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Title: The effect of multivalent counterions to the structure of highly dense polystyrene sulfonate brushes

Surface tethered polyelectrolyte brushes are scientifically interesting and technologically relevant to many applications, ranging from colloidal stabilization to responsive and tunable materials to lubrication. Many applications operate in environments containing multi-valent ions, media in which our scientific understanding is not yet well-developed. In this paper, we synthesized high-density polystyrene sulfonate (PSS) brushes via surface initiated atom-transfer radical polymerization, and performed neutron reflectivity (NR) measurements to investigate and compare the effects of mono-valent Rb + and tri-valent Y 3+ counterions to the structure of the densely tethered PSS brushes. Our NR results show that in mono-valent RbNO 3 solution, the dense PSS brush retained its full thickness up to a salt concentration of 1 M, whereas it immediately collapsed upon adding 1.67 mM of tri-valent Y 3+. Increasing the concentration of Y 3+ beyond this level did not lead to any significant further structure change of the PSS brush. Finally, our findings demonstrate that the presence of multi-valent counterions can significantly alter the structure of polyelectrolyte brushes, in a manner different from mono-valent ions, which has implications for the functionality of the brushes.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [1]
  1. Univ. of Chicago, IL (United States). Inst. for Molecular Engineering; Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
  2. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). NIST Center for Neutron Research; Univ. of Akron, OH (United States). Dept. of Polymer Engineering
  3. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). NIST Center for Neutron Research
Publication Date:
Grant/Contract Number:
AC02-06CH11357; DMR-1420709
Type:
Accepted Manuscript
Journal Name:
Polymer
Additional Journal Information:
Journal Volume: 98; Journal ID: ISSN 0032-3861
Publisher:
Elsevier
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Chicago, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Contributing Orgs:
National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Akron, OH (United States)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Polyelectrolyte; Brush; Multivalentions; ATRP; Neutron; reflectivity
OSTI Identifier:
1352673
Alternate Identifier(s):
OSTI ID: 1359786