Forces between xylan-coated surfaces: Effect of polymer charge density and background electrolyte

Monika Österberg, Janne Laine, Per Stenius, Atte Kumpulainen, Per M. Claesson

Research output: Contribution to journalArticleScientificpeer-review

Abstract

The forces between xylan-coated mica surfaces at pH 10 have been studied using the interferometric surface force apparatus. Xylan is a polysaccharide that is composed of (1,4)-linked beta -D-xylopyranose units, which are partially substituted at C2 with 4-O-methyl-alpha -D-glucuronic acid units and at C3 with alpha -L-arabinosyl units. Two different xylans were studied, one with 0.5% and one with 9% of the segments containing a carboxylic acid group. It was found that both xylans adsorbed onto the negatively charged mica surface despite their negative charge. The interactions between the xylan-coated surfaces were dependent on the charge density of the polymer. The xylan with higher charge density adsorbed in a more extended conformation leading to more long-range repulsion. The shapes of the force curves were consistent with the forces expected for anchored polyelectrolyte brushes. After compression the length of the protruding chains decreased. An increase in background electrolyte concentration led to a decrease in the range of the repulsion. This effect was, as expected, more pronounced for the high charge density xylan. In the presence of CaCl2 not only the long-range forces but also the layer thickness at high compressive load decreased. (C) 2001 Academic Press.

Original languageEnglish
Pages (from-to)59-66
Number of pages8
JournalJournal of Colloid and Interface Science
Volume242
Issue number1
DOIs
Publication statusPublished - 1 Oct 2001
MoE publication typeA1 Journal article-refereed

Keywords

  • xylan
  • surface forces
  • polyelectrolyte brushes
  • adsorption
  • hemicellulose
  • CONSISTENT-FIELD THEORY
  • POLYELECTROLYTE BRUSHES
  • CELLULOSIC MATERIALS
  • MICA SURFACES
  • STABILIZATION
  • ADSORPTION
  • FIBER
  • LAYER
  • PULPS
  • ACID

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