Surface stress, thickness, and mass of the first few layers of polyelectrolyte

Masaya Toda, Akiko N. Itakura, Shinichi Igarashi, Karsten Büscher, Jochen S. Gutmann, Karlheinz Graf, Rüdiger Berger

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

The effects of surface stress and mass loading upon the adsorption of polyelectrolytes onto flexible silicon micromechanical cantilever sensors (MCSs) were studied in situ. A self-assembled monolayer of 2-mercaptoethylamine chloride (2-MEA) on gold was used to achieve single-side adsorption on the MCS. Such a preparation gave a positive surface potential, whereas a bare SiO x surface gave a negative surface potential. Wide scan X-ray photoelectron spectroscopy confirmed that the adsorption of polystyrenesulfonate (PSS) and polyallylamine hydrochloride (PAH) followed the general rule expected from the electrostatic interaction between the substrate and the polyelectrolyte, whereas the adsorption polyethyleneimine (PEI) did not. The adsorption of PAH on SiOx from a 3 mM water solution containing 1 M NaCl was associated with a deflection of the MCS toward the polyelectrolyte monolayer (tensile surface stress) owing to the hydrogen bonding between neighboring amino groups. Here, a surface stress change of 1.4 ±0.1 N/m was estimated. The adsorption of PSS from a 3 mM water solution containing 1 M NaCl on a 2-MEA surface induced a deflection of the MCS away from the polyelectrolyte layer (compressive stress), toward the SiOx side. Here, a surface stress change of 3.1 ±0.3 N/m was determined. The formation of a PAH layer on top of the PSS layer resulted in a deflection of the MCS toward the PAH layer. This indicated that the adjacent PSS layer was deswelling, corresponding to a surface stress change of 0.5 ±0.1 N/m.

Original languageEnglish
Pages (from-to)3191-3198
Number of pages8
JournalLangmuir
Volume24
Issue number7
DOIs
Publication statusPublished - 2008 Apr 1
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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    Toda, M., Itakura, A. N., Igarashi, S., Büscher, K., Gutmann, J. S., Graf, K., & Berger, R. (2008). Surface stress, thickness, and mass of the first few layers of polyelectrolyte. Langmuir, 24(7), 3191-3198. https://doi.org/10.1021/la7028214