Dendritic structures of poly(ethylene glycol) on silicon nitride and gold surfaces

Zhiyong Suo, Fernando Terán Arce, Recep Avci, Kate Thieltges, Brenda Spangler

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

A hydrophilic silicon nitride surface was grafted with poly(ethylene glycol) monomethyl ether (average formula weight of 5000 Da) in a one-step protocol. The domains of stable dendritic structures of self-assembled monolayer islands on a silicon nitride surface were observed with atomic force microscopy. The moduli of elasticity of these dendritic structures in air and in KCl aqueous solution were compared. The value of the Young's modulus of these structures is reduced by more than 3 orders of magnitude, from ∼12 GPa measured in air to ∼5 MPa in KCl solution. This dramatic reduction in elasticity was attributed to the swelling of the dendritic structures in aqueous solution, which was verified by the increased film thickness. These dendritic structures were not stable in the aqueous environment and could be removed by soaking in water for 22 h because of the hydrolysis of the silicate bonds. This fact was confirmed by the reduction of the C 1 s signal in the X-ray photoelectron spectroscopy experiments. These morphologies are not unique to silicon nitride substrate; similar features were also observed for thiolated poly(ethylene glycol) monomethyl ether molecules absorbed on a gold surface.

Original languageEnglish (US)
Pages (from-to)3844-3850
Number of pages7
JournalLangmuir
Volume22
Issue number8
DOIs
StatePublished - Apr 11 2006
Externally publishedYes

ASJC Scopus subject areas

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

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