Solvent effect on the self-assembly of colloidal microspheres via a horizontal deposition method

The solvent effect on the self-assembly of polystyrene (PS) colloidal spheres for the fabrication of colloidal crystals (CCs) using the horizontal deposition method was investigated. Solvents containing water and ethanol of different volume fractions were examined. Samples were characterized using scanning electron microscopy and UV-vis-near-infrared spectroscopy techniques. It was found that the surface morphology and local structure of the CCs were significantly affected by the solvent. It was also observed that by adding minute quantity of a tetraethyl orthosilicate sol into the colloidal suspension, well ordered three-dimensional PS CCs without cracks were obtained. Experimental conditions were optimized and high-quality CCs in larger domains were fabricated with PS spheres as big as 2 μm in diameter. The success in fabricating CCs using colloidal spheres larger than 1.5 μm in diameter represents a significant work, especially when applications in photonics and tissue engineering are concerned.