Hydrophobic silica composite aerogels using poly(methyl methacrylate) by rapid supercritical extraction process

• Published in: Journal of sol-gel science and technology Vol. 83; no. 3; pp. 692 - 697
• Main Authors: Jung, Hae-Noo-Ree, Lee, Yoon Kwang, Parale, V. G., Cho, Hyung Hee, Mahadik, D. B., Park, Hyung-Ho
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-09-2017; Springer Nature B.V
• Subjects: Aerogels; Ceramics; Chemical industry; Chemistry and Materials Science; Composites; Contact angle; Differential thermal analysis; Differential thermogravimetric analysis; Extraction; Glass; Heat transfer; Hydrophobicity; Inorganic Chemistry; Materials Science; Nanotechnology; Natural Materials; Optical and Electronic Materials; Original Paper: Sol-gel and hybrid materials with surface modification for applications; Polymethyl methacrylate; Silicon dioxide; Tetraethyl orthosilicate; Thermal analysis; Thermal conductivity; Thermal decomposition; Silica composite aerogel; Poly(methyl methacrylate); Transparency; Thermal decomposition; Hydrophobic
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-017-4438-4

A poly(methyl methacrylate) solution was mixed in an optimized tetraethoxysilane-based silica sol and a silica aerogel was obtained by a rapid supercritical extraction process. The hydrophobicity was enhanced by an addition of poly(methyl methacrylate), the silica aerogel prepared with 6 wt% poly(methyl methacrylate) has the contact angle of 156° with low density (0.067 g/cm
3
), high surface area (829 m
2
/g), and low thermal conductivity (0.072 W/m·K). The thermogravimetric-differential thermal analysis also showed that the aerogels were hydrophobic up to a temperature of 393 °C. An extra hydrophobicity could be expected for silica aerogel using poly(methyl methacrylate) through the surface modification of silica aerogel with generated –OCH
3
and –CH
3
radicals by the thermal decomposition of poly(methyl methacrylate) excluding poly(methyl methacrylate) itself. This study provided a simple and cost effective method that used an inexpensive polymer additive without using an expensive surface modification agent nor hydrophobic silica precursor.
Graphical Abstract