Synthesis, aggregation and crystallization of precision polymers with repetitive folding elements

M. B. Canalp, J. Freudenberg, S. Reimann and W. H. Binder

Martin Luther University Halle-Wittenberg, Faculty of Natural Sciences II, Chair of Macromolecular Chemistry, Von-Danckelmann-Platz 4, D-06120 Halle

The investigation of ordering phenomena in biological and synthetic macromolecules still presents an interesting and promising field of research. Biological macromolecules form stable secondary or higher structures via inter- and intramolecular ordering processes, which are based on the interaction of their precisely placed amino-acids and the rotational constraints resulting from the peptide bonds. [1] Especially the understanding of the secondary structure formation from polypeptides is essential as it depends strongly on their (bio)chemical environment.
We investigate the aggregation and crystallization behavior of different precision polymers, which are characterized by repeating sequences of synthetic polyolefins and different biomimetic structure-elements. Constraints like 2,6-diaminopyridine and urea induce a conformational restriction while poly(amino acids) like poly-L-glutamic acid, poly-L-aspartic acid, poly-L-lysine and poly-L-leucine display a large conformational variability and dynamic α-helical-to-coil-transition. [2] All included moieties additionally interact with each other via supramolecular interactions influencing the crystallization behavior of the polyethylene chain. Therefore, acyclic diene metathesis (ADMET) polymerization was used to achieve a periodic incorporation of the constraint into the polymer backbone, resulting in precision polymers, which were analyzed via DSC and WAXS measurements. [3]

[1] C. B. H. Anfinsen, E., J. Biol. Chem. 1961, 236, 1361. (link)
[2] P. Novotná, M. Urbanová Vib. Spectrosc. 2013, 66, 1. (link)
[3] S. Reimann, U. Baumeister, W. H. Binder, Macromol. Chem. Phys. 2014, 215, 1963. (link)