Mesoporous Materials And Functionality Of Energetic Materials Correlation And Composite,

Ordered mesoporous materials possess quite unique properties,such as high surface area,regularly arranged mesopores with various topologies,tunable pore size, large pore volume and abundant morphologies,which make them show enormous potential applications in catalysis,sorption,separation,sensor,drug delivery,and so on. Nevertheless,it is still far away from practical applications and more work has to be done for this object.Historical review on mesoporous materials demonstrated that it developed and promoted by intercross of disciplines,and this demand further expanding research fields and strengthening related basic work continuously.Energetic materials,including propellents,explosives pyrotechniques,and so on,are widely used in both industrial applications and at defense oriented establishments.However, there have been few reports on concerning mesoporous materials with energetic materials simultaneously.In this thesis,we focus on the connection and composition of these two materials in order to achieve the applications of mesoporous materials on energetic materials. The details of each chapter are list below:Chapter 2:Al-SBA-15 materials with cage-like macropores have been directly prepared by using micrometer-sized aluminium balls as a Al source,tetramethylorthosilicate(TEOS) as a silica source,and triblock copolymer Pluronic P123 as a template.The products (Al-SAB-15) have ordered two-dimensional(2-D) hexagonal mesotructure(space group of p6mm).The calcined Al-SBA-15 materials exhibit disordered macropores with the diameter of 70～80 nm and ordered mesopores with the diameter of 5 nm,a BET surface area of about 500 m²/g,Si/Al ratio of 20～80,and an integral ratio of tetrahedronal Al with octahedronal Al of about 2.Such unique properties give these materials potential for the applications,such as adsorption,catalysis and separation,etc.Chapter 3:Nanocomposites synthesized by self-assembly of organic compounds in nanometer-scale channels of ordered mesoporous silicas(SBA-15).The tendency of organic molecules to self-assemble when solvent evaporated at high temperature is described.The process is believed to be impossible in familiar low-boiling point solvent at room temperature. The complete impregnation of 4-nitrophenylhydrazine(NPH) can be achieved in N-methyl-2-pyrrolidone solvent at 100～105℃,which optimizes the interactions of the organic molecules-matrix of mesoporous silica SBA-15 and accommodates maximum amount of NPH around 60 wt%,suggesting that the loading of NPH depends on the mesopore volume of the matrix.Hydrogen bonds are considered as the inducement for organic molecules self-assembly.DSC thermal analysis show that the exothermic temperature of the nanocomposites is about 180℃compared with 158℃of pure NPH.Chapter 4:A new method of ammonium perchlorate(AP) oxidation has been developed to remove organic templates of mesoporous materials at relatively low temperature(80～120℃).Periodic mesoporous organosilicas(PMOs) with ethane-bridged prepared by using triblock copolymers P123 as a template are chosen as an example to demonstrate the AP treatment method.The resultant template-free PMO-80 products at 80℃have a larger pore size(7.2 nm) and volume(1.40 cm³/g) compared to solvent-extracted sample(6.9 nm and 1.06 cm³/g).No framework shrinkage is observed based on XRD results.TEM images show that the PMO-80 sample has a highly ordered mesostructure.This template removal strategy can be extended to prepare other nanoporous materials like pure mesoporous silicas.Chapter 5:The Co₃O₄ nanoparticles supported by silicas with different mesostructures were synthesized and characterized.Their catalytic performance for the decomposition of ammonium perchlorate was investigated by DSC and TG.The results indicated that the confined nano-sized Co₃O₄ made the temperature of the lower-temperature exothermic peak of ammonium perchlorate disappear,the temperature of the higher-temperature exothermic peak of ammonium perchlorate decrease by about 150℃and the apparent decomposition heat increase from 392 to above 1400 J/g.The Co₃O₄ supported by SBA-15 showed best catalytic performance for the thermal decomposition of ammonium perchlorate than other catalytic systems.