In-situ preparation and microstructure characterization of Hydrophobic Silica Aerogel

Based on the sol-gel method and acid-base two-step catalysis process,the hydrophobic silica aerogel with a high specific surface area is prepared by using tetraethyl orthosilicate(TEOS) as the precursors,N,N-dimethylformamide(DMF) as the drying control chemical additives and trimethylchlorosilane(TMCS) as the hydrophobic modification.The samples are tested and characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),Fourier transform infrared(FTIR) spectrometry,N2 physical adsorption and thermo gravimetric and differential thermal analyzer(TG-DTA).The results indicate that the prepared hydrophobic SiO2 aerogel is white powder with amorphous and continuous network porous structures.The pore size of SiO2 aerogel is distributed primarily in the narrow range of 35~40 nm,and the composition of the skeleton of SiO2 aerogel is an uniform spherical particle.The hydrophobic group(—CH3) linked on the surface of SiO2 aerogel is oxidized when heated from 304.08 to 430.45℃,and the aerogel became hydrophilic from hydrophobic.