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Determining Tube Theory Parameters by Slip-Spring Model Simulations of Entangled Star Polymers in Fixed Networks

Dynamical properties of branched polymer melts are determined by the polymer molecular weights and architectures containing junction points. Relaxation of entangled symmetric star polymers proceeds via arm-retraction and constraint release (CR). In this work, we investigate arm-retraction dynamics i...

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Autores principales: Cao, Jing, Wang, Zuowei, Likhtman, Alexei E.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6473678/
https://www.ncbi.nlm.nih.gov/pubmed/30960480
http://dx.doi.org/10.3390/polym11030496
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author Cao, Jing
Wang, Zuowei
Likhtman, Alexei E.
author_facet Cao, Jing
Wang, Zuowei
Likhtman, Alexei E.
author_sort Cao, Jing
collection PubMed
description Dynamical properties of branched polymer melts are determined by the polymer molecular weights and architectures containing junction points. Relaxation of entangled symmetric star polymers proceeds via arm-retraction and constraint release (CR). In this work, we investigate arm-retraction dynamics in the framework of a single-chain slip-spring model without CR effect where entanglements are treated as binary contacts, conveniently modeled as virtual “slip-links”, each involving two neighboring strands. The model systems are analogous to isolated star polymers confined in a permanent network or a melt of very long linear polymers. We find that the distributions of the effective primitive path lengths are Gaussian, from which the entanglement molecular weight [Formula: see text] , a key tube theory parameter, can be extracted. The procured [Formula: see text] value is in good agreement with that obtained from mapping the middle monomer mean-square displacements of entangled linear chains in slip-spring model to the tube model prediction. Furthermore, the mean first-passage (FP) times of destruction of original tube segments by the retracting arm end are collected in simulations and examined quantitatively using a theory recently developed in our group for describing FP problems of one-dimensional Rouse chains with improbable extensions. The asymptotic values of [Formula: see text] as obtained from the static (primitive path length) and dynamical (FP time) analysis are consistent with each other. Additionally, we manage to determine the tube survival function of star arms [Formula: see text] , or equivalently arm end-to-end vector relaxation function [Formula: see text] , through the mean FP time spectrum [Formula: see text] of the tube segments after careful consideration of the inner-most entanglements, which shows reasonably good agreement with experimental data on dielectric relaxation.
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spelling pubmed-64736782019-05-03 Determining Tube Theory Parameters by Slip-Spring Model Simulations of Entangled Star Polymers in Fixed Networks Cao, Jing Wang, Zuowei Likhtman, Alexei E. Polymers (Basel) Article Dynamical properties of branched polymer melts are determined by the polymer molecular weights and architectures containing junction points. Relaxation of entangled symmetric star polymers proceeds via arm-retraction and constraint release (CR). In this work, we investigate arm-retraction dynamics in the framework of a single-chain slip-spring model without CR effect where entanglements are treated as binary contacts, conveniently modeled as virtual “slip-links”, each involving two neighboring strands. The model systems are analogous to isolated star polymers confined in a permanent network or a melt of very long linear polymers. We find that the distributions of the effective primitive path lengths are Gaussian, from which the entanglement molecular weight [Formula: see text] , a key tube theory parameter, can be extracted. The procured [Formula: see text] value is in good agreement with that obtained from mapping the middle monomer mean-square displacements of entangled linear chains in slip-spring model to the tube model prediction. Furthermore, the mean first-passage (FP) times of destruction of original tube segments by the retracting arm end are collected in simulations and examined quantitatively using a theory recently developed in our group for describing FP problems of one-dimensional Rouse chains with improbable extensions. The asymptotic values of [Formula: see text] as obtained from the static (primitive path length) and dynamical (FP time) analysis are consistent with each other. Additionally, we manage to determine the tube survival function of star arms [Formula: see text] , or equivalently arm end-to-end vector relaxation function [Formula: see text] , through the mean FP time spectrum [Formula: see text] of the tube segments after careful consideration of the inner-most entanglements, which shows reasonably good agreement with experimental data on dielectric relaxation. MDPI 2019-03-14 /pmc/articles/PMC6473678/ /pubmed/30960480 http://dx.doi.org/10.3390/polym11030496 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Cao, Jing
Wang, Zuowei
Likhtman, Alexei E.
Determining Tube Theory Parameters by Slip-Spring Model Simulations of Entangled Star Polymers in Fixed Networks
title Determining Tube Theory Parameters by Slip-Spring Model Simulations of Entangled Star Polymers in Fixed Networks
title_full Determining Tube Theory Parameters by Slip-Spring Model Simulations of Entangled Star Polymers in Fixed Networks
title_fullStr Determining Tube Theory Parameters by Slip-Spring Model Simulations of Entangled Star Polymers in Fixed Networks
title_full_unstemmed Determining Tube Theory Parameters by Slip-Spring Model Simulations of Entangled Star Polymers in Fixed Networks
title_short Determining Tube Theory Parameters by Slip-Spring Model Simulations of Entangled Star Polymers in Fixed Networks
title_sort determining tube theory parameters by slip-spring model simulations of entangled star polymers in fixed networks
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6473678/
https://www.ncbi.nlm.nih.gov/pubmed/30960480
http://dx.doi.org/10.3390/polym11030496
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