RT Journal Article
SR Electronic
T1 Rheo-2DIR spectroscopy reveals strain-induced hydrogen-bond redistribution in polyurethane
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.10.04.510759
DO 10.1101/2022.10.04.510759
A1 Giubertoni, Giulia
A1 Hilbers, Michiel
A1 Groen, Hajo
A1 Van der Weide, Anne
A1 Bonn, Daniel
A1 Woutersen, Sander
YR 2022
UL http://biorxiv.org/content/early/2022/10/04/2022.10.04.510759.abstract
AB The remarkable elastic properties of polymers are ultimately due to their molecular structure, but the relation between the macroscopic and molecular properties is often difficult to establish, in particular for (bio)polymers that contain hydrogen bonds, which can easily rearrange upon mechanical deformation. Here we show that two-dimensional infrared spectroscopy on polymer films in a miniature stress tester sheds new light on how the hydrogen-bond structure of a polymer is related to its visco-elastic response. We study thermoplastic polyurethane, a block copolymer consisting of hard segments of hydrogen-bonded urethane groups embedded in a soft matrix of polyether chains. The conventional infrared spectrum shows that upon deformation, the number of hydrogen bonds increases, a process that is largely reversible. However, the 2DIR spectrum reveals that the distribution hydrogen-bond strengths becomes slightly narrower after a deformation cycle, due to the disruption of weak hydrogen bonds, an effect that could explain the strain-cycle induced softening (Mullins effect) of polyurethane. These results show how rheo-2DIR spectroscopy can bridge the gap between the molecular structure and the macroscopic elastic properties of (bio)polymers.Competing Interest StatementThe authors have declared no competing interest.