One Pot Synthesis of Multifunctional Aramid Aerogels

Aerogels are quasi-stable, low-density, three-dimensional assemblies of nanoparticles, but they are commonly associated with poor mechanical properties. The most successful efforts to improve their mechanical properties involve cross-linking of the skeletal nanoparticles with polymers. However, post gelation cross-linking is time-consuming. Hence, it is reasonable to seek robust all-polymer aerogels among polymers known for their high mechanical strength. As a result, here we report the facile one-pot synthesis of a new class of Kevlar-like aerogels based on the rather underutilized reaction of multifunctional isocyanates and carboxylic acids. The resulting materials are up to 84% v/v porous with surface areas as high as 380 m 2 g -1. The ultimate compressive strength per unit density is within 10% equal to that of Kevlar 49. The high specific energy absorption (37 J g -1) and Styrofoam-like thermal conductivity (0.028 W m -1 K -1) combined with thermal stability up to 350°C render aramid aerogels multifunctional materials suitable for defense, civil and transportation related applications. Upon pyrolysis at 800°C they can be converted to 80% (v/v) porous, electrically conducting carbons with surface areas as high as 474 m 2g -1. © 2012 Materials Research Society