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In Macromol. Rapid Commun. (together with the Ling lab): Heterograft Molecular Polymer Brushes!

Janus polymerization is a novel and efficient way to synthesize diblock and multiblock copolymers in one step by using Lu(OTf)3 and propylene epoxide as catalytic system. By modifying the epoxide initiator which is located at the block junction with various functional groups, the possibility for future topological design is provided. Herein, we use 2-bicyclo[2.2.1]hept-5-en-2-yl oxirane (NB-EO) as alternative for propylene epoxide to synthesize a poly(THF-co-CL)-b-PCL diblock copolymer featuring a norbornene group at this position. This also results in multiblock [poly(THF-co-CL)-b-PCL]m copolymers carrying multiple norbornene moieties through Janus polymerization. Subsequent ring-opening metathesis copolymerization (ROMP) of the resulting poly(THF-co-CL)-b-PCL macromonomers with norbornenyl-terminated polysarcosine (PSar-NB) allows the facile preparation of heterograft molecular polymer brushes (MPBs). The MPBs feature three heterografts of PCL, P(CL-co-THF) and PSar, potentially equipping these structures with biocompatibility, biodegradability, semi-crystallinity and amphiphilicity. We observe phase separation after annealing in both TEM and AFM analysis. Due to their amphiphilic nature, the MPBs also undergo self-assembly into micelles in aqueous solution. Such materials combining polypeptoids, polyesters, and polyether segments are expected to attract wide attention in drug delivery applications.

Original Article:

Y. Li, F. H. Schacher, J. Ling, "Synthesis of Polypeptoid-Polycaprolactone-Polytetrahydrofuran Heterograft Molecular Polymer Brushes via a Combination of Janus Polymerization and ROMP", Macromo. Rapid Commun. 2019, in press

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