Measurement of non-DLVO force on a silicon substrate coated with ammonium poly(acrylic acid) using scanning probe microscopy

Toshihiro Isobe, Yosuke Nakano, Yoshikazu Kameshima, Akira Nakajima, Kiyoshi Okada

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6 Citations (Scopus)


The repulsive force originating from steric hindrance of polymers in aqueous solvent was investigated using scanning probe microscopy (SPM). The contact angle (CA) of ammonium poly(acrylic acid) (PAA) solution on the Si surface was measured to estimate the state of the Si substrate. Results of CA measurement show that the Si surface was fully covered with PAA at 0.1 mass% in aqueous solution. The interaction force between the Si tip and the wafer was estimated using the SPM force curve mode. The force curve measured in the ion-exchanged purified water showed the typical relation predicted by Derjaguin-Landau-Verway-Overbeek (DLVO) theory. However, the force curve shape in the 0.1 mass% PAA solution was significantly different. Only a repulsive force was observed at less than about 4 nm of separation distance between the Si wafer and cantilever tip. This distance originated from the steric repulsions of PAA adsorbed onto the Si wafer and cantilever tip. Crown

Original languageEnglish
Pages (from-to)8710-8713
Number of pages4
JournalApplied Surface Science
Issue number20
Publication statusPublished - Jul 30 2009
Externally publishedYes



  • Atomic force microscopy
  • Coatings
  • Dispersion
  • DLVO theory
  • Force curve

ASJC Scopus subject areas

  • Surfaces, Coatings and Films

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