Resorcinol-formaldehyde and carbon aerogel microspheres

Aerogels are a unique class of materials possessing an open-cell structure with ultrafine cells/pores (<100 nm), high surface area (400-1100 m(2)/g), and a solid matrix composed of interconnected particles, fibers, or platelets with characteristic dimensions of 10 nm. Although monolithic aerogels are ideal candidates for many applications (e.g. transparent window insulation), current processing methods have limited their introduction into the commercial marketplace. Our research focuses on the formation of resorcinol-formaldehyde (RF) aerogel microspheres which offer an attractive alternative to monolith production. An inverse emulsion polymerization is used to produce these spherical gel particles which undergo solvent exchange followed by supercritical drying with carbon dioxide. This process yields aerogel microspheres (10-80 mu diameter) which can be used as loosely packed powders, compression molded into near-net shapes using a polymer binder, or used as additives in conventional foaming operations to produce new aerogel composites with superior thermal properties. The emulsification procedure, thermal characterization, mechanical properties, and potential applications of RF aerogel microspheres will be discussed.