We report a new family of amphiphilic ABC triblock copolymers, poly(ethylene oxide)-block-polycaprolactone-block-poly(2-methyl-2-oxazoline) (PEO-b-PCL-b-PMOXA). The synthesis is free of toxic reagents, well-controlled, and result in polymers with Ð 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 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.

Sequence-defined oligourethanes were tested as in vivo taggants for implant identification. The oligomers were prepared in an orthogonal solid-phase iterative approach and thus contained a coded monomer sequence that can be unequivocally identified by tandem mass spectrometry (MS/MS). The oligomers were then included in small amounts (1 wt %) in square-centimeter-sized crosslinked poly(vinyl alcohol) (PVA) model films, which were intramuscularly and subcutaneously implanted in the abdomen of rats. After one week, one month, or three months of implantation, the PVA films were explanted. The rat tissues exposed to the implants did not exhibit any adverse reactions, which suggested that the taggants are not harmful and probably not leaching out from the films. Furthermore, the explanted films were immersed in methanol, as a solvent for oligourethanes, and the liquid extract was analyzed by mass spectrometry. In all cases, the oligourethane taggant was detected, and its sequence was identified by MS/MS.

Poly(ethylene oxide)-block-polycaprolactone (PEO-b-PCL) is one of the widely used biocompatible amphiphilic block copolymers which is able to self-assemble into a variety of 3D structures, including polymersomes. Controlled self-assembly into a 3D structure with a certain size and morphology might require uniform PEO-b-PCL (Đ M < 1.1), which has not been possible to synthesize so far. In this work, we optimized the well-known synthesis of PEOb-PCL, catalyzed by SnOct 2 , leading to a low molecular-weight dispersity (< 1.1), and discussed the aging effects of SnOct 2 on the overall kinetics of the synthesis. To understand the effect of the dispersity of PEO-b-PCL on its self-assembly, we compared self-assembled structures formed by uniform PEO-b-PCL (Đ M < 1.1) with the ones formed by non-uniform analogues (Đ M > 1.1). Furthermore, we demonstrated the benefits of uniform PEO-b-PCL when a high degree of end-group activation is required through ω-tosylation.