Water mobility: A bridge between the hofmeister series of ions and the friction of zwitterionic surfaces in aqueous environments

Yi He, Qing Shao, Shengfu Chen, Shaoyi Jiang

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

In this work, we systematically studied the effects of monovalent ions in the Hofmeister series on the friction of zwitterionic surfaces with carboxybetaine self-assembled monolayers (CB-SAMs) as model surfaces using molecular dynamics simulations. The friction coefficients between two CB-SAM surfaces under shear were calculated in the presence of LiCl, NaCl, KCl, CsCl, CsF, CsBr, or CsI solutions at 1 M. Results show that there is a strong correlation between the order of ions in the Hofmeister series and the friction of the CB-SAM surfaces. For salt solutions with the same anion, the friction of the surfaces in a solution with kosmotropic cations has larger friction than that in a solution with chaotropic ones. The same relationship between the order of ions in the Hofmeister series and the friction of the surfaces can be found for the salt solutions with the same cation but different anions. The analysis of water near the surfaces further suggests that these surfaces are hydrated with a similar amount of water molecules and the mobility of interfacial water is the key factor that bridges the relationship between the order of ions in the Hofmeister series and the friction of zwitterionic surfaces. High water mobility promotes the lubrication of zwitterionic surfaces.

Original languageEnglish
Pages (from-to)15525-15531
Number of pages7
JournalJournal of Physical Chemistry C
Volume115
Issue number31
DOIs
StatePublished - Aug 11 2011

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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