Photostimulated Phase Separation Encapsulation

Polymer capsules were prepared by photostimulated precipitation of azobenzene-functionalized poly(styrene-alt-maleimide) copolymers dissolved in an oil phase and dispersed in a continuous aqueous phase. The oil phase is selected to be a near ϑ-solvent for the copolymers, such that the increasing polarity of the polymer due to the photochemical trans-to-cis isomerization induces polymer phase separation and migration to the interface. The resulting polymer walls are permanent even during storage in the dark or irradiation with visible light.