Ionic Liquid-Controlled Shape Transformation of Spherical to Nonspherical Polymersomes via Hierarchical Self-Assembly of a Diblock Copolymer.

Here, we report the self-assembly of poly(ethylene glycol) methyl ether-block-poly(ε-caprolactone) (PEG--PCL) copolymer in three ionic liquids (ILs) possessing different cations with common (trifluoromethylsulfonyl)imide anion. The observed polymeric nanostructures in ILs were directly visualized by room temperature conventional transmission and field emission scanning electron microscopy and were further examined for their size and shape by dynamic light scattering technique. The results show that through changes in the concentration of PEG--PCL and/or changing the solvent by using a different IL, we can effectively induce shape transformation of self-assembled PEG--PCL nanostructures in order to generate nonspherical polymersomes, such as worm-like aggregates, stomatocytes, nanotubes, large hexagonal and tubular-shaped polymersomes. These findings provide a promising platform for the design of biodegradable soft dynamic systems in the micro-/nano-motor field for cancer-targeted delivery, diagnosis and imaging-guided therapy, and controlled release of therapeutic drugs for treatment of many diseases. Non-spherical polymersome-based vaccines may be taken up more efficiently, especially against viruses for pulmonary drug delivery than the spherical polymersomes-based.