Assembly And Properties Of Colloidal Crystals On Patterned And Curved Substrates

Colloidal crystals (CCs) formed by assembling with spherical colloidal particlescan serve as potential photonic crystals and template for photonic crystals preparation.Potential far-ranging applications in a variety of fields have been found, such asoptical waveguide, invisible cloak and preparation of three-dimensional orderedmacroporous material. Thus, they have gained considerable attention. However, therealization of prospect applications has strict requirements on the quality, internalstructure, external morphology and optical properties of CCs. Unfortunately,assembled on the common substrate tends to form simple CCs. The preparation ofthese complex CCs relies on a specific substrate. In this dissertation, research wascarried out from assembling CCs on the patterned and curved substrates. The maincontent and results achieved in this dissertation are summarized as follows:1. We theoretically analysed that the stable transfer condition was conducive toforming high-quality CCs with fluid mechanics, firstly. Then, patterned substrateswere used to construct two typical transfer conditions for assembling silica (SiO2) andpolystyrene (PS) colloidal particles to verify the theoretical analysis. The resultsrevealed that although density, thermal stability and the surface charge of the twokinds colloidal particles were different, but the stability of the transfer was importantto gain high-quality CCs. It was in good agreement with the theoretical analysis.2. Colloidal particles assembled on the patterned substrates with differentperiodicity strips to prepare CCs. The difference of stop bands of different materialsand periods defect layers had been studied. Photoresist defect layer compared withair-core defect layer showed a blue shift, the shift value decreased with the increasingof defect layer period.3. Defect layer was inserted in hetero CCs by means of patterned substrates withperiodicity strips via multi-step method. The hetero CCs with artificial periodicityair-core defect showed grating diffraction phenomenon. The defect layer caused CCs layer a shift, but there was no obvious change for CCs layer without defect. The stopband showed a slight blue shift after being composited.4. CCs strips were prepared via colloidal particles assembled on the curvedsubstrates with radius of the centimeter level. The formation of CCs strips neededthree stages, i.e., the formation of wet annular CCs-the water evaporation of wetannular CCs-the cracking of annular CCs, was put forward for the first time bycombining bending deformation theory. The impact factors, such as curvature radius,suspension concentration and evaporation rate, for quality and width of CCs strips hadbeen investigated carefully. The bigger curvature radius of substrate, the poorerquality of CCs strips and wider width. The quality of CCs strips was not affected bythe suspension concentration; the bigger concentration, the wider width. The fasterevaporation rate, the poorer quality of CCs strips; the faster evaporation rate, thethiner CCs strips within certain realms.