Pickering Emulsion Stabilized by Microporous Organic Polymer Particles for the Fabrication of a Hierarchically Porous Monolith

A hierarchically porous monolith comprising the melamine-based microporous organic polymer (MOP) particles was prepared by the Pickering emulsion templating method. The MOP particles were synthesized by polycondensation of melamine and terephthaldicarboxaldehyde. Because of the balanced presence of hydrophilic nitrogen containing groups and hydrophobic benzene rings, the MOP particles showed good amphiphilicity. A Pickering emulsion was prepared, where cyclohexane droplets with an average size of about 25 μm were stabilized by the MOP particles (3.4 wt %) in an aqueous continuous phase. The cyclohexane internal phase fraction was slightly higher than 60%. The emulsion showed no phase separation even after two weeks. The Pickering emulsion containing a small amount of polyvinyl alcohol (1 wt %) in a continuous phase as a reinforcement was used as a template for the fabrication of a monolith of the MOP particles. The Pickering emulsion was freeze-dried to produce a hierarchically porous monolith. The MOP mo...