Self-Assembling Amphiphilic Hyperbranched Polyglycerol-Polystyrene Copolymers for Encapsulation

Phospholipids, dendrimers, and polymers are each able to assemble to form vesicles, but each has limitations such as leakiness and multistep syntheses. A new class of versatile amphiphilic block copolymers is reported containing hyperbranched polyglycerol (HPG) and polystyrene (PS) units. These compounds self-assemble into polymersomes (HPGsomes). Under solvent exchange methods, amphiphilic polystyrene-HPG diblock (PS-b-HPG) structures are self-assembled and characterized by transmission electron microscopy. The assemblies are robust up to 95 °C in polar, protic solvents, and encapsulate dyes with minimal release. Polymersomes are typically assembled from linear amphiphilic polymers; however, it is shown that combining linear and hyperbranched polymers is a feasible strategy to encapsulation. Amphiphilic block copolymers prepared by clicking polystyrene azide to alkyne-initiated hyperbranched polyglycerol (HPG) self-assemble into stable vesicles called "HPGsomes." These HPGsome encapsulate dyes and are quite stable.