Shedding the hydrophilic mantle of polymersomes

Block copolymers of polybutadiene-b-poly(ethylene glycol) were prepared in which both segments were coupled via an acid sensitive hydrazone moiety. Polymersomes that were subsequently formed showed a strong pH-dependent colloidal stability as a result of the pH sensitive removal of the PEG block. By mixing this stimulus responsive block polymer with an inert analogue it was possible to systematically remove percentages of PEG from the polymersome mantle. The minimum amount of surface PEGylation needed to retain stable polymersomes was found to be as low as five percent.