1. Glass-like dynamics of the strain-induced coil/helix transition on a permanent polymer network.
- Author
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Ronsin, O., Caroli, C., and Baumberger, T.
- Subjects
- *
POLYMERS , *GELATIN , *CHEMICAL relaxation , *COVALENT bonds , *ISOMERIZATION , *MOLECULAR dynamics - Abstract
We study the stress response to a step strain of covalently bonded gelatin gels in the temperature range where triple helix reversible crosslink formation is prohibited. We observe slow stress relaxation towards a T-dependent finite asymptotic level. We show that this is assignable to the strain-induced coil → helix transition, previously evidenced by Courty et al. [Proc. Natl. Acad. Sci. U. S. A. 102, 13457 (2005)], of a fraction of the polymer strands. Relaxation proceeds, in a first stage, according to a stretched exponential dynamics, then crosses over to a terminal simple exponential decay. The respective characteristic times TK and Tf exhibit an Arrhenius-like T-dependence with an associated energy E incompatibly larger than the activation barrier height for the isomerisation process which sets the clock for an elementary coil → helix transformation event. We tentatively assign this glass-like slowing down of the dynamics to the long-range couplings due to the mechanical noise generated by the local elementary events in this random elastic medium. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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