Hierarchical Assembly of Star Polymer Polymersomes into Responsive Multicompartmental Microcapsules

We report a novel approach to realizing programmable encapsulation and following release of different compounds in a sequential way from multicompartmental microcapsules assembled from preformed polymersomes. The polymersomes, or polymeric vesicles, are formed through electrostatic interactions between a cationic miktoarm star polymer, namely poly(ethylene oxide)(113)-(quaternized poly(2-(dimethylamino)ethyl methacrylate)(60))(4), and a linear anionic polyelectrolyte, (poly(styrenesulfonate)(20)), and then used as the main component to fabricate microcapsules with tannic acid via hydrogen-bonded layer-by-layer assembly. The hydrogen bonding between tannic acid and polymersomes is sensitive to external pH, and the structure of the polymersomes strongly depends on the ionic strength of the surrounding media. This combination facilitates dual-responsive behavior of these multicompartmental polymersome-based microcapsules with the programmable release of two different types of encapsulated molecules (anionic and cationic molecules) from core and shell regions of the microcapsules independently. The integration of responsive nanocarriers into functional microcapsules provides a new way to fabricate multiresponsive hierarchical microstructures with programmed sequential release of different molecules.