Study on the binding strength of polystyrene photonic crystals on polyester fabrics

Four different polystyrene colloidal microspheres were used to fabricate the photonic crystals on polyester fabrics via vertical deposition self-assembly. The binding strength of the resultant photonic crystals was evaluated by designing and performing the bending and folding test and the washing test. The differences in binding strength among the resultant photonic crystals on polyester fabrics were thoroughly investigated by means of digital camera, three-dimensional video microscope, field-emission scanning electron microscopy, and transmission electron microscopy, and the related mechanisms were profoundly analyzed. It was confirmed that the binding strength of the resultant polystyrene photonic crystals on fabrics is closely linked to their own compactness and the adhesive property between the microspheres and the fabric substrates. In general, the microspheres with softer polymer shell could easily adhere to the yarns, fibers, and their own adjacent microspheres to improve the binding strength between the photonic crystals and the fabrics. Moreover, the softer microspheres can more easily form the compact photonic crystal structure, and the array of the colloidal microspheres with more compactness in photonic crystals could possess better binding strength. However, too compact a photonic crystal structure might make the surrounding medium among colloidal array disappear and form a transparent film with uniform refractive index on fabric surface, leading to the lack of photonic band gap and the related optical properties.