Many of current research strategies in polymer science are inspired by the functioning of living systems in creating innovative technologies for medicine, industry and various other fields. In this view, the potential of poly(2-alkyl-2-oxazoline)s (PAOx) - that can be regarded as pseudo-polypeptides - has been explored in a wide array of applications, ranging from biomedical applications via additives for (paper) coatings to solid poly-electrolytes for Li-ion batteries.1 However, up to now bulk material applications of PAOx have remained largely unexplored, mainly due to limited synthetic accessibility of high molar mass PAOx, resulting in poor mechanical properties.2 This research shows that suitable side-chain functionalization leads to PAOx that exhibit interesting properties for use in high performance bulk materials, i.e.high melting temperatures, high thermal stability and solvent resistance. To this end, a range of poly(2-cycloalkyl-2-oxazoline)s were synthesized and their physico-chemical properties were investigated (Figure 1).                                                Figure 1.  Cationic ring-opening polymerization of poly(2-oxazoline)s (top) and 2-cycloalkyl-2oxazolines used in this study (bottom).Firstly, the kinetics of the different homopolymerizations of the 2-cycloalkyl-2-oxazolines shown in Figure 1 was studied, proving that the polymerizations proceed in both a living and controlled manner. Moreover, the kinetics revealed substituent dependence of the polymerization rate constant (kp), with an unexpectedly high kp value for 2-cyclopropyl-2-oxazoline ascribed to a higher monomer nucleophilicity by molecular modeling.3Poly(2-cyclobutyl-2-oxazoline), poly(2-cyclopentyl-2-oxazoline) and poly(2-cyclohexyl-2-oxazoline) showed thermal stability up to 350 �C and melting temperatures between 250 �C � 330 �C. The melting temperature could be further fine-tuned by copolymerization of 2-cyclopentyl-2-oxazoline with 2-ethyl-2-oxazoline or 2-butyl-2-oxazoline with varying monomer ratios.References1. (a) Luxenhofer, R.; Han, Y.; Schulz , A.; Tong, J.; He , Z.; Kabanov , A.V.; Jordan, R. Macromol. Rapid Commun. 2012  , 33, 1613-1631. (b) de la Rosa, V.R. J. Mater. Sci: Mater. Med. 2014  , DOI 10.1007/s10856-013-5034-y. (c) Hoogenboom R. Angew. Chem. Int. Ed. 2009  , 48, 7978-994.2. J. M. Kranenburg, C. A. Tweedie, R. Hoogenboom, F. Wiesbrock, H. M. L. Thijs, C. E. Hendriks, K. J. Van Vliet, U. S. Schubert, J. Mater. Chem. 2007  , 17, 2713-2721.3. H. Goossens, S. Catak, M. Glassner, V. de la Rosa, B. Monnery, F. De Proft, V. Van Speybroeck, R. Hoogenboom, ACS Macro Lett. 2013,   2, 651.

Poly(2-cycloalkyl-2-oxazoline)s with potential for high performance bulk materials

248th National Meeting (2014)

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