Recently, structural coloring using hierarchical micro-nano structures as a technical field to implement a color without using a chemical colourants and dye is being developed as an attentional technology. The principle of structural coloring is that by the diffraction or multi-interference of light from a material containing a periodic or quasiperiodic structure on the length scale of the wavelength of visible light. For these reason, our research have verified the structural coloring effect on the polymer substrate by fabricate a hierarchical micro-nano structures. Firstly, we have fabricate a nano and hierarchical micro-nano structured mold for verify the structural size effect. Through the replication of structures on the PMMA substrate, we have measured optical properties in the range of visible light. As a results, the surface of nano structured PMMA showed a blue color according to induced the light. Furthermore, color intensity was increased according to increase the aspect ratio and diameter. In contrast, hierarchical micro-nano patterned surface showed iridescent colors.
Anti-Counterfeiting for Polymer Banknotes Based on Polymer Substrate Fingerprinting
