Hyperbranched polyglycerol (hbPG) is synthesized via anionic ring-opening multi-branching polymerization (ROMBP) of glycidol, a latent AB2 oxirane. It is a highly versatile polymer due to its excellent water-solubility and biocompatibility, enabling its use in biomedical applications.1 Additionally, the high number of hydroxyl groups allows for further functionalization and derivatization of the polymers. However, the direct introduction of additional functionalities into the polymer is rather difficult, because it requires carefully chosen comonomers with (protected) functional groups that withstand the harsh, basic polymerization conditions. Additionally, reaction conditions need to be adjusted for every single copolymer system resulting in considerable synthetic effort.2Here, we present a platform-based approach to overcome these problems using furfuryl glycidyl ether (FGE) as a comonomer. Subsequent Diels-Alder �click� reaction3 with functional maleimide derivatives allows for reversible introduction of functional groups that can be controlled by temperature. We were able to reversibly introduce allyl, alkyne, catechol, amine and acid groups. These functionalities enable post-polymerization modifications orthogonal to the hydroxyl groups and demonstrate the high versatility of the concept. HbPGs with molecular weights between 2000 and 7000 g mol-1 and different comonomer contents (4 to 18 mol%) were obtained. Polydispersity indices (PDI) are moderate to narrow (1.34 to 1.81). Quantitative Diels-Alder reaction of furfuryl groups with functional maleimides was proven by 2D NMR experiments and SEC measurements.In conclusion, we have introduced a novel construction kit for the reversible temperature-controlled functionalization of hbPG which may open pathways to a plethora of further applications in different areas.[1] D. Wilms, S.-E. Stiriba, H. Frey, Acc. Chem. Res. 2010,  43, 129-141.[2] C. Sch�ll, T. Gieshoff, H. Frey, Polym. Chem. 2013,  4, 4730-4736.[3] H. C. Kolb, M. G. Finn, K. B. Sharpless, Angew. Chem. Int. Ed. 2001,  40, 2004-2021.

Hetero-multifunctional polyglycerols: Temperature-controlled reversible introduction of functional groups

248th National Meeting (2014)

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