Interaction-Dependent Molecular Probing of Heterogeneous Glassy Dynamics in Polymer Melts
Abstract
Single-molecule probes are widely used to characterize dynamic heterogeneity in glass-forming liquids, but their measured dynamics can depend on how the probe couples to its host environment. Using molecular dynamics simulations of dilute dimer probes embedded in a supercooled polymer melt, we examine how probe--host affinity influences the correspondence between probe rotational relaxation and host dynamics. Increasing the probe--host interaction strength systematically modifies the relative temperature dependence of probe and host relaxation while leaving the intrinsic host dynamics essentially unperturbed. Lower-affinity probes exhibit stronger non-Gaussian translational motion and larger displacement fluctuations, whereas higher-affinity probes remain more localized and are statistically less exposed to the most dynamically active host environments. Comparison with wavevector-dependent host structural relaxation further identifies an effective matching wavevector at which the host structural relaxation exhibits the temperature dependence most similar to that of the probe, providing a phenomenological measure of the probe--host dynamical correspondence. Together with real-space analyses of the local environments sampled by the probe, these results show that probe--host affinity systematically influences the quantitative relationship between molecular-probe relaxation and heterogeneous host dynamics.
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BibTeX
@misc{kim2026interactiondependent,
title = {{Interaction-Dependent Molecular Probing of Heterogeneous Glassy Dynamics in Polymer Melts}},
author = {Suyeon Kim and Taejin Kwon},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.21298},
eprint = {2605.21298},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.21298},
}
RIS
TY - UNPB
TI - Interaction-Dependent Molecular Probing of Heterogeneous Glassy Dynamics in Polymer Melts
AU - Suyeon Kim
AU - Taejin Kwon
PY - 2026
DA - 2026/09/26
PB - arXiv
DO - 10.48550/arxiv.2605.21298
UR - https://arxiv.org/abs/2605.21298
AB - Single-molecule probes are widely used to characterize dynamic heterogeneity in glass-forming liquids, but their measured dynamics can depend on how the probe couples to its host environment. Using molecular dynamics simulations of dilute dimer probes embedded in a supercooled polymer melt, we examine how probe--host affinity influences the correspondence between probe rotational relaxation and host dynamics. Increasing the probe--host interaction strength systematically modifies the relative temperature dependence of probe and host relaxation while leaving the intrinsic host dynamics essentially unperturbed. Lower-affinity probes exhibit stronger non-Gaussian translational motion and larger displacement fluctuations, whereas higher-affinity probes remain more localized and are statistically less exposed to the most dynamically active host environments. Comparison with wavevector-dependent host structural relaxation further identifies an effective matching wavevector at which the host structural relaxation exhibits the temperature dependence most similar to that of the probe, providing a phenomenological measure of the probe--host dynamical correspondence. Together with real-space analyses of the local environments sampled by the probe, these results show that probe--host affinity systematically influences the quantitative relationship between molecular-probe relaxation and heterogeneous host dynamics.
ER -