Preparation And Properties Of Special Hybrid Aerogel

Aerogel is a kind of porous material with a three-dimensional network structure.Its unique properties such as low density and low thermal conductivity have attracted wide attention and its application fields are becoming increasing extensive.Polyhedral oligomeric silsesquioxanes(POSS)is a nano-sized caged silsesquioxane with a regular structure.It has excellent chemical and thermal stability and is usually used to modify polymers.In this work,silica xerogel and cellulose aerogel were prepared and modified with POSS.The effect of POSS on its physicochemical properties was studied.The following is the main research content:Firstly,POSS with different functional groups were synthesized,the methoxyl-terminated POSS(TDMS)and the ethoxyl-terminated POSS(TDES).The silica xerogel were prepared by TDMS and TEOS,and the effect of TDMS to xerogel mechanical properties,specific surface area,thermal conductivity and crystallization properties were studied.The specific surface area of silica xerogel cross-linked with TDMS increased to 936.24 m2/g.TDES can be used to hydrophobize xerogel,and the silica xerogel treated by TDES has excellent hydrophobicity.At the same time,the xerogel maintained good light transmission.Nanocrystalline cellulose(NCC)was prepared by sulfuric acid hydrolysis,at the same time,octa-amino POSS(OA-POSS)was synthesized.NCC aerogel was modified with OA-POSS and its density,microstructure,thermal stabilitys and the solvent absorption capacity was studied.It was found that OA-POSS can improve the solvent absorption capacity of the NCC aerogel.The nanofibrillated cellulose(NCF)was used to synthesize aerogel.At the same time,carboxyl terminated POSS(HDCS)was synthesized to modify the NCF aerogel and chemical vapor deposition(CVD)was used to hydrophobize NCF aerogel.By testing its BET,thermal conductivity,XRD,WCA,solvent absorption capacity,etc.,it was found that HDCS can improve the solvent absorption capacity of NCF aerogel,up to 140g/g,and the aerogel also has the favorable oil/water separation ability.