Carbon nanotube-based aerogels as preformed porous fibrous network for reinforcing lightweight composites

Abstract

Lightweight composites achieved by the incorporation of voids or pores are limited by their notoriously poor mechanical properties. Reinforcement of these composites by the incorporation of high aspect ratio nanofibers/tubes is challenging due to the difficulty and expense of efficiently dispersing the reinforcing elements in the desired matrix. Here, we present a method to fabricate preformed, porous fiber networks that can be infiltrated by the matrix of choice. First, we demonstrate the synthesis of mechanically robust, electrically conductive low-density carbon nanotube-based aerogels with macroscopic dimensions. The nanotube aerogels are prepared by the sol-gel polymerization of resorcinol with formaldehyde in an aqueous suspension containing a dispersion of highly purified single-walled carbon nanotubes. Subsequent drying and pyrolysis result in freestanding monoliths consisting of a random network of carbon nanotube bundles decorated and cross-linked by graphitic carbon nanoparticles. Such nanotubebased aerogels exhibit electrical conductivities improved by an order of magnitude compared to those of foams without nanotubes and elastic behavior up to compressive strains as large as ~80%. Finally, we show how these aerogels can be infiltrated by a wide range of matrix materials to form lightweight composites with enhanced mechanical and electrical properties.