Hybrid silica aerogels modified with polyethylene glycol (PEG) were successfully fabricated on the large window glass by an ambient drying process after solvent exchange and surface modification. Surface cracking was effectively prevented by adding PEG, which acted as a drying control chemical additive. The particle size of silica aerogel increased with the addition of PEG, while the pore size and volume decreased. The thermal conductivity and transmittance increased and decreased with further PEG modification more than 20 wt%, respectively, which is detrimental to aerogel applications. Although physical properties of silica aerogels were found to be good regardless of PEG content, tailored properties such as thermal conductivity and transmittance were observed for the aerogels with 10 wt% PEG. Modified hybrid surfaces of the silica/PEG aerogels were hydrophobic, exhibiting specific surface area of ~1028 m2 /g, total pore volume of ~1.2 cm3 /g, average pore diameter of ~5.5 nm, penetration ratio of ~70%, and thermal conductivity of ~0.02 W/mK.

Keywords: Silica aerogel, Polyethylene glycol (PEG), Sol-gel, Ambient drying, Drying control chemical additive (DCCA), Hybridization.