NEW ORGANIC AEROGELS BASED UPON A PHENOLIC-FURFURAL REACTION

The aqueous polycondensation of (1) resorcinol with formaldehyde and (2) melamine with formaldehyde are two proven synthetic routes for the formation of organic aerogels. A new type of organic aerogel based upon a phenolic-furfural (PF) reaction was recently discovered. This sol-gel polymerization has a major advantage over past approaches since it can be conducted in alcohol (e.g., 1-propanol), thereby eliminating the need for a solvent exchange step prior to supercritical drying from carbon dioxide. The resultant aerogels are dark brown in color and can be converted to a carbonized version upon pyrolysis in an inert atmosphere. Brunauer-Emmett-Teller (BET) surface areas of 350-600 m(2)/g have been measured, and transmission electron microscopy reveals an interconnected structure of irregularly shaped particles or platelets with similar to 10 nm dimensions. Thermal conductivities as low as 0.015 W/m K have been recorded for PF aerogels under ambient conditions. Chemistry and structure-properly relationships of these new materials are described.