Poly(2-alkyl-2-oxazoline)s (PAOx) are biocompatible pseudo-polypeptides that received significant interest for biomedical applications in recent years. This popularity of PAOx is also driven by the fact that its chemical reactivity and versatility is much higher compared to the gold standard in this field, poly(ethylene glycol) (PEG), while the biocompatibility and the stealth behaviour of PAOx and PEG are similar. The introduction of functionalities is crucial for further applications in a biomedical context. Here, we report a synthetic methodology to further expand the chemical versatility of PAOx based on a straightforward post-polymerization modification platform. At first, controlled partial hydrolysis of poly(2-ethyl-2-oxazoline) (PEtOx) is performed resulting in a copolymer of PEtOx and poly(ethylene imine) (PEI). Subsequently, side-chain methyl ester groups are introduced, via addition of various methyl ester containing electrophiles, including bromo acetate, methyl-chlorosuccinate and methoxycarbonyl ethyliso(thio)cyanate to the secondary amine groups of PEtOx-PEI. Alternatively, copolymerization of 2-methoxycarbonylethyl-2-oxazoline with PEtOx also led to similar copolymers with methyl ester groups in the side chains. The incorporated methyl ester groups are demonstrated to be versatile for further modification by direct transamidation with a wide variety of different amines as is demonstrated by introducing a range of side-chain functionalities including acid, amine, alcohol, hydrazide and propargyl groups.

Straightforward post modification of poly(2-ethyl-2-oxazoline) by transamidation of side chain methyl ester groups

248th National Meeting (2014)

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