Molecular ordering in thin liquid films of polydimethylsiloxanes

G. Evmenenko*, S. W. Dugan, J. Kmetko, P. Dutta

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

X-ray reflectivity has been used for investigations of molecular-ordering in thin liquid films of polydimethylsiloxanes (PDMS) of low molecular weights deposited on a polished silicon wafer. The liquid films we studied were ∼40-90 Å thick. Evidence of molecular layering induced by geometrical confinement by a hard wall is obtained for thin films of lowest molecular weight PDMS. The positions of the secondary maxima in the Patterson functions, P(z), for these samples reveal a periodicity of about 10 Å, consistent with the size of PDMS molecules. Further increasing the molecular weight leads to suppression of P(z) oscillations, causing the electron density profile to become more uniform. For higher molecular weight PDMS, a flatlike conformation of molecules absorbed on a solid surface is observed.

Original languageEnglish (US)
Pages (from-to)4021-4024
Number of pages4
JournalLangmuir
Volume17
Issue number13
DOIs
StatePublished - Jun 26 2001

ASJC Scopus subject areas

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

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