Hydration in weak polyelectrolyte brushes

Chaitra Deodhar, Erick Soto-Cantu, David Uhrig, Peter Bonnesen, Bradley S. Lokitz, John F. Ankner, S. Michael Kilbey

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Weak polyelectrolytes (PEs) are complex because intertwined connections between conformation and charge are regulated by the local dielectric environment. While end-tethered PE chains - so-called PE "brushes" - are archetypal systems for comprehending structure-property relationships, it is revealed that the reference state nominally referred to as "dry" is, in fact, a situation in which the chains are hydrated by water vapor in the ambient. Using charge-negative PE homopolymer brushes based on methacrylic acid and copolymer brushes that incorporate methacrylic acid and 2- hydroxyethylmethacrylate, we determine self-consistently the water content of PE films using neutron reflectometry under different hydration conditions. Modeling multiple data sets, we obtain dry polymer mass density and layer thickness, independent of adsorbed water, and PE brush profiles into different pH solutions. We show that hydration of the chains distorts, here by as much as 30%, the quantification of these important physical parameters benchmarked to films in ambient conditions.

Original languageEnglish
Pages (from-to)398-402
Number of pages5
JournalACS Macro Letters
Volume2
Issue number5
DOIs
StatePublished - May 21 2013

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