상압건조 나노다공성 실리카 에어로젤에 대한 용매의 영향

Abstract

Nano porous, transparent silica aerogels monoliths were prepared under ambient drying (1 atm, 270oC) condition byhexane, n-heptane and xylene, were selected in the point view of low surface tension and vapor pressure in order to restraina formation of cracks during drying. Crack-free silica aerogels with over 93 % of porosity and below 0.14 g/cm3 of densitywere obtained by solvent exchange and surface modification under atmosphere condition. Optimum solvent was confirmedn-heptane among these solvents through estimation of FT-IR, TGA, BET and SEM. Modified silica aerogel exhibited ahigher porosity and pore size compare to unmodified aerogels. Hydrophobicity was also controled by C-H and H-OHbonding state in the gel structure and heat treatment over 400oC effects to the hydrophobicity due to oxidation of C-Hradicals.