Langmuir study of octadecyltrimethoxysilane behavior at the air-water interface

S. Vidon, Roger Leblanc

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The behavior of octadecyltrimethoxysilane (C18TMS) at the air-water interface for different subphases pH has been studied through surface pressure-area and surface potential-area isotherms combined with Brewster angle microscopy. C18TMS monomolecular behavior has been assigned to the one observed at pH around 8.0. Hydrolysis or hydrolysis followed by condensation occurs when pH is lowered below 5.0. Hydrolysis followed by condensation is also observed when the pH is raised above 10.5. The type of catalysis predominantly influences the product of the reaction. Condensation is performed at low pH under two constraints: steric hindrance between the C18 tail chains and electrostatic repulsion between polar groups, resulting in a very low or nil polymerization degree of the condensation products around the isoelectric point (pH 3.8). Higher concentration of chloride ions gradually inhibits the second constraint, resulting in the formation of a linear polymer. Only steric hindrance has been observed under basic catalysis, producing a monodimensional polymer similar to the one obtained at low pH.

Original languageEnglish
Pages (from-to)1279-1286
Number of pages8
JournalJournal of Physical Chemistry B
Volume102
Issue number7
StatePublished - Feb 12 1998

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Condensation
Hydrolysis
Water
air
Air
water
Catalysis
condensation
Polymers
hydrolysis
Surface potential
catalysis
Isotherms
Chlorides
Electrostatics
Microscopic examination
Polymerization
Ions
Brewster angle
polymers

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Engineering(all)

Cite this

Langmuir study of octadecyltrimethoxysilane behavior at the air-water interface. / Vidon, S.; Leblanc, Roger.

In: Journal of Physical Chemistry B, Vol. 102, No. 7, 12.02.1998, p. 1279-1286.

Research output: Contribution to journalArticle

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