Monnery Bryn D, Jerca Valentin V, Sedlacek Ondrej, Verbraeken Bart, Cavill Rachel, Hoogenboom Richard
Supramolecular Chemistry Group, Centre of Macromolecular Chemistry (CMaC), Department of Organic and Macromolecular Chemistry, Ghent University, Krijgslaan 281-S4, 9000, Gent, Belgium.
Centre of Organic Chemistry "Costin D. Nenitzescu", Romanian Academy, Spl. Independentei 202B, 060023, Bucharest, Romania.
Angew Chem Int Ed Engl. 2018 Nov 19;57(47):15400-15404. doi: 10.1002/anie.201807796. Epub 2018 Oct 30.
Poly(2-alkyl-2-oxazoline)s (PAOx) are regaining interest for biomedical applications. However, their full potential is hampered by the inability to synthesise uniform high-molar mass PAOx. In this work, we proposed alternative intrinsic chain transfer mechanisms based on 2-oxazoline and oxazolinium chain-end tautomerisation and derived improved polymerization conditions to suppress chain transfer, allowing the synthesis of highly defined poly(2-ethyl-2-oxazoline)s up to ca. 50 kDa (dispersity (Ð) <1.05) and defined polymers up to at least 300 kDa (Ð<1.2). The determination of the chain transfer constants for the polymerisations hinted towards the tautomerisation of the oxazolinium chain end as most plausible cause for chain transfer. Finally, the method was applied for the preparation of up to 60 kDa molar mass copolymers of 2-ethyl-2-oxazoline and 2-methoxycarbonylethyl-2-oxazoline.
聚（2-烷基-2-恶唑啉）（PAOx）在生物医学应用方面正重新引起人们的关注。然而，由于无法合成具有均匀高分子量的PAOx，其全部潜力受到了限制。在这项工作中，我们基于2-恶唑啉和恶唑啉鎓链端互变异构提出了替代的内在链转移机制，并推导了改进的聚合条件以抑制链转移，从而能够合成高达约50 kDa（分散度（Ð）<1.05）的高度规整的聚（2-乙基-2-恶唑啉）以及至少300 kDa（Ð<1.2）的规整聚合物。对聚合反应链转移常数的测定表明，恶唑啉鎓链端的互变异构是最有可能导致链转移的原因。最后，该方法被用于制备分子量高达60 kDa的2-乙基-2-恶唑啉和2-甲氧基羰基乙基-2-恶唑啉的共聚物。
