Multicompartment Micelles by Aqueous Self-Assembly of μ-A(BC)_n Miktobrush Terpolymers

The aqueous self-assembly of μ-A(BC)_n miktobrush terpolymers has been studied using dynamic light scattering and cryogenic transmission electron microscopy. In this system, the A block is hydrophilic poly(ethylene oxide), O, the B block is hydrophobic poly(methylcaprolactone), "C", and the C block is hydrophobic and oleophobic poly(perfluoropropylene oxide), "F". Two terpolymers were examined: one with an average of about two C blocks and two F blocks and another with an average of about three C blocks and two F blocks. In both cases, the total molar mass is near 40 kg mol^-1, and the volume fraction of the single O block is greater than 50% of the whole. Both samples form multicompartment micelle structures with subdivided solvophobic cores of C and F domains. The morphologies observed are generally analogous to those previously observed for the self-assembly of μ-ABC miktoarm star terpolymers, namely, "raspberry" and "hamburger" micelles; however, an intriguing multicompartment polymersome morphology with compartmentalized solvophobic bilayers is also observed. These results are interpreted in terms of the relative strengths of the competing interactions among the three blocks and the solvent and in terms of the constraints imposed by the miktobrush architecture.