Natural care products: deposition studies of sustainable polymers and surfactant mixtures

The aim is to reveal the properties of coacervate complexes of oppositely charged natural surfactants (medium-chain fatty acid salts) and biobased cationic polysaccharides deposited on surfaces. This is needed to develop formulated products with more sustainable ingredients. Neutron reflectometry measurements on polymer-surfactant mixtures upon dilution at various SLD contrasts are expected to provide detailed information on the layering of the components (polymers and surfactants) on the model surface, in terms of the position they occupy, the thickness of each layer, how layers interpenetrate each other and their density profile within the film along the distance from the surface. A pre-characterisation (visual inspection, DLS, SAXS and ellipsometry) has shown the formation of coacervates that deposit on a silica surface, occurring when the composition approaches the surfactant CMC.