Preparation And Modification Of Noval Organic Xerogel Microsphere

Aerogel is a novel type of porous materials with high specific surface area, high porosity, controllable pore size distribution and other superior properties. It can be wildly used in thermal insulation, adsorption, catalysis, energy storage and other fields. Organic aerogel is a major branch of the aerogel family.In comparison with the traditional block-shaped areogels, aerogel microspheres are easy to load in a container. The ambient pressure drying process is a necessary step for industrialization. By using hydrophobic modification we can largely reduce the shrinkage of aerogel during drying process and maintain its original properties. By doping metal into aerogel, we can get aerogels in different structures and properties. Our work is focus on these three aspects mentioned above. We use resorcinol and formaldehyde as precursors, Na2CO3 as catalyst and SPAN-80 as surfactant via reverse emulsion polymerization process to get organic aerogel microspheres. Then we use trimethylchlorosilane (TMCS) as modification agent to change the surface of the organic aerogels from hydrophilic to hydrophobic. We also prepared metal-doped organic aerogel hollow microspheres and hemispheres by doping metal salt into precursor through a reverse emulsion polymerization process. SEM, TEM, FT-IR and TG-DSC measurements were used to analyze the structure, morphology, and surface chemistry properties of these samples.The organic aerogel microspheres we prepared have a controllable size ranged from 50μm to 300nm. The factors that affect the morphology of these microspheres, such as stirring speed, surfactant concentration, precursor concentration and separation method were investigated. We find that after ambient pressure drying process, these aerogel microspheres with size ranged around several hundred nanometers can maintain their morphologies perfectly while microspheres with size ranged around several micrometers can not. It can be a new idea for ambient pressure drying process. The hydrophobic organic aerogels exhibit a much smaller shrinkage (15%) than the hydrophilic organic aerogels (50%) after ambient pressure drying. The smaller shrinkage represent the unique structure of aerogel has been preserved. This surface modification method will increase the value of ambient pressure drying process. The metal-doped organic aerogel hollow microspheres and hemispheres prepared have a controllable particle size ranged from 30μm to 1μm. The sample maintained its shape well after ambient pressure drying. We analyzed the factors that affect the morphology and structure of these hollow microspheres and hemispheres, such as stirring speed, metal salt concentration, metal salt type. The forming mechanism of these hollow microspheres and hemispheres was deduced. These aerogel materials with special morphologies and structures could be used in energy storage, adsorption, drug delivery and other fields.