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Abstract

A hierarchically porous carbon monolith with a density of 0.059 g cm?3 (97 % porosity) was generated through the carbonization of an emulsion-templated monolith formed from a deep-eutectic polymer based on the polycondensation of 2,5-dihydroxy-1,4-benzoquinone with excess urea. The mechanical integrity and thermal stability of the monolith were successfully enhanced through a chain extension reaction with terephthaloyl chloride (TCL) that occurred during/following the formation of a high internal phase emulsion (HIPE). The bimodal, open-cell macroporous structure of the monolith consisted of many smaller voids with an average diameter of 15 [small micro]m and some larger voids with an average diameter of 49 [small micro]m. Carbonization of the monolith introduced microporosity and meso/macro-porosity, yielding a high specific surface area (812 m2 g?1, largely from micropores), a micropore volume of 0.266 cm3 g?1 (an average diameter of 0.67 nm), and a meso/macro-pore volume of 0.238 cm3 g?1 (an average diameter of 8.1 nm). The elemental composition of the chain-extended polymeric monolith was similar to that predicted from the HIPE components except for a relatively low nitrogen content which may indicate the loss of some urea groups during the chain extension reaction with TCL. The nitrogen-carbon bonds in the carbon monolith from the chain-extended polymer were around 47% pyridinic, 20% pyrrolic, and 33% graphitic. While chain-extension reduced the nitrogen content, the mechanical integrity and thermal stability were enhanced, which was key to generating a highly microporous carbon monolith with a hierarchical porous structure. The carbon monolith exhibited promising results for aqueous solution sorption applications, in both batch and flow modes, owing to its advantageous combination of properties.