Aug 2026· ACS Macro Letters· 0 citations· 40 references
Abstract
We combine dielectric and viscoelastic measurements with novel statistical mechanical theories to establish and understand strong decoupling of cation activated dynamics from the polymer segmental relaxation in polymerized ionic liquids. Weakly ion-dependent (Li, Na, K) apparent power laws with fractional exponents between the two characteristic time scales (ionic and segmental) are observed and predicted in the supercooled regime. The ratio of segmental to ion relaxation times grows in a strongly non-Arrhenius manner with cooling. However, at high (fast) enough temperature (segmental relaxation), the theory predicts that decoupling continuously vanishes, and a linear Walden-like proportionality between the two relaxation times is recovered. The theoretical analysis spans 20 decades in time, including the glass state. The mechanistic key to the rich dynamics is the extent to which ion-activated barrier crossing is coupled with in-cage local polymer dynamical fluctuations that facilitate ion hopping.
We extend the microscopic self-consistent cooperative hopping theory (SCCHT) of activated ion dynamics in polymerized ionic liquids (PolyILs) and glasses based on a trained polymer physics model to provide an understanding of the effect of cation size on the physical barrier and ion relaxation time as a function of t...
Ankita Das, Kenneth S. Schweizer· Macromolecules· 1 citation
Pre-stretching raises the glass transition temperature (Tg) of polymers, yet the underlying microscopic mechanisms remain unclear. This work employs molecular dynamics simulations of polymer systems with different entanglement densities (Ne) to unravel this mechanism. The simulations reproduce the experimentally observ...
Hao Sun, Ren-Kuan Cao, Yun-Han Zhang et al.· Journal of Chemical Physics· 0 citations
We investigate the slowing down of dynamics in a glass-forming mixture interacting via an inverse-power-law (IPL) potential using a combination of theory and large-scale molecular dynamics simulations. We measure the static pair-correlation function, configurational entropy, inherent-structure energy, and structural re...
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Thin polymer films are archetypal nonequilibrium systems in which chain conformations are frozen by rapid preparation. The resulting molecular recoiling stress drives the system toward equilibrium and relaxes with time and temperature. We show that the activation energy governing this relaxation depends on the magnitud...
: Cellulose-based gel polymer electrolytes (GPEs) are promising sustainable candidates for next-generation lithium batteries; however, the relationship between polymer dynamics and ion transport remains insufficiently understood. In this study, cellulose-based GPEs with varying lithium salt concentrations and crosslink...
Ruo-Xi Zhang, Rong-Zu Sun, Zhou Wei et al.· Journal of Polymer Materials· 0 citations
On cooling liquids towards their glass-transition temperature, the dramatic increase of their relaxation times is accompanied by changes in particle dynamics at two distinct temperatures: A high-T crossover, where particles become temporarily caged by their neighbors, and a low-T crossover, where the cage escape mechan...
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