Polymerization and carbonization of high internal phase emulsions

High internal phase emulsions (HIPEs) of styrene and divinylbenzene (DVB), with 0-40% vinylbenzyl chloride (VBC) in the oil phase, were polymerized to give porous polymers (pore volumes 84-92%), which were sulfonated and carbonized at temperatures up to 700°C to obtain macroporous carbon monoliths. On carbonization, overall sample dimensions decreased, whilst percentage pore volume, compressive strength and compressive modulus increased. Scanning electron microscopy (SEM) showed typical HIPE-derived structures of cages (several μm across), interconnected by smaller windows, for polymer and carbon samples. Distributions of cage and window size were evaluated from electron micrographs. Average cage and window sizes decreased on carbonization approximately in proportion to the reduction in overall sample dimensions, and also decreased with increasing VBC content in the HIPE. Mercury intrusion porosimetry gave distributions of pore size in reasonable agreement with area-distributions of window size determined from SEM images. © 2004 Society of Chemical Industry.