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Friction 2014, 2(1): 73-81 https://doi.org/10.1007/s40544-014-0041-7
Research Article | Open Access | Issue | Published: 11 March 2014

Structure of polyelectrolyte brushes studied by coarse grain simulations

Show Author's Information Hitoshi WASHIZU1,2( ),  Tomoyuki KINJO1,2,  Hiroaki YOSHIDA1,2
Toyota Central R&D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan
Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, Katsura, Kyoto 615-8520, Japan
Keywords:
friction, polyelectrolyte brush, Monte Carlo Brownian dynamics simulation, soft materials, automotive tribology
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WASHIZU H, KINJO T, YOSHIDA H. Structure of polyelectrolyte brushes studied by coarse grain simulations. Friction, 2014, 2(1): 73-81. https://doi.org/10.1007/s40544-014-0041-7
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Abstract Full text About this article

As an example of a very low friction system, Monte Carlo Brownian dynamics simulations have been used to calculate equilibrium structures of a polyelectrolyte brush grafted onto planes. The polymers were calculated in a semi-flexible coarse-grain model that is appropriate to treat the charge density of the polyion. The effect of linear charge density on the polyion ξ, the surface negative charge, and added salts were studied. In salt-free solution, scaling theories predicted the structure well in the low ξ region. In the high ξ region, additional shrinkage was found from the theories due to counterion condensation. The effect of surface charge showed not only the repulsion of the polyion from the surface but also the shrinkage in the high ξ region due to the additional counterions required for electrical neutrality. The addition of salts led to the shrinkage of the brush heights, and in the high ξ region, additional extension was found. The computational strategy for calculating the friction dynamics of the system is also discussed.


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About this article

Structure of polyelectrolyte brushes studied by coarse grain simulations

Show Author's information Hitoshi WASHIZU1,2( ), Tomoyuki KINJO1,2, Hiroaki YOSHIDA1,2
Toyota Central R&D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan
Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, Katsura, Kyoto 615-8520, Japan

Abstract

As an example of a very low friction system, Monte Carlo Brownian dynamics simulations have been used to calculate equilibrium structures of a polyelectrolyte brush grafted onto planes. The polymers were calculated in a semi-flexible coarse-grain model that is appropriate to treat the charge density of the polyion. The effect of linear charge density on the polyion ξ, the surface negative charge, and added salts were studied. In salt-free solution, scaling theories predicted the structure well in the low ξ region. In the high ξ region, additional shrinkage was found from the theories due to counterion condensation. The effect of surface charge showed not only the repulsion of the polyion from the surface but also the shrinkage in the high ξ region due to the additional counterions required for electrical neutrality. The addition of salts led to the shrinkage of the brush heights, and in the high ξ region, additional extension was found. The computational strategy for calculating the friction dynamics of the system is also discussed.

Keywords: friction, polyelectrolyte brush, Monte Carlo Brownian dynamics simulation, soft materials, automotive tribology

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Publication history

Received: 21 September 2013
Revised: 13 February 2014
Accepted: 14 February 2014
Published: 11 March 2014
Issue date: March 2014

Copyright

© The author(s) 2014

Acknowledgements

The present work was partially supported by the MEXT program "Elements Strategy Initiative to Form Core Research Center" (since 2012), MEXT; Ministry of Education Culture, Sports, Science and Technology, Japan.

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This article is published with open access at Springerlink.com

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