Preparation And Characterization Of Organic Functional Transparent Mesoporous Silica Gel Monoliths

Large-sized, crack-free, transparent silica monoliths held peoples'attention and showed potential applications in the design of novel optical devices, such as lenses, chromophores, laser devices, and nonlinear optical media, because of their particular macro-morphology, favorable transparency, ordered mesoporous structure and large specific surface area. At present, many research groups devoted their lives on the research field of large-sized, crack-free,transparent silica monolithic mesoporous gels. It has been made great progress in the preparation of materials after years of researching. However, Large-sized, crack-free, transparent pure silica monoliths has the low degree of pore surface polarity and adjustable degeneration. Ensuring the integrity, transparency and orderliness of the internal structure of the materials, organic groups can be introduced into the transparent mesostructured silica monoliths. And by adjusting the loading and the group type of organic groups, we can precisely control of the size of the pore structure, pore surface polarity and improve the mechanical properties of materials for enriching the types and properties of solid substrate of organic dyes and expanding the application range in the reseach field of new optical device.Based on the problem, the control preparation of organic functional transparent mesoporous silica gel monolith in an acid system with non-ionic block copolymer surfactants template was systematically studied in this work. The organic functional transparent mesostructured silica gel monoliths were synthesized by using tetraethoxysiliane, Phenyltrimethoxysilane, triethoxy-methylsilane, trimethoxyvinylsilane,3-mercaptopropyltriethoxysilane, n-propyl-triethoxysilane,3-chloropropyltriethoxysilane as silica sources and using non-ionic surfactant P123, F127 and Brij56 as template respectively in the acid medium through fast sol-gel technique. The control preparation rules were studied detailedly at 60℃. The effect of various content of organic groups on the microstructure and macroscopic morphology of the materials in the synthesis and the gel drying process were characterized systematically. The major findings are as follows:(1) The Modification content of methyl groups can be adjusted in the 0-65% range while maintaining the integrity of transparent mesoporous gels. The pore size decreases while the content of methyl is increasing. The methyl hybridied transparent mesoporous silica monoliths with ordered hexagonal mesoporous structure were prepared by P123 as template. The pore size, pore volume and specific surface area of material can be adjusted at the range of 2.0-3.15nm,0.199-0.48cm3/g and 959.7-1058m2/g respectively. Moreover, the methyl hybridied transparent mesoporous silica gel monoliths with ordered Cubic mesoporous structure were prepared by F127 as template. The pore size, pore volume and specific surface area can be regulated at the range of 2.0-4.30nm,0.317-0.497cm3/g and 865.6-1046.4m2/g respectively. And the methyl hybridied transparent mesoporous silica monoliths with ordered mesoporous structure were prepared by Brij56 as template. The pore size, pore volume and specific surface area can be regulated at the range of 1.98-2.78nm, 0.242-0.48cm3/g and 974-1030.68m2/g.(2) Learn from the experience of methylation hybridization experiment, the type of silane coupling agent was extended. The vinyl, phenyl, mercaptopropyl, propyl, chloropropyl hybrided transparent and crack-free mesoporous silica gel monolithic material were successfully prepared by using P123 as a template, and the prepared materials all have ordered mesoporous phase. The pore size decreases and gelation time is prolonged while the content of organic groups is increasing. the results are as follows:a. The Modification content of vinyl groups can be adjusted in the 0-25% range while maintaining the integrity of transparent mesoporous gels. The pore size, pore volume and specific surface area of material can be adjusted at the range of 1.98-3.15nm,0.28-0.48cm3/g and 974-1042m2/g respectively.b. The Modification content of phenyl groups can be adjusted in the 0-25% range while maintaining the integrity of transparent mesoporous gels. The pore size, pore volume and specific surface area of material can be adjusted at the range of 2.56-3.15nm,0.324-0.48cm3/g and 819.19-984.72m2/g respectively. c. The Modification content of propyl groups can be adjusted in the 0-25% range while maintaining the integrity of transparent mesoporous gels. The pore size, pore volume and specific surface area of material can be adjusted at the range of 1.98-3.15nm,0.288-0.48cm3/g and 959.36-1042m2/g respectively.d. The Modification content of chloropropyl groups can be adjusted in the 0-25% range while maintaining the integrity of transparent mesoporous gels. The pore size, pore volume and specific surface area of material can be adjusted at the range of 2.0-3.15nm,0.129-0.48cm3/g and 959.7-1058m2/g respectively.e. The Modification content of mercaptopropyl groups can be adjusted in the 0-25% range while maintaining the integrity of transparent mesoporous gels. The pore size, pore volume and specific surface area of material can be adjusted at the range of 3.15-3.8nm,0.314-0.757cm3/g and 469.84-974m2/g respectively.The work that successfully prepareing the transparent monolithic silica gel hybrids with different organic groups, not only demonstrates that the original synthesis technology has a wide range of applicability, but also enrichs the skeleton components and surface properties of such materials. This is significant for the development of new optical devices.