Tuning the morphology of triblock terpoly(2-oxazoline)s containing a 2-phenyl-2-oxazoline block with varying fluorine content

The formation of nanostructures in triblock terpolymers consisting of poly[2-ethyl-2-oxazoline-block-2-(1-ethylpentyl)-2-oxazoline-block-2-(Xfluorophenyl)-2-oxazoline] (X = di, tri, tetra and penta) was investigated in water. For this purpose a gradually increasing degree of fluorination was introduced in the molecular structures and its influence on the self-assembly was studied. It can be demonstrated that the basic form of aggregation of these systems resembles rod-like micelles, which tend, upon introduction of fluorinated blocks, to aggregate first into 2-dimensional and later into 3-dimensional super-aggregates. In the case of di- and pentafluorinated terpolymers well-defined structures were observed, which represent likely intermediate, stable transient structures formed during an assumed rod-to-vesicle transition. DLS and cryo-TEM were utilized to analyze the structural features of these nanostructures and a model for their further assembly into super-structures was developed.