Force-dependent bond dissociation explains the rate-dependent fracture of vitrimers

Zhaoqiang Song; Tong Shen; Franck J Vernerey; Shengqiang Cai

doi:10.1039/d1sm00518a

Force-dependent bond dissociation explains the rate-dependent fracture of vitrimers

Soft Matter. 2021 Jul 14;17(27):6669-6674. doi: 10.1039/d1sm00518a.

Authors

Zhaoqiang Song¹, Tong Shen², Franck J Vernerey³, Shengqiang Cai⁴

Affiliations

¹ Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093, USA. shqcai@ucsd.edu.
² Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO 80302, USA. franck.vernerey@colorado.edu.
³ Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO 80302, USA. franck.vernerey@colorado.edu and Program of Materials Science and Engineering, University of Colorado Boulder, Boulder, CO 80302, USA.
⁴ Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093, USA. shqcai@ucsd.edu and Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093, USA.

PMID: 34179917
DOI: 10.1039/d1sm00518a

Abstract

We investigate the rate-dependent fracture of vitrimers by conducting a tear test. Based on the relationship between the fracture energy and the thickness of vitrimer films, we, for the first time, obtain the intrinsic fracture energy and bulk dissipation of vitrimers during crack extension. The intrinsic fracture energy strongly depends on tear speed, and such dependence can be well explained by Eyring theory. In contrast, the bulk dissipation only weakly depends on tear speed, which is drastically different from observations on traditional viscoelastic polymers. We ascribe such a weak rate-dependence to the strong force-sensitivity of the exchange reaction of the dynamic covalent bond in the vitrimer.