title: Surface modification and reinforcement of silica aerogels using polyhedral oligomeric silsesquioxanes.
abstract: 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 (13)C and (29)Si 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.
authors.affiliation: Department of Polymer Engineering, The University of Akron, Akron, Ohio, 44325-0301 United States.
authors.forename: Yannan
authors.initials: Y
authors.lastname: Duan
authors.forename: Sadhan C
authors.initials: SC
authors.lastname: Jana
authors.forename: Anna M
authors.initials: AM
authors.lastname: Reinsel
authors.forename: Bimala
authors.initials: B
authors.lastname: Lama
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Espe