resistance and mechanical strength. This work laid a foundation for large-scale applications in coatings fields.