Systematic tuning of pore morphologies and pore volumes in macroporous materials by freezing

Abstract

Freezing and its combination with emulsion-templating are investigated to systematically tune pore morphologies and volumes in macroporous materials. Macroporous structures with controllable pore morphologies are formed under defined freezing conditions. Oil-in-water emulsions are processed to produce porous polymeric materials with a controlled proportion of ice-templated pores and emulsion-templated pores by systematically changing the volume ratio of the internal oil droplet phase to aqueous continuous phase in the emulsions. Pore morphology, bulk density, and pore volumes of these macroporous materials can thus be systematically tuned. Chemical crosslinking and sol–gel processing are further employed to produce porous polymeric and inorganic materials (silica, silica–alumina, and zirconia) with enhanced mechanical stability and hierarchical porosity.