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This content will become publicly available on June 29, 2019

Title: Multivalent counterions diminish the lubricity of polyelectrolyte brushes

Polyelectrolyte brushes provide wear protection and lubrication in many technical, medical, physiological, and biological applications. Wear resistance and low friction are attributed to counterion osmotic pressure and the hydration layer surrounding the charged polymer segments. However, the presence of multivalent counterions in solution can strongly affect the interchain interactions and structural properties of brush layers. We evaluated the lubrication properties of polystyrene sulfonate brush layers sliding against each other in aqueous solutions containing increasing concentrations of counterions. The presence of multivalent ions (Y 3+, Ca 2+, Ba 2+), even at minute concentrations, markedly increases the friction forces between brush layers owing to electrostatic bridging and brush collapse. Furthermore, our results suggest that the lubricating properties of polyelectrolyte brushes in multivalent solution are hindered relative to those in monovalent solution.
Authors:
ORCiD logo [1] ; ORCiD logo [2] ;  [3] ;  [4] ;  [4] ; ORCiD logo [3] ;  [2] ; ORCiD logo [2]
  1. Univ. of Chicago, Chicago, IL (United States); Argonne National Lab. (ANL), Lemont, IL (United States); Nanyang Technological Univ. (Singapore)
  2. Univ. of Chicago, Chicago, IL (United States); Argonne National Lab. (ANL), Lemont, IL (United States)
  3. Univ. of Massachusetts, Lowell, MA (United States)
  4. Ben-Gurion Univ. of the Negev, Midreshet Ben-Gurion (Israel)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Science
Additional Journal Information:
Journal Volume: 360; Journal Issue: 6396; Journal ID: ISSN 0036-8075
Publisher:
AAAS
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION
OSTI Identifier:
1463685