The BET specific surface area (SSABET) of all SHCPs was >530 m 2 •g -1 (Table ), with SHCP-1 displaying the lowest SSABET of 539 m 2 •g -1 . A trend can be seen across the catalyst set, with SSABET increasing dramatically to a maximum of 1059 m 2 •g -1 in SHCP-3 before gradually decreasing to 688 m 2 •g -1 in SHCP-10. A clear trade-off between porous properties and sulfonation density was observed. In SHCP-1 and SHCP-2, inefficient hypercrosslinking occurs due to the relatively low catalyst to monomer molar ratios, as evidenced by C-Cl in ssNMR and the presence of higher concentrations of residual Cl in XPS (Table ). Although SHCP-3 displays the highest SSABET of the set, some evidence of remaining C-Cl was again seen during characterisation. It is likely that the degree of sulfonation is insufficient to become significantly detrimental to the porous properties. In previous examples, the self-condensation of 4,4'bis(chloromethyl)biphenyl catalysed using triflic acid yielded HCPs with SSABET of up to 1842 m 2 •g -1 , much higher than the approach herein. However, the production of SHCP-3 requires just one third the amount of acid catalyst used therein. When further increasing the chlorosulfonic acid concentration, as in SHCP-4 to SHCP-10, the resulting SSABET worsen due to the increased sulfonation. Even with the trade-off between SSABET and acidity, these materials have excellent porous properties considering their high sulfonation density. The carbazole-based SHCP with a comparable SO3H concentration of 3.7 mmol•g -1 displayed a SSABET of just 346 m 2 •g -1 . Table . Summary of SO3H content and textural properties of SHCPs produced from various ratios of catalyst to monomer, including BET specific surface area, SSABET, volume of micropores, VMICRO, and total pore volume, VTOT.