Combined Molecular Dynamics Simulation and Rouse Model Analysis of Static and Dynamic Properties of Unentangled Polymer Melts with Different Chain Architectures

Non-Rouse behavior of short ring polymers in melts by molecular dynamics simulations

“…1 The important practical implications of ring polymers, as well as the dramatic differences in their static properties and dynamical behaviors from linear polymers, prompt polymer scientists to focus on the relationship between the topology of a polymer and its physical properties. 2–12…”

“…In this work, to explore the non-Rouse behavior of flexible short non-concatenated and unknotted ring polymer melts with N < 2 N e , the dynamic and static properties of ring polymer melts are investigated by MD simulations with the standard Kremer–Grest model. 2 A detailed comparison with the corresponding simulation data from linear analogues and the predictions of the Rouse theory are made in order to systematically evaluate deviations and uncover the underlying mechanisms. Furthermore, to reveal the effect of topological constraints on the structure and dynamics of ring melts, both ring and linear polymers with switched off topological constraints are simulated and compared to those with the KG model.…”

“…1 The important practical implications of ring polymers, as well as the dramatic differences in their static properties and dynamical behaviors from linear polymers, prompt polymer scientists to focus on the relationship between the topology of a polymer and its physical properties. [2][3][4][5][6][7][8][9][10][11][12] For unentangled polymer melts, the Rouse model is expected to provide a reasonable description of polymer dynamics on length scales beyond the monomer size, wherein the excluded volume (EV) and hydrodynamic interactions are assumed to be screened and as a consequence, the ideal chain behavior is expected. [2][3][4]13,14 In practice, for flexible linear unentangled polymers, serious deviations from the Rouse picture are reported due to the EV or hydrodynamic interactions not completely screened in melts, i.e., the increase of the reduced mean square internal distance (MSID) with the size of polymer segments, 15,16 the sub-diffusive center-of-mass (c.m.)…”

“…[2][3][4][5][6][7][8][9][10][11][12] For unentangled polymer melts, the Rouse model is expected to provide a reasonable description of polymer dynamics on length scales beyond the monomer size, wherein the excluded volume (EV) and hydrodynamic interactions are assumed to be screened and as a consequence, the ideal chain behavior is expected. [2][3][4]13,14 In practice, for flexible linear unentangled polymers, serious deviations from the Rouse picture are reported due to the EV or hydrodynamic interactions not completely screened in melts, i.e., the increase of the reduced mean square internal distance (MSID) with the size of polymer segments, 15,16 the sub-diffusive center-of-mass (c.m.) motion, [17][18][19] and so on.…”

“…For non-concatenated and non-knotted ring polymers lacking chain ends, as the topological constraints are commonly considered to be important only for rings with a chain length (N) longer than twice the entanglement length (N e ) of the linear polymer, the dynamics and chain dimension of short rings in melts are expected to be nearly Rouse-like. 12,20,21 Although deviations from the Rouse prediction are reported in the literature, 2,4,7,22 systematic investigations of non-Rouse behaviors of flexible short rings are scarce. In-depth research of this kind represents a useful starting point for a full understanding of the structural and dynamic properties of ring polymer melts and for the development of improved Rouse theory or more realistic models, which has remained as one of the main challenges in polymer science.…”