UV-visible light: A novel route to tune the type of an emulsion

The light-induced control of the type (oil or water continuous medium) of e mulsions stabilized by an appropriate combination of two polyelectrolyte su rfactants is described in this paper. Due to its balanced hydrophilic-lipop hilic properties, the first polymeric emulsifier (denoted BHL) has the abil ity to stabilize both direct and inverse emulsions and play the role of the main emulsifier of the n-dodecane-water system. The second one is a photor esponsive amphiphilic polymer (PR polymer) used at such low concentrations that the sole presence of the PR polymer as an emulsifier leads to the form ation of unstable emulsions. The chromophore groups randomly distributed al ong the PR polymer backbone enable the adjustment of its HL properties upon irradiation by near-UV light. We demonstrate that the change in hydrophobi city of the PR polymer induced by irradiation can be suitably used to tune the type of the liquid-liquid dispersion containing both polymers. Conseque ntly, UV-visible light is presented as a novel trigger to control the emuls ion type.