Emulsion-templated porous carbon monoliths derived from tannins

Tannin-based, carbonised, polymerised High Internal Phase Emulsions (polyHIPEs) are described in detail for the first time. Such highly porous materials were prepared by emulsion-templating, using an aqueous phase made of tannin and a low amount of hexamine dissolved in water, sunflower oil, and ethoxylated castor oil. After hardening of the tannin-based resin, the oil was leached out and the resultant monoliths were pyrolysed. The porous structure of carbon polyHIPEs prepared with an initial oil fraction ranging from 43 to 80 vol.% has been investigated, as well as their mechanical and thermal properties. We show that the most homogeneous materials, having the smallest pores, the narrowest pore size distributions and also the highest mechanical properties, are those made with an initial oil fraction around 70 vol.%. Such value is close to random and hexagonal close packing fractions: 64% and 74%, respectively.