Highly permeable macroporous polymers via controlled agitation of emulsion templates

Abstract

This work presents an investigation into how the pore diameter, pore throat diameter and permeability of emulsion templated macroporous polymers (polyM/HIPE) can be controlled by the energy input to the original surfactant stabilized medium/high internal phase emulsion (M/HIPE) template. Templates with internal phase volumes of 60%, 70% and 80% were examined. It was found that the equations used for predicting droplet size in emulsions are also suitable for predicting pore size in emulsion templated macroporous polymers. Pores were found to be larger for macroporous polymers produced from emulsions with lower internal phase volume ratios for the same energy input to the emulsion template. The relative size of pore throats compared to that of the pores was found to increase with decreasing mean pore size especially those produced from emulsions with 80% internal phase volumes. Gas permeability was found to increase linearly with pore throat diameter of polymers with similar porosity but decreases with decreasing porosity. However it was possible to produce highly permeable macroporous polymers by polymerisation of MIPEs with an internal phase percentage of 60% if the energy input during emulsification was minimal as this resulted in larger droplets leading to larger pore and pore throat sizes in the polyMIPE. However high levels of coalescence in the template emulsion prior to polymerisation were seen to drastically decrease the permeability of the resulting macroporous polymers.