Preparation Of Monodisperse Polystyrene Latex Particles And Self-assembly Of Two-dimensional Ordered Colloidal Crystal

The ordered 2D arrays of monodisperse latex particles attracted the attention of researchers a long time ago due to their interesting optical properties. When the particle size and spacing are comparable to the wavelength of the illuminating light, a rich variety of optical phenomena, caused by the light diffraction and interference can be observed. Since the lattice constant and the refractive index of the particles can be varied in wide ranges, the optical properties of the arrays can be finely tuned. Colloidal crystals and their reverse structure possess photonic band gaps and light reflection properties, and colloidal crystals of different structure and property can be obtained by modifying and controlling microcosmic structure and surface property, and colloidal crystals possess important scientific meaning and applied value for electrooptic modulator, laser units, biosensors by composite material and non linearity optical material. The premise of the latex ordered colloidal crystals self-assembly is to gain macromolecule latex with even diameter, clear surface and definite mechanical degree.We have prepared monodisperse polystyrene latex by the seeded emulsion polymerization method. In order to process the seeded emulsion polymerization, we prepared seeded emulsion at first by continuous emulsion polymerization. And then we prepare monodisperse, bigger diameter polystyrene latex by seeded emulsion polymerizing. The seeded emulsion and bigger latex are characterized by the laser particle size analytical instrument and TEM. The result indicates the average size and polydispersity of the latex are 95.6nm, 0.047 and 261.6nm, 0.021 separately. The additive mass and the accession rate of emulsifier have both effect on average size and polydispersity of the latex during seeded emulsion polymerizing.At first, the monodisperse latex is dispersed in the ethanol. Two-dimensional ordered polystyrene colloidal crystal is formed by self-assembling in the interface of the cyclohexane-air. And then, the Two-dimensional structure is transferred onto a glass substrate. Then, the two-dimensional ordered polystyrene colloidal crystal is formed by the capillary force. The ordered structure of the two-dimensionalpolystyrene colloidal crystal is characterized by SEM. The result indicates the formed two-dimensional polystyrene colloidal crystal possesses better short-range order and long-range order. The area of the ordered region is larger (mm2). Many factors, for example the concentration and mass of the latex, the average size and the polydispersity of the latex, the clean degree of the glass substrate, have important effects on the order of the polystyrene colloidal crystal. On the basis of preparing two-dimensional ordered polystyrene colloidal crystal, we study the prepared method of the bilayer and the three-dimensional colloidal crystals. The result indicates the order of the bilayer and the three-dimensional colloidal crystal is still better, and the local of the three-dimensional colloidal crystal is short-range order, but the long-range order is worse, and that the ordered region is small. We will further perfect the method of preparing three-dimensional ordered colloidal crystals in future.