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Title: Structure and dynamics of confined flexible and unentangled polymer melts in highly adsorbing cylindrical pores

Abstract

Coarse-grained molecular dynamics simulations are used to probe the dynamic phenomena of polymer melts confined in nanopores. The simulation results show excellent agreement in the values obtained for the normalized coherent single chain dynamic structure factor, S(Q,t) S(Q,0) . In the bulk configuration, both simulations and experiments confirm that the polymer chains follow Rouse dynamics. However, under confinement, the Rouse modes are suppressed. The mean-square radius of gyration R2 g and the average relative shape anisotropy κ2 of the conformation of the polymer chains indicate a pancake-like conformation near the surface and a bulk-like conformation near the center of the confining cylinder. This was confirmed by direct visualization of the polymer chains. Despite the presence of these different conformations, the average form factor of the confined chains still follows the Debye function which describes linear ideal chains, which is in agreement with small angle neutron scattering experiments (SANS). The experimentally inaccessible mean-square displacement (MSD) of the confined monomers, calculated as a function of radial distance from the pore surface, was obtained in the simulations. The simulations show a gradual increase of the MSD from the adsorbed, but mobile layer, to that similar to the bulk far away from the surface.

Authors:
ORCiD logo [1]; ORCiD logo [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1159493
DOE Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 141; Journal Issue: 7
Country of Publication:
United States
Language:
English

Citation Formats

Carrillo, Jan-Michael Y., and Sumpter, Bobby G.. Structure and dynamics of confined flexible and unentangled polymer melts in highly adsorbing cylindrical pores. United States: N. p., 2014. Web. doi:10.1063/1.4893055.
Carrillo, Jan-Michael Y., & Sumpter, Bobby G.. Structure and dynamics of confined flexible and unentangled polymer melts in highly adsorbing cylindrical pores. United States. doi:10.1063/1.4893055.
Carrillo, Jan-Michael Y., and Sumpter, Bobby G.. Fri . "Structure and dynamics of confined flexible and unentangled polymer melts in highly adsorbing cylindrical pores". United States. doi:10.1063/1.4893055.
@article{osti_1159493,
title = {Structure and dynamics of confined flexible and unentangled polymer melts in highly adsorbing cylindrical pores},
author = {Carrillo, Jan-Michael Y. and Sumpter, Bobby G.},
abstractNote = {Coarse-grained molecular dynamics simulations are used to probe the dynamic phenomena of polymer melts confined in nanopores. The simulation results show excellent agreement in the values obtained for the normalized coherent single chain dynamic structure factor, S(Q,t) S(Q,0) . In the bulk configuration, both simulations and experiments confirm that the polymer chains follow Rouse dynamics. However, under confinement, the Rouse modes are suppressed. The mean-square radius of gyration R2 g and the average relative shape anisotropy κ2 of the conformation of the polymer chains indicate a pancake-like conformation near the surface and a bulk-like conformation near the center of the confining cylinder. This was confirmed by direct visualization of the polymer chains. Despite the presence of these different conformations, the average form factor of the confined chains still follows the Debye function which describes linear ideal chains, which is in agreement with small angle neutron scattering experiments (SANS). The experimentally inaccessible mean-square displacement (MSD) of the confined monomers, calculated as a function of radial distance from the pore surface, was obtained in the simulations. The simulations show a gradual increase of the MSD from the adsorbed, but mobile layer, to that similar to the bulk far away from the surface.},
doi = {10.1063/1.4893055},
journal = {Journal of Chemical Physics},
number = 7,
volume = 141,
place = {United States},
year = {Fri Aug 01 00:00:00 EDT 2014},
month = {Fri Aug 01 00:00:00 EDT 2014}
}