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Title: Conformation of Single Pentablock Ionomer Chains in Dilute Solutions

Abstract

The conformation of single chain pentablock ionomers (A-B-C-B-A) containing randomly sulfonated polystyrene in the center block, tethered to poly-ethylene-r-propylene end-capped by poly-t-butyl styrene is studied in dilute solutions by molecular dynamics simulations. Multi-block copolymers offer a means to tailor several properties into one molecule, taking advantage of their rich phase diagram together with unique properties of specific blocks. For this pentablock the ionic block facilitates transport while the A and B components are incorporated for mechanical stability. The present study investigates the confirmation of a single chain of pentablock ionomer of molecular weight M w ~ 50,000 g/mol and sulfonated polystyrene of the same molecular weight as that of the center block for six sulfonation fractions f from f=0.0-0.55. For the sulfonated systems Na + counterions are included. Results for the equilibrium conformation of the chains and the three blocks in water and 1:1 mixture of cyclohexane and n-heptane are compared to simulations in implicit poor solvents with dielectric constants ε =1.0 and 77.73. In water, the pentablock is collapsed with sulfonated groups on the outer surface. As the sulfonation fraction f increases, the ionic, center block is increasingly segregated from the hydrophobic regions. In the 1:1 mixture of cyclohexanemore » and heptane both the flexible and end blocks are swollen while the center ionic block is collasped for f>0, while for f=0 all blocks are swollen. In both implicit poor solvents the pentablock is collapsed into a nearly spherical shape for all f. The sodium counterions are dispersed widely throughout the simulation cell for both water and ε =77.73 whereas for ε =1.0 the counterions are largely condensed on the collapsed pentablock.« less

Authors:
 [1];  [1];  [2]
  1. Clemson Univ., SC (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1427257
Report Number(s):
SAND-2015-2579J
Journal ID: ISSN 9999-0014; 581948
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article
Journal Name:
Sandia journal manuscript; Not yet accepted for publication
Additional Journal Information:
Journal Name: Sandia journal manuscript; Not yet accepted for publication; Journal ID: ISSN 9999-0014
Publisher:
Sandia
Country of Publication:
United States
Language:
English

Citation Formats

Aryal, Dipak, Perahia, Dvora, and Grest, Gary S. Conformation of Single Pentablock Ionomer Chains in Dilute Solutions. United States: N. p., 2015. Web.
Aryal, Dipak, Perahia, Dvora, & Grest, Gary S. Conformation of Single Pentablock Ionomer Chains in Dilute Solutions. United States.
Aryal, Dipak, Perahia, Dvora, and Grest, Gary S. Wed . "Conformation of Single Pentablock Ionomer Chains in Dilute Solutions". United States. https://www.osti.gov/servlets/purl/1427257.
@article{osti_1427257,
title = {Conformation of Single Pentablock Ionomer Chains in Dilute Solutions},
author = {Aryal, Dipak and Perahia, Dvora and Grest, Gary S.},
abstractNote = {The conformation of single chain pentablock ionomers (A-B-C-B-A) containing randomly sulfonated polystyrene in the center block, tethered to poly-ethylene-r-propylene end-capped by poly-t-butyl styrene is studied in dilute solutions by molecular dynamics simulations. Multi-block copolymers offer a means to tailor several properties into one molecule, taking advantage of their rich phase diagram together with unique properties of specific blocks. For this pentablock the ionic block facilitates transport while the A and B components are incorporated for mechanical stability. The present study investigates the confirmation of a single chain of pentablock ionomer of molecular weight Mw ~ 50,000 g/mol and sulfonated polystyrene of the same molecular weight as that of the center block for six sulfonation fractions f from f=0.0-0.55. For the sulfonated systems Na+ counterions are included. Results for the equilibrium conformation of the chains and the three blocks in water and 1:1 mixture of cyclohexane and n-heptane are compared to simulations in implicit poor solvents with dielectric constants ε =1.0 and 77.73. In water, the pentablock is collapsed with sulfonated groups on the outer surface. As the sulfonation fraction f increases, the ionic, center block is increasingly segregated from the hydrophobic regions. In the 1:1 mixture of cyclohexane and heptane both the flexible and end blocks are swollen while the center ionic block is collasped for f>0, while for f=0 all blocks are swollen. In both implicit poor solvents the pentablock is collapsed into a nearly spherical shape for all f. The sodium counterions are dispersed widely throughout the simulation cell for both water and ε =77.73 whereas for ε =1.0 the counterions are largely condensed on the collapsed pentablock.},
doi = {},
url = {https://www.osti.gov/biblio/1427257}, journal = {Sandia journal manuscript; Not yet accepted for publication},
issn = {9999-0014},
number = ,
volume = ,
place = {United States},
year = {2015},
month = {4}
}