Modeling the Slow Arrhenius Process (SAP) in Polymers
Michigan State University（密歇根州立大学）；Technion（以色列理工学院）；Universite libre de Bruxelles (ULB)（布鲁塞尔自由大学）；Naval Research Laboratory（海军研究实验室）；University of Milan（米兰大学）
Valeriy V. Ginzburg, Oleg V. Gendelman, Simone Napolitano, Riccardo Casalini, Alessio Zaccone
备注：
Main text: 36 pages, 7 figures. Added Supporting Information: 12 pages, 11 figures. Will be submitted to Soft Matter
Amorphous glass-forming polymers exhibit multiple relaxation processes, including the structural α-relaxation associated with the glass transition and faster secondary relaxations that typically follow Arrhenius behavior. Recently, a distinct slow Arrhenius process (SAP) has been observed at frequencies well below the α-process. Although Arrhenian in its temperature dependence, the SAP involves much longer relaxation times and its microscopic origin remains unclear. Here, we extend the two-state, two-timescale (TS2) theory to describe both the α-relaxation and the SAP within a unified framework. We propose that the SAP represents the high-temperature limit of an α-like process in a coarse-grained fluid of dynamically correlated clusters. With renormalized interaction energies and coordination parameters, the same model quantitatively reproduces both α and SAP data across multiple polymers without additional adjustable parameters and explains the observed Meyer-Neldel compensation behavior. The theory further predicts that the SAP should deviate from Arrhenius behavior at sufficiently low temperatures, transitioning to Vogel-Fulcher-Tammann-Hesse-like dynamics, thereby offering a physically transparent interpretation of cluster-scale relaxation in glass-forming polymers.
Conformational and Structural Relaxations of Poly(ethylene oxide) and Poly(propylene oxide) Melts: Molecular Dynamics Study of Spatial Heterogeneity, Cooperativity, and Correlated Forward-Backward Motion
