Well-Defined Amphiphilic Poly(2-oxazoline) ABA-Triblock Copolymers and Their Aggregation Behavior in Aqueous Solution

Self‐organization of block copolymers in solution is a way to obtain advanced functional superstructures. The synthesis of well‐defined polymethyloxazoline‐block‐polyphenyloxazoline‐block‐polymethyloxazoline triblock copolymers is described and proven by 1H NMR spectroscopy, SEC, and ESI–MS. The surprisingly water‐ soluble block copolymers do self‐organize in aqueous solutions uniquely forming three coexisting well‐defined structures: unimolecular micelles, micellar aggregates, and very form‐stable polymersomes. This is the first example of a polymersome forming ABA‐triblock copolymer with a glassy middle block. The spherical vesicles are analysed by scanning electron microscopy and transmission electron microscopy. It could be shown that these vesicles are indeed hollow spheres. Here, it is demonstrated that water‐ soluble ABA‐ triblock copolymers based on poly(2‐oxazolines) are capable of forming form‐stable polymersomes in aqueous solution without using nano precipitation techniques. These structures coexist with micellar and unimicellar motives as shown with dynamic light scattering and electron microscopy.