The vertical deposition self-assembly process and the formation mechanism of poly(styrene-co-methacrylic acid) photonic crystals on polyester fabrics

Three-dimensional (3D) photonic crystals with structural colors were successfully fabricated on soft polyester fabrics through the vertical deposition self-assembly of monodispersed poly(styrene-co-methacrylic acid) (P(St-MAA)) colloidal microspheres. The elaborate process was investigated by digital camera, 3D video microscope, and field emission scanning electron microscopy, and the formation mechanism and the self-assembly mode of photonic crystal on the fabrics were proposed. It was confirmed that during the evaporation of the colloidal dispersion medium, the surface of the dispersion moved down slowly, and the photonic crystal structure was deposited gradually onto the fabrics due to two effects of capillary force, one being from the meniscus between the P(St-MAA) colloidal microspheres and the vertical polyester fabric substrate, and another from the liquid bridges between adjacent P(St-MAA) colloidal microspheres. The array of colloidal microspheres underwent a disorder-to-order transition during the formation stage, generating a series of varying structural colors in the process. Different from those on solid nonporous substrates, the vertical deposition process firstly occurred in the gaps of fibers, then in the fiber surfaces, and eventually formed the ordered photonic crystal structure on polyester fabric substrates.