Chem. Mater. 2006, 18, 285-296
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Chemical, Physical, and Mechanical Characterization of Isocyanate Cross-linked Amine-Modified Silica Aerogels Atul Katti,† Nilesh Shimpi,† Samit Roy,*,† Hongbing Lu,*,† Eve F. Fabrizio,‡ Amala Dass,§ Lynn A. Capadona,| and Nicholas Leventis*,| School of Mechanical and Aerospace Engineering, Oklahoma State UniVersity, Stillwater, Oklahoma 74078, Ohio Aerospace Institute, 22800 Cedar Point Road, CleVeland, Ohio 44142, Department of Chemistry, UniVersity of MissourisRolla, Rolla, Missouri 65409, and Materials DiVision-Polymers Branch, NASA Glenn Research Center, 21000 Brookpark Road, M.S. 49-1, CleVeland, Ohio 44135 ReceiVed June 26, 2005. ReVised Manuscript ReceiVed October 24, 2005
We describe a new mechanically strong lightweight porous composite material obtained by encapsulating the skeletal framework of amine-modified silica aerogels with polyurea. The conformal polymer coating preserves the mesoporous structure of the underlying silica framework and the thermal conductivity remains low at 0.041 ( 0.001 W m-1 K-1. The potential of the new cross-linked silica aerogels for load-carrying applications was determined through characterization of their mechanical behavior under compression, three-point bending, and dynamic mechanical analysis (DMA). A primary glass transition temperature of 130 °C was identified through DMA. At room temperature, results indicate a hyperfoam behavior where in compression cross-linked aerogels are linearly elastic under small strains (
