Knots “choke off” polymers upon stretching

• Verfasst von: Stauch, Tim [VerfasserIn]
• Verfasst von: Dreuw, Andreas [VerfasserIn]
• Titel: Knots “choke off” polymers upon stretching
• Verf.angabe: Tim Stauch and Andreas Dreuw
• Umfang: 4 S.
• Fussnoten: First published: 2 December 2015 ; Gesehen am 07.12.2017
• Titel Quelle: Enthalten in: Angewandte Chemie / International edition
• Jahr Quelle: 2016
• Band/Heft Quelle: 55(2016), 2, S. 811-814
• ISSN Quelle: 1521-3773
• DOI: doi:10.1002/anie.201508706
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1566134137

Abstract

Long polymer chains inevitably get tangled into knots. Like macroscopic ropes, polymer chains are substantially weakened by knots and the rupture point is always located at the “entry” or “exit” of the knot. However, these phenomena are only poorly understood at a molecular level. Here we show that when a knotted polyethylene chain is tightened, most of the stress energy is stored in torsions around the curved part of the chain. The torsions act as “work funnels” that effectively localize mechanical stress in the immediate vicinity of the knot. As a result, the knot “chokes” the chain at its entry or exit, thus leading to bond rupture at much lower forces than those needed to break a linear, unknotted chain. Our work not only explains the weakening of the polymer chain and the position of the rupture point, but more generally demonstrates that chemical bonds do not have to be extensively stretched to be broken.