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

• Published in: Polymer chemistry 2020-02, Vol.11 (6), p.1237-1248
• Main Authors: Daubian, Davy, Gaitzsch, Jens, Meier, Wolfgang
• Format: Article
• Language: English
• Subjects: Block copolymers; Chemical synthesis; Ethylene oxide; Glass transition temperature; Light scattering; Micelles; Nanoparticles; Polyethylene oxide; Polymer chemistry; Polymerization; Polyoxazolines; Room temperature; Self-assembly; Solvents; Temperature; Vesicles
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/c9py01559k

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 obtained via microwave-assisted polymerization of EHOx using a new nosylated PEO macroinitiator. The kinetics of the polymerization in different solvents was crucial to optimize the synthesis and revealed a controlled, yet fast polymerization of the AB diblock copolymer. Differential scanning calorimetry proved that PEO- b -PEHOx shows glass transition temperatures below room temperature, making it suitable for a wide range of self-assembly methods, especially under mild and solvent-free conditions. Self-assembly of PEO- b -PEHOx was then performed using film rehydration and solvent switch. In both cases, we were able to show the formation of various complex structures (multi-compartment micelles (MCMs), pseudo-vesicles and yolk/shell nanoparticles) by light scattering, TEM and Cryo-TEM. Our results show that PEO- b -PEHOx is a potent new AB diblock copolymer due to its fast synthesis and unique self-assembly behavior. A new PEO- b -PEHOx amphiphilic diblock copolymer was achieved which unlocked new complex self-assembled structures. Thanks to its hydrophobic oxazoline block with a long branched side chain, EHOx, various potent structures were obtained.