Coloration of Surfaces With Periodic Microstructures Replicated by Nonisothermal Precision Molding

Abstract Micro/nanoperiodic structures are generally adopted in diffraction gratings. As an important optical component, the diffraction grating has the capability to split and diffract incident white light beams into iridescent beams dispersing to different directions. The appearance of coloration is a form of structural coloration by optical diffraction. In this paper, the nonisothermal precision molding is introduced for rapid and precise replication of periodic micro/nanograting structures, which are employed to render iridescent colors onto surfaces. First, the effect of colorization and periodic grating profiles are theoretically analyzed. Second, different periodic microgratings on silicon wafer, which are generally generated by photolithography, are employed in nonisothermal precision molding process as mold inserts. The molding result indicates that the periodic grating space and depth of grating structures can be precisely replicated from the mold inserts to polymer substrates. Subsequently, the split and iridescent color effects are demonstrated with monochromatic and white incident light beam and compared between samples with different periodic grating spaces. The optical effects of the replicated microstructures confirm the feasibility of this method. The proposed nonisothermal precision molding process provides an alternative manufacturing option for realizing structural colors with large volume and low cost.