Surface Modification and Reinforcement of Silica Aerogels Using Polyhedral Oligomeric Silsesquioxanes

• Published in: Langmuir Vol. 28; no. 43; pp. 15362 - 15371
• Main Authors: Duan, Yannan, Jana, Sadhan C, Reinsel, Anna M, Lama, Bimala, Espe, Matthew P
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 30.10.2012
• Subjects: Chemistry; Colloidal state and disperse state; Exact sciences and technology; General and physical chemistry; Porous materials; Modification; Binary compound; Silsesquioxane polymer; Aerogel; Durability; NMR spectrometry; Porous material; Density; Silica; Solid state; Absorption; Fractal dimension; Polarity; Surface area; Silane
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la302945b

This study evaluated polyhedral oligomeric silsesquioxane (POSS) molecules as useful, multifunctional reinforcing agents of silica aerogels. Silica aerogels have low-density and high surface area, although their durability is often compromised by the inherent fragility and strong moisture absorption behavior of the silica networks. POSS molecules carrying phenyl, iso-butyl, and cyclohexyl organic side groups, and several Si–OH functionalities were incorporated into silica networks via reactions between Si–OH functionalities in POSS molecules and silanes. Solid state 13C and 29Si NMR spectra established that greater than 90% of POSS molecules grafted onto silica networks and led to an increase in fractal dimensions. An almost 6-fold increase in compressive modulus was achieved with less than 5 wt % trisilanol phenyl POSS, and a 50-fold decrease in polarity with negligible changes in density were seen in aerogels modified with less than 5 wt % trisilanol isobutyl POSS.