The Self-assembly Preparation And Application Of Photonic Crystals

Photonic crystals(PCs) can be considered as periodic arrangements of regularly shaped materials with different dielectric constants. It exhibits fascinating Bragg diffraction and bright structural colors owing to the periodic strucrure. Molecularly imprinted technique, having received great attention and becoming a research hotspot, is a well-established and facile method to prepare molecularly imprinted polymers(MIPs) with specific recognizing abilities. Based on the unique properties of PCs and MIPs, combining molecular imprinting with photonic crystals is a promising technique to develop sensor platforms which enable the change in optical properties be transferred into a readable optical signal acompanying a visible color. Here, monodisperse silica nanospheres were synthesised and the preparation conditions were investigated. Then, molecularly imprinted photonic crystal films were prepared via vertical deposition assembly method for selective determination of four phthalte esters and BSA respectively. Detailed information is decribed as follows:1. Monodisperse silica particles with the diameter from 180 to 400 nm were synthesised according to St?ber method with necessary modifications. The preparation conditions such as temeperature, volume of TEOS, volume of ammonia, volume of ethanol were delicately investigated. Then, vertical deposition assembly method was aplied to achieve opal strucure, whose reflection spectra is consistent with the theoretical value determined by the Bragg equation and the simulated value determined by the FDTD simulation.2. With DINP as imprinted molecule, an inverse opal structural molecularly imprinted photonic crystals(MIPCs) sensor was developed and its efficiency on determination of four phthalate esters was investigated. The preparation of MIPCs consisted of self-assembly of monodiperse silica nanospheres, polymerization, etching of silica nanospheres and imprinted molecules. Eventually, the formed MIPCs allowed rapid and sensitive detection of target analytes with specificity. The MIPCs red shifted by 30 nm, 38 nm, 26 nm, 32 nm respectively when soaked in 1mol/L DEP, DBP, DIBP, and BBP methanol solutions. The maximum peak shifts showed a good linear relation with logarithm concentrition. The molecular binding process can be completed within 6 minutes, and the MIPCs exhibited good physical stability and chemical inertness with 5 times reusing.3. In order to overcome or alleviate the problem associated with the mass trasfer difficulty, a promising biosensor affinitive to a protein was performed based on combining photonic crystal and surface molecular imprinting. The process consists of surface imprinting BSA, self-assembly of monodiperse silica nanospheres, polymerization, etching of silica nanospheres. As a proof of this principle, BSA was selected as target analyte. The reflection of surface molecular imprinted PCs red-shifed 21 nm in response to 1.0 mg/ml of BSA, and the maximum peak shifts showed a linear relation with logarithm concentrition, whereas there were no obvious peak shifts for non-surface molecule imprinted PCs.4. In order to quickly prepare photonic crystlas and develop its application in security identification, photonic printing, and optical devices, photonic crystal was obtained via ploymerization-induced colloidal assembly involving forming and growing of colloidal crystals seeds, colloidal assembly and solidification, showing the capability of quickly producing PC films with an ultra-narrow bandgap, tunable thickness, and large size. The impact of the volume of silica nanospheres was investigated, which blue shifted with the increasing of silica volume. The impact of diameter of silica nanospheres on the preparation process was investigated. The application in patterning was successfuly exhibited.