Surfactant selection for accurate size control of microcapsules using membrane emulsification

Microencapsulation has long been developed for controlled delivery/release of active components in food, pharmaceutical, personal and home care, agrochemical and other functional products. Controlled release provides a means to increase the efficiency of active components by reducing the amount required in any given application. This approach also lowers contamination effects of active compounds in the application environment through the reduced dose. So far, numerous physical and chemical techniques have been developed to encapsulate liquids or solids. Among them emulsification has been widely used as a template stage to generate discrete spherical particulates with good control of the particle size. To facilitate good size and size distribution, emulsification methods have developed from conventional approaches such as turbulent shear mixing to a drop-by-drop production using membranes and/or micro-fluidics. However, the complexity of fluid systems can provide problems especially when larger droplets are desired and/or further processing is needed. We are currently exploring the combination of an advanced emulsification technique (cross-flow membrane emulsification) with the formulation of specific interface properties to achieve droplets with a desired larger size (20–50 μm) and narrow size distribution (from a very low viscous oil) that are suitable for use as templates in microcapsule manufacture.