Multicompartment micelles based on hierarchical co-assembly of PCL-b-PEG and PCL-b-P4VP diblock copolymers

Multicompartment micelles are prepared via the hierarchical co-assembly of two diblock copolymers, poly(e-caprolactone)-b-poly(ethylene glycol) (PCL-b-PEG) and poly(e-caprolactone)-b-poly(4-vinylpyridine) (PCL-b-P4VP) in aqueous solution. These two polymers first assemble into mixed shell micelles through hydrophobic interaction among PCL chains. PCL chains form the micellar core, while PEG and P4VP chains form the micellar shell. Regulating the pH value above the pKa of P4VP can induce hydrophobic phase-segregated P4VP patches forming on the surface of mixed shell micelles. When hydrophilic PEG chains cannot stabilize theses micelles with hydrophobic patches, they will furthermore assemble as the subunits into MMs with different morphologies. These MMs can be revealed by transmission electron microscopy through P4VP chains positive staining.