Synthesis And Colloidal Crystals Assembly Of Monodisperse Polymer Latex Particles

In recent years, photonic crystals or photonic bandgap materials have been an important reaserch field in solid-state physics and material science, because of its potential applications in optical communication functional materials. These materials are made by meso-scale particles (diameter in the range of a few nanometers to tens micrometers), in which the particles are arranged periodically in three-dimentional spaces. Due to the dielectric index of these materials suffers a spatially periodic variation, a band gap will occur when a certain wavelength electromagnetism propagates through its ordered lattice, and some newly photoelectronic properties will be presented, such as restraining spontaneous radiation of atoms and moleculars. It will exhibit greatly potential applications in foundational research and practical applications. One important way to produce photonic crystalsis using colloidal crystals templates made from monodisperse polystyrene and silicone dioxide particles. Various photonic crystals can be obtained through filtering precursor, sol-gel process, and decomposing in high temperature or dissolving in proper solvent.In our study, photonic crystals with such several different constitution as opaline and inverse opaline structure were obtained by using monodisperse polystyrene latex particles modified on the surface. The relative opaline colloidal crystals from colloidal beads were assembled successfully by several different assembly methods, such as vertical deposition, evaporation of the suspension covered with hydrophobic silicone liquid, stepwise spin-coating, evaporation of the suspension under high-humidity conditions (>95%), and natural deposition. And then, the closely packed colloidal crystals were templated into macroporous titania (titanium dioxide) photonic crystals (inverse opaline structure) possessing ordered macropores with pore diameter in the range of a few hundreds nanometers comparable to optical wavelengths.There are three innovations in our study that are as follows:Firstly, hollow polymer latex particles were used to fabricatecolloidal crystals. To the best of our knowledge, there has been still noreport on using hollow colloidal beads to self-assemble colloidalcrystalline arrays up to now. Well-defined polymer colloidal crystalsmade by monodispersed solid colloidal spheres, such as polystyrene beads close-packed in face-centered cubic (fee) or body-centered cubic (bec) structure, have been found applications for photonic band-gap materials. When the spherical polymer beads with uniform size in the 100-1000 nm range are arranged in periodic arrays and planes, and with interplanar separations of tens of thousands nanometers, which are completely identical with the naturally occurring arrays of opals (a class of semiprecious stones), they will show special optical properties in UV (ultraviolet), visible, and near infrared light range. This is because light must pass through two mediums with different refractive index. In our system, these mediums are the polymer beads and air. The periodic dielectric structures can control the propagation of electromagnetic waves by defining allowed and forbidden energy band in the photon dispersion spectrum. In this kind of CCA fabricated by solid colloidal beads, the air just exists in the interspaces of the solid beads. However, to the CCA generated by hollow colloidal beads, as well as the interspaces, the air can exist in the centre of the hollow beads that form the CCA. In this case, the CCA formed by hollow colloidal beads should represent different optical properties compared with those of which formed by solid colloidal beads. Actually, the colloidal crystals made by hollow polystyrene latex particles in our study have presented different optical properties compared with the...