Micellar Structures of Hydrophilic/Lipophilic and Hydrophilic/Fluorophilic Poly(2‐oxazoline) Diblock Copolymers in Water

Abstract

Amphiphilic poly(2‐alkyl‐2‐oxazoline) diblock copolymers of 2‐methyl‐2‐oxazoline (MOx) building the hydrophilic block and either 2‐nonyl‐2‐oxazoline (NOx) for the hydrophobic or 2‐(1H,1H′,2H,2H′‐perfluorohexyl)‐2‐oxazoline (FOx) for the fluorophilic block were synthesized by sequential living cationic polymerization. The polymer amphiphiles form core/shell micelles in aqueous solution as evidenced using small‐angle neutron scattering (SANS). Whereas the diblock copolymer micelles with a hydrophobic NOxn block are spherical, the micelles with the fluorophilic FOxn are slightly elongated, as observed by SANS and TEM. In water, the micelles with fluorophilic and lipophilic cores do not mix, but coexist.

Poly(2‐oxazoline)s based on fatty acids

“…When the location of the tracer was changed from being attached to the hydrophobic or hydrophilic block, similar results were obtained [55]. It was demonstrated by small angle neutron scattering that the poly(MeOx-b-NonOx) copolymers self-assemble into spherical core-shell micelles with the core consisting of stretched poly(NonOx) blocks and the corona consisting of coiled poly(MeOx) blocks [56,57]. The micellization of poly(EtOx-b-NonOx) in biphasic waterionic liquid mixtures was studied by Schubert and coworkers [58].…”

Design Strategies for Functionalized Poly(2-oxazoline)s and Derived Materials

“…Depending on the relative content of the p n NonOx blocks, the size and the morphology of the surface micelles could be varied. Jordan, Papadakis and co-workers investigated the micellar structures of amphiphilic diblock copolymers synthesized by sequential CROP of MeOx as hydrophilic and either n NonOx as hydrophobic or (9F) n HxOx as fluorophilic part [172]. The copoly(2-oxazoline)s formed core/shell micelles in aqueous media.…”

“…Structural formula of bipyridine-functionalized poly(2-oxazoline)s that can be used as macroligands in atom-transfer radical polymerizations (bottom; for details, see reference [172]). …”

Bioinspired Poly(2-oxazoline)s

“…Amphiphilic block copoly(2-oxazoline)s with a poly(2-perfluoroalkyl-2-oxazoline) hydrophobic block were demonstrated by Nuyken to aggregate into micellar structures in aqueous solution [80]. To circumvent the very low nucleophilicity of perfluoralkyl oxazoline monomers that decelerate the polymerization, Jordan and Papadakis et al reported the polymerization of 2-fluoroalkylethyl-2-oxazoline monomers where the strong electron withdrawing perfluoroalkyl chain is decoupled from the 2-oxazoline ring [81]. Amphiphilic block copolymers of MeOx with fluorinated monomers were prepared, which self-assembled into micelles with an elongated core-shell structure, presumably due to the high stiffness of the perfluorinated chain and the strong segregation from the water phase.…”