Structure of Polyelectrolyte Brushes in the Presence of Multivalent Counterions

Published

August 9, 2016

Author(s)

Jing Yu, Jun Mao, Guangcui Yuan, Sushil K. Satija, Zhang Jiang, Wei Chen, Matthew Tirrell

Abstract

Polyelectrolyte brushes are of great importance to a wide range of fields, ranging from colloidal stabilization to responsive and tunable materials to lubrication. We synthesized high-density polystyrene sulfonate (PSS) brushes using surface force measurements using a surface forces apparatus (SFA) to investigate the effect of monovalent Na⁺, divalent Ca²⁺, Mg²⁺, and Ba²⁺, and trivalent Y³⁺ counterions, to the structure of PSS brushes. NR and SFA results demonstrate that in monovalent salt solution, the behavior PSS brush agrees with scaling theory well, exhibiting two distinct regimes, the osmotic and salted/} brush regimes. Introducing trivalent Y³⁺ cations causes an abrupt shrinkage of the PSS brush due to the uptake of Y³⁺ counterions. The update of Y³⁺ counterions and shrinkage of the brush are reversible up on increasing the concentration of monovalent salt. Divalent cations, Mg²⁺, Ca²⁺, and Ba⁺, while all significantly affecting the structure of PSS brushes, show strong ion specific effects that are related to the specific interactions between the divalent cations and the sulfonate groups. Our results demonstrate that the presence of multivalent counterions, even at relatively low concentrations, can strongly affect the structure of polyelectrolyte brushes. The results also highlight the importance of ion specificity to the structure of polyelectrolyte brushes in solution.

Citation

Macromolecules

Volume

49

Issue

15

Pub Type

Journals

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Keywords

polyelectrolyte, brushe, multivalent counterion

Citation

Yu, J. , Mao, J. , Yuan, G. , Satija, S. , Jiang, Z. , Chen, W. and Tirrell, M. (2016), Structure of Polyelectrolyte Brushes in the Presence of Multivalent Counterions, Macromolecules, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=921042 (Accessed April 25, 2024)