Synthesis and complex self-assembly of amphiphilic block copolymers with a branched hydrophobic poly(2-oxazoline) into multicompartment micelles, pseudo-vesicles and yolk/shell nanoparticles

We report on the synthesis and self-assembly of poly(ethylene oxide)-block-poly(2-(3-ethylheptyl)-2-oxazoline) (PEO-b-PEHOx), a new amphiphilic diblock copolymer obtainedviamicrowave-assistedpolymerization of EHOx using a new nosylated PEO macroinitiator. The kinetics of the polymerization indifferent solvents was crucial to optimize the synthesis and revealed a controlled, yet fast polymerizationof the AB diblock copolymer. Differential scanning calorimetry proved that PEO-b-PEHOx shows glasstransition temperatures below room temperature, making it suitable for a wide range of self-assemblymethods, especially under mild and solvent-free conditions. Self-assembly of PEO-b-PEHOx was thenperformed usingfilm rehydration and solvent switch. In both cases, we were able to show the formationof various complex structures (multi-compartment micelles (MCMs), pseudo-vesicles and yolk/shellnanoparticles) by light scattering, TEM and Cryo-TEM. Our results show that PEO-b-PEHOx is a potentnew AB diblock copolymer due to its fast synthesis and unique self-assembly behavior.