PEO-b-PCL-b-PMOXA Triblock Copolymers: From Synthesis to Microscale Polymersomes with Asymmetric Membrane

We report a new family of amphiphilic ABC triblock copolymers: poly(ethylene oxide)-block-polycaprolactone-block-poly(2-methy1-2-oxazoline) (PEO-b-PCL-b-PMOXA). The synthesis is free of toxic reagents, well-controlled and results in polymers with D-M < 1.25 and PMOXA length up to 25 units (2 kDa). We compare the self assembly of PEO-b-PCL-b-PMOXA with PEO-b-PCL depending on PCL length and hydrophilic weight fraction (f) using the film rehydration method. Polymers self-assemble into different microscale structures, including polymersomes, which were studied by laser scanning microscopy. We proved the asymmetry of polymersome membrane by two independent methods, which confirmed the presence of a longer PEO block and the absence of a shorter PMOXA block on the outer surface of polymersomes.