Monolithic Cellular Graphitic Carbon from Romp-Derived Polydicyclopentadiene Aerogels

Porous carbons and carbon aerogels are useful as electrodes for batteries and fuel cells, catalyst supports and separation/filtration media. Monolithic carbon aerogels are usually obtained by pyrolysis at up to 1100 ⁰ C of organic (polymeric) aerogels, mainly based on resorcinol-formaldehyde resin. Other organic aerogels that have been converted to porous carbons include polyacrylonitrile, polyimide, polyurea and polybenzoxazine. Here, we demonstrate the preparation of carbonizable aerogels based on polydicyclopentadiene (pDCPD) synthesized via ring opening metathesis polymerization (ROMP) of the monomer using a second-generation Grubbs' catalyst. Since pDCPD is not substantially crosslinked, the resulting aerogel monoliths are deformed severely relative to the shape of their molds. That issue was resolved by post-gelation grafting of the pDCPD wet-gels with polymethylmethacrylate (PMMA) using AIBN-induced free-radical chemistry. The resulting aerogel monoliths are uniform and robust. Pyrolysis of those aerogels at 800 ⁰ C under Ar yields electrically conducting amorphous carbons (yield: 30% w/w), which in turn were graphitized at 2300 ⁰ C to yield (93% w/w) highly conducting monolithic cellular (~3 micron diameter) graphitic carbon.