Carbon meringues derived from flavonoid tannins

New macro-cellular carbons, called carbon meringues, have been prepared by whipping until stiff an aqueous solution of tannin until liquid foam was obtained, which was next stabilized in an oven and pyrolysed, hence their name. With such cheap, fast and very easy process, flawless, homogeneous carbon foams were obtained in a wider range of density than that of more conventional cellular vitreous carbon (CVC) foams derived from similar formulations but made by physical foaming. The porosity, the average cell size and the cell wall thickness were only controlled by the initial concentration of tannin, all other things being equal. The resultant carbon meringues were fully investigated by electron microscopy, X-ray tomography, mercury porosimetry, Kr and N2 adsorption, thermal conductivity and mechanical compression studies. Differences with former CVC foams, and advantages of the new process and materials have been emphasised.