Release Behavior of Polymeric Vesicles in Solution Controlled by External Electrostatic Field.

We found that the polymeric vesicles from the self-assembly of amphiphilic block copolymer polystyrene--poly(acrylic acid) (PS--PAA) in the dioxane/water mixture can be deformed, broken and finally divided into smaller ones via the external electrostatic field. The higher the electrostatic field intensity, the smaller the vesicles. More importantly, this fission phenomenon induced by electrostatic field can be used to control the release behavior of the vesicles. Our experimental results show that the Nile Red (NR) molecules encapsulated inside the cavity of vesicles can be accurately released by controlling the electrostatic field intensity and the release time. These findings not only enrich the knowledge for the external field induced transformation of polymer structures, but also provide a new and highly convenient approach for the controllable release of polymersomes in solution.