Effect of headgroup dissociation on the structure of Langmuir monolayers

A. Datta*, J. Kmetko, A. G. Richter, C. J. Yu, Pulak Dutta, K. S. Chung, J. M. Bai

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Scopus citations


We present results of grazing incidence X-ray diffraction studies concerning the effect of pH (and thus, of headgroup dissociation) on Langmuir monolayers of fatty acids, in the absence of any divalent cations in the aqueous subphase. An increase in pH transforms the distorted-hexagonal S phase first to the partially disordered Rotator-I phase with less distortion, and then to the completely disordered Rotator-II phase with an undistorted hexagonal structure. The S-Rotator-I and Rotator-I-Rotator-II transitions are pushed to lower temperatures with increase in pH. The fact that the effects of pH increase are almost identical to the effects of increasing temperature indicates the important role of headgroup-headgroup interactions in these monolayer phases.

Original languageEnglish (US)
Pages (from-to)1239-1242
Number of pages4
Issue number3
StatePublished - Feb 8 2000

ASJC Scopus subject areas

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

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