Self-assembly And Pore Size Control Of Ordered Mesoporous Silica Particles And Films

As a class of materials characterized by a periodic dielectric function,photonic crystals can regulate light waves in specific directions and wave bands,so they have wide application prospects in the optical field.The periodic structures at the micron or submicron level of the photonic crystal materials were often studied,which are suitable for infrared and visible light bands.However,few studies have been conducted on the photonic crystal materials suitable for short wavelength range which possess ordered periodic arrangement structures at nanoscale.Ordered mesoporous molecular sieves are widely used in the fields of catalysis,adsorption and chemical sensing due to their high specific surface area and uniformly adjustable pore size.Additionally,the unique nanopore structure of mesoporous molecular sieve provides the possibility of using it as photonic crystal materials in short-wavelength range.Based on this research background,a mesoporous molecular sieve structure with hexagonal periodicity arrangement and vertically oriented channels is designed as a 2D photonic crystal film in shortwavelength.By adjusting the mesopore size and filling inside the mesopore channel with conductive polymers,a series of mesoporous silica films with adjustable aperture and cell parameter are obtained,which have important application value as photonic crystals in short wavelength.The research work are as follows:Firstly,the adjustment methods of mesoporous silica pore size and cell parameters were investigated in the preparation process of mesoporous silica particles,and a series of mesoporous silica materials with different cell parameters were prepared,which facilitate the subsequent preparation of photonic crystal film applied to the shorter wavelength range.Mesoporous silica materials were hydrothermally prepared by using dodecyltrimethylammonium bromide as a template,and the effects of different silica sources,alkali sources and p H value on the pore structure of mesoporous materials were investigated.Highly ordered mesoporous silica materials with the unit cell parameter of 3.72 nm and the pore size of 2.25 nm.In addition,decylalkyltrimethylammonium bromide surfactants with shorter carbon chain lengths and adding various auxiliary surfactant as templates were studied,respectively,in order to prepare mesoporous materials with smaller pore size and cell parameter.Moreover,ordered mesoporous silica materials were prepared using self-made gemini surfactants as templates.Secondly,the preparation process of vertically oriented mesoporous silica thin film materials was discussed,and a series of vertically oriented mesoporous silica thin film materials with adjustable pore diameter and controllable thickness were obtained.Herein the electrochemically assisted self-assembly method was used to the preparation of vertically oriented mesopores with different pore sizes and cell parameter by using cation surfactants with different carbon chain lengths(C10/C12/C14/C16/C18)as templates.The surface morphology,channel orientation and ordering of the obtained mesoporous silica film,were characterized by Optical microscope,CV,SEM,HRTEM,etc.In addition,the effective thickness of the films was improved by multiple depositions,and the mesoporous silica films were also prepared by the St?ber solution method.The quality of the films and their surface morphology were compared and analyzed,and the better vertically oriented mesoporous silica films were obtained.Finally,the preparation process of mesoporous channels filled with conductive polymer polyaniline material into mesoporous silica film is discussed,and an ordered polyaniline-mesoporous silica composite film material is obtained.The polyaniline material was grown inside the pores of mesoporous silica film by potentiostatic method to prepare polyaniline-mesoporous silica composite film material.By comparing and analyzing the polarization curves and the cyclic voltammetry curves of the deposited polyaniline film and the composite film on ITO substates,the growth process of polyaniline in the mesoporous pore channel was analyzed.The results showed that polyaniline-mesoporous silica composite film materials having better quality can be obtained,when the time of polyaniline is 150?300 s.