Manufacture of controlled emulsions and particulates using membrane emulsification

Crossflow and rotating membrane emulsification techniques were used for making oil-in-water (O/W) emulsions. The emulsions produced from a variety of oils and monomers (viscosity 7–528 mPas) exhibited narrow size distributions over a wide droplet size range, with the average droplet size ranging from less than 1 µm up to 500 µm. The monomer emulsions were further encapsulated to produce microcapsules through subsequent polymerisation reactions. The monodispersity feature of the primary emulsions was retained after the encapsulation. In comparison with other homogenisation methods, our experimental results demonstrated that the membrane emulsification technique is not only superior in emulsion droplet size controls, but also advantageous in energy efficiency and industrial-scale productions.

The XME experiments indicate that monodisperse monomer/oil in water emulsions can be readily formulated over a wide range of different process conditions. The monomer emulsion droplets obtained have been successfully polymerised into microcapsules while retaining the size characteristics in the primary emulsions. Although running the XME at significantly higher disperse fluxes can lead to droplet CVs exceeding the monodispersity threshold of 35%, the XME products would still make significantly favourite comparisons on size distribution characteristics with those produced from homogenisation. This makes the XME a highly attractive technology even for general emulsification appli- cations, given its other distinctive advantages such as simplicity, low energy consumption, easy scale-up and reproducibility prospects. Exploratory experiments on RMR show that highly uniform emulsion droplets can be produced, with the droplet size being dictated by the membrane rotational speed.