Hierarchically Arranged Pores in Macroporous Polymers Synthesized using High Internal Phase Emulsions Stabilized by Functionalized Titania Nanoparticles

摘要

High internal phase emulsions (HIPEs) are defined by a minimum droplet volume fraction of 74 vol-% (1). Water in oil (w/o) HIPEs consist of monomers and crosslinkers (2) as the organic phase and an electrolyte solution as the internal phase. These HIPEs are stabilized by surfactants such as Hypermer B246SF and can be polymerized to form conventional polyHIPEs. The emulsion structure at the gel point of polymerization becomes the pore structure of the resultant polyHIPE, thus the technique is termed emulsion templating. Typically, conventional polyHIPEs have pore sizes between 1 and 20 m (3) interconnected by pore throats, which are around 20% of the pore diameter (1). These foams are highly porous and interconnected, making them permeable to gases and wetting liquids (4). Small particles can also be used to effectively stabilize emulsions, forming particle-stabilized HIPE templates or Pickering-HIPEs, which can be polymerized using a radical initiator to give poly-Pickering-HIPEs (5). Poly-Pickering-HIPEs have larger closed-cell pores ranging from 200 to 700 m (6). We aim to combine the open and closed pore structures found in conventional and poly-Pickering-HIPEs respectively, to create a new class of hierarchical macroporous polymers.