Membrane emulsification has been widely used in the manufacture of uniform soft and hard spherical particles. It is used to create uniform emulsion droplets whose sizes can be closely controlled. A disperse liquid phase is pressurised to permeate into the pores of a membrane, forming droplets in a drop-by-drop manner in a continuous phase on the other side of the membrane. The droplets formed are detached by applying well controlled detachment forces, which are result from the cross-flow of the continuous phase over the membrane surface, or the rotation of the membrane in the continuous phase. These two technologies are called cross-flow and rotating membrane emulsification, respectively. This paper presents examples of uniform complex spheres, sized from sub-micrometers to a few hundred micrometers, prepared using a pilot scale cross-flow membrane emulsification rig and a bentchtop rotating reactor. Emulsion stabilisation strategies vary from using small molecular surfactants, nanoparticles to surfactant free interfacial polymerisation. The examples demonstrate the advantages and versatility in formulation and manufacture of precisely size- and structure-controlled products using membranes.
- Membrane emulsification
- Uniform emulsion