Effects of ionic side groups attached to polydimethylsiloxanes on lubrication of silicon oxide surfaces

Erik Hsiao, Don Kim, Seong Kim

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The boundary film formation and lubrication effects of low molecular weight silicone lubricant molecules with cationic side groups were studied. Poly(N, N, N-trimethylamine-3-propylmethylsiloxane-co-dimethylsiloxane) iodide was synthesized and deposited on silicon oxide surfaces to form a bound-and-mobile lubricant film. The bound nature was investigated with ellipsometry, water contact angle, and X-ray photoelectron spectroscopy for the polymers with cationic mole percent of 6, 15, and 30 mol % (monomer based). The bound layer thickness decreased as the cationic content increased. The quaternary ammonium cations in this layer were electrostatically bound to the substrate surface. The mobile nature of the multilayers was explored with scanning polarization force microscopy. The multilayer films exhibited characteristic topographic features due to ionic interactions within the polymer film. Contact scratching of these films altered the multilayer topography within the contact scanned area. Even after high load contact scanning, the bound layer was not removed from the scanned region. These results implied that the molecules in the first layer are strongly bound and the molecules in the multilayers are mobile. Both nanoscale and macroscale tribological tests of these films revealed that the polymer with 15 mol % cationic groups gives lower friction and adhesion than the 6 and 30 mol % cationic polymers as well as the polydimethylsiloxane control sample. This seems to be due to a synergistic effect between the bound and the mobile layers.

Original languageEnglish (US)
Pages (from-to)9814-9823
Number of pages10
JournalLangmuir
Volume25
Issue number17
DOIs
StatePublished - Sep 1 2009

Fingerprint

Dimethylpolysiloxanes
Silicon oxides
Polydimethylsiloxane
lubrication
silicon oxides
Lubrication
Polymers
Multilayers
Molecules
Lubricants
polymers
lubricants
Scanning
Multilayer films
Ellipsometry
Iodides
Silicones
Ammonium Compounds
Polymer films
contact loads

All Science Journal Classification (ASJC) codes

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

Cite this

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abstract = "The boundary film formation and lubrication effects of low molecular weight silicone lubricant molecules with cationic side groups were studied. Poly(N, N, N-trimethylamine-3-propylmethylsiloxane-co-dimethylsiloxane) iodide was synthesized and deposited on silicon oxide surfaces to form a bound-and-mobile lubricant film. The bound nature was investigated with ellipsometry, water contact angle, and X-ray photoelectron spectroscopy for the polymers with cationic mole percent of 6, 15, and 30 mol {\%} (monomer based). The bound layer thickness decreased as the cationic content increased. The quaternary ammonium cations in this layer were electrostatically bound to the substrate surface. The mobile nature of the multilayers was explored with scanning polarization force microscopy. The multilayer films exhibited characteristic topographic features due to ionic interactions within the polymer film. Contact scratching of these films altered the multilayer topography within the contact scanned area. Even after high load contact scanning, the bound layer was not removed from the scanned region. These results implied that the molecules in the first layer are strongly bound and the molecules in the multilayers are mobile. Both nanoscale and macroscale tribological tests of these films revealed that the polymer with 15 mol {\%} cationic groups gives lower friction and adhesion than the 6 and 30 mol {\%} cationic polymers as well as the polydimethylsiloxane control sample. This seems to be due to a synergistic effect between the bound and the mobile layers.",
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Effects of ionic side groups attached to polydimethylsiloxanes on lubrication of silicon oxide surfaces. / Hsiao, Erik; Kim, Don; Kim, Seong.

In: Langmuir, Vol. 25, No. 17, 01.09.2009, p. 9814-9823.

Research output: Contribution to journalArticle

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