Ionizable polyelectrolyte brushes: brush height and electrosteric interaction

P.M. Biesheuvel

    Research output: Contribution to journalArticleAcademicpeer-review

    56 Citations (Scopus)

    Abstract

    Semi-analytical scaling theory is used to describe quenched and annealed (weakly charged, ionizable, charge-regulating) polyelectrolyte brushes in electrolyte solutions of arbitrary salt concentration. An Alexander-De Gennes box model with homogeneous distribution of polymer segments and the free ends located at the edge of the brush is assumed, as is local electroneutrality in the brush. For annealed polyelectrolyte and in the low-salt regime, the theory predicts that for sufficiently dense brushes, the salt concentration has a small influence on brush height, while the brush expands with increasing grafting density, in agreement with experiment. Expressions are presented for the interaction free energy of compressed ionizable and quenched polyelectrolyte brushes (proportional to the force between particles or curved surfaces). In all cases, the required prefactors are explicitly stated. The theory is compared directly with published experiments on the influence of salt concentration, pH, and grafting density on the thickness and interaction force of polystyrene sulfonate (quenched) and poly(meth)acrylic acid (annealed) brushes. In general, trends are well reproduced but significant deviations remain.
    Original languageEnglish
    Pages (from-to)97-106
    JournalJournal of Colloid and Interface Science
    Volume275
    Issue number1
    DOIs
    Publication statusPublished - 2004

    Keywords

    • polymer brushes
    • scaling relations
    • surface forces
    • field theory
    • layers
    • model
    • electrolyte
    • simulations
    • copolymers
    • adsorption

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