Self-Assembly of Poly(2-alkyl-2-oxazoline)s by Crystallization in Ethanol-Water Mixtures Below the Upper Critical Solution Temperature

Crystallization of poly(2-isobutyl-2-oxazoline) and poly(2-nonyl-2-oxazoline) is found to occur by room temperature annealing below the upper critical solution temperature in ethanol-water solvent mixtures. Both polymers produce similar self-assembled structures (see image), resembling the previously reported crystalline hierarchical structures obtained from hot aqueous poly(2-isopropyl-2-oxazoline) solutions above the lower critical solution temperature. These observations suggest that the crystallization induced self-assembly process is a rather general phenomenon occurring for semi-crystalline polymers in liquid-liquid two phase systems.