TY - JOUR
T1 - Multivalent counterions diminish the lubricity of polyelectrolyte brushes
AU - Yu, J.
AU - Jackson, N. E.
AU - Xu, X.
AU - Morgenstern, Y.
AU - Kaufman, Y.
AU - Ruths, M.
AU - de Pablo, J. J.
AU - Tirrell, M.
N1 - Funding Information:
We thank J. Mao and D. Mastropietro for assistance with the SFA experiments. J.Y., J.J.dP., and M.T. thank the U.S. Department of Energy, Office of Science, Program in Basic Energy Sciences, Materials Sciences and Engineering Division, for financial support of this work. J.Y. thanks a start-up grant of NTU, M4082049.070. N.E.J. thanks the Argonne National Laboratory Maria Goeppert Mayer Named Fellowship for support. X.X. and M.R. thank the National Science Foundation [grant nos. NSF CMMI-1562876 (X.X.) and NSF CMMI-1161475 (M.R.)], which supported the AFM experiments. Y.M. and Y.K. were supported by the Adelis Foundation. We gratefully acknowledge the computing resources provided on Blues, a high-performance computing cluster operated by the Laboratory Computing Resource Center at Argonne National Laboratory.
Publisher Copyright:
© 2017 The Authors.
PY - 2018/6/29
Y1 - 2018/6/29
N2 - 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 (Y3+, Ca2+, Ba2+), even at minute concentrations, markedly increases the friction forces between brush layers owing to electrostatic bridging and brush collapse. Our results suggest that the lubricating properties of polyelectrolyte brushes in multivalent solution are hindered relative to those in monovalent solution.
AB - 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 (Y3+, Ca2+, Ba2+), even at minute concentrations, markedly increases the friction forces between brush layers owing to electrostatic bridging and brush collapse. Our results suggest that the lubricating properties of polyelectrolyte brushes in multivalent solution are hindered relative to those in monovalent solution.
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U2 - 10.1126/science.aar5877
DO - 10.1126/science.aar5877
M3 - Article
C2 - 29954973
AN - SCOPUS:85049149820
SN - 0036-8075
VL - 360
SP - 1434
EP - 1438
JO - Science
JF - Science
IS - 6396
ER -