Reversible light-induced critical separation

A reversible, critical phase separation induced by UV light at 350 nm has been achieved by doping a small amount of photosensitive surfactant into an AOT-stabilised water-in-decane microemulsion. The initial and separated phases were analysed by small-angle neutron scattering (SANS), which suggests irradiation produces two coexisting water-in-oil microemulsions with relative droplet concentrations of 1 : 3. To better understand the effect of the photosurfactant, drop shape analysis tensiometry was used, showing a change in the effectiveness of the interfacial film under different irradiation conditions.