Preparation of water-in-oil emulsions using a hydrophobic polymer membrane with 3D bicontinuous skeleton structure

Epoxy-based polymer (EP) membrane with 3D bicontinuous skeleton structure was firstly processed into tubular membrane and used in membrane emulsification for water-in-oil (W/O) microspheres. Since uniform W/O microspheres have not been obtained using shirasu porous glass (SPG) membrane unless SPG membrane was rendered hydrophobic by treatment with silanes, it is desired to find a hydrophobic polymer membrane which is capable of providing uniform W/O microspheres. To testify the feasibility of EP membrane in membrane emulsification, uniform agarose (coefficient variation (CV)=11.8%) and Ca-alginate (CV=11.4%) microspheres were achieved with EP membrane by direct and premix membrane emulsification, respectively. In comparison with SPG membrane, EP membrane showed good performance in whether direct or premix membrane emulsification in terms of the droplets size distribution and stability of membranes due to its narrow pore size distribution and uniform hydrophobic surface. SPG membrane is chemically unstable and dissolves under basic aqueous condition. However, it was found that EP membrane could tolerate 1 M NaOH aqueous solution for at least one week and keep its stable hydrophobic surface. Hence, EP membrane could be used in alkali condition, which enables to extend the range of applications in membrane emulsification. So EP membrane had huge potential in further preparation of W/O emulsions.