Emulsion-derived hierarchically porous polystyrene solid foam for oil removal from aqueous environment

Herein, a high internal phase emulsion (HIPE) technique to fabricate hierarchically porous monolithic Fe3O4/polystyrene composite material has been described. A novel co-stabilizer system of Span 20 and Fe3O4 solid particles was adopted to prepare the styrene-based emulsion. By adjusting the surfactant level, the concentration of Fe3O4 particles, and water content, a hierarchically interconnected porous material with a secondary pore structure of nano/micro size was constructed. In addition, the resulting composite polymer material exhibited excellent thermal stability, attributing to the good dispersion of Fe3O4 particles in the polymer matrix and strong bonding between solid particles and polymer chains. Moreover, the oil adsorption capacity of the solid foam was 16 times its own mass even after 10 cycles of oil/water separation. Importantly, the polystyrene solid foam exhibited hydrophobicity and oleophilicity without any further modification. Moreover, the incorporation of Fe3O4 particles allowed the composite material to be conveniently collected under an external magnetic field. All these features together make the polystyrene composite material an ideal adsorbent in the oil/water separation.