The effect of humidity on the stability of an octadecyltriethoxysilane monolayer self-assembled on untreated and plasma-treated mica

Sungsoo Kim, Hugo K. Christenson, Joan E Curry

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

We investigated the stability of an octadecyltriethoxysilane (OTE) monolayer self-assembled on plasmatreated and untreated mica using a surface forces apparatus by measuring the thickness of the water layer that is adsorbed from vapor. The OTE monolayers are initially highly hydrophobic, but contact angle hysteresis indicates that water interacts favorably with the monolayers on prolonged exposure. Defects in the monolayer most likely make it possible for the water to reach the hydrophilic region between the silane headgroups and the mica. This explains why there has been very little success in measuring hydrophobic forces between OTE-coated mica surfaces. Hydrophobic forces between OTE surfaces have been successfully measured only with silica as the substrate. Even though these monolayers are not suitable for studies of the so-called hydrophobic force, they are ideal for studies designed to probe the interactions between the silane headgroups and mica. For a given relative humidity, the water film thickness is always less if the surfaces are plasma-treated before the monolayer is deposited. In the untreated case, water penetrates into the hydrophilic region between the monolayer and the mica. This does not occur in the plasma-treated case because the monolayer is more firmly anchored, most likely through covalent bonding.

Original languageEnglish (US)
Pages (from-to)2125-2129
Number of pages5
JournalLangmuir
Volume18
Issue number6
DOIs
StatePublished - Mar 19 2002

Fingerprint

Mica
Self assembled monolayers
mica
humidity
Monolayers
Atmospheric humidity
Plasmas
water
Water
silanes
Silanes
film thickness
hysteresis
vapors
silicon dioxide
Silicon Dioxide
Contact angle
Film thickness
Hysteresis
probes

ASJC Scopus subject areas

  • Colloid and Surface Chemistry
  • Physical and Theoretical Chemistry

Cite this

The effect of humidity on the stability of an octadecyltriethoxysilane monolayer self-assembled on untreated and plasma-treated mica. / Kim, Sungsoo; Christenson, Hugo K.; Curry, Joan E.

In: Langmuir, Vol. 18, No. 6, 19.03.2002, p. 2125-2129.

Research output: Contribution to journalArticle

@article{9e6d003997474b68b78bc32f85666c56,
title = "The effect of humidity on the stability of an octadecyltriethoxysilane monolayer self-assembled on untreated and plasma-treated mica",
abstract = "We investigated the stability of an octadecyltriethoxysilane (OTE) monolayer self-assembled on plasmatreated and untreated mica using a surface forces apparatus by measuring the thickness of the water layer that is adsorbed from vapor. The OTE monolayers are initially highly hydrophobic, but contact angle hysteresis indicates that water interacts favorably with the monolayers on prolonged exposure. Defects in the monolayer most likely make it possible for the water to reach the hydrophilic region between the silane headgroups and the mica. This explains why there has been very little success in measuring hydrophobic forces between OTE-coated mica surfaces. Hydrophobic forces between OTE surfaces have been successfully measured only with silica as the substrate. Even though these monolayers are not suitable for studies of the so-called hydrophobic force, they are ideal for studies designed to probe the interactions between the silane headgroups and mica. For a given relative humidity, the water film thickness is always less if the surfaces are plasma-treated before the monolayer is deposited. In the untreated case, water penetrates into the hydrophilic region between the monolayer and the mica. This does not occur in the plasma-treated case because the monolayer is more firmly anchored, most likely through covalent bonding.",
author = "Sungsoo Kim and Christenson, {Hugo K.} and Curry, {Joan E}",
year = "2002",
month = "3",
day = "19",
doi = "10.1021/la011020x",
language = "English (US)",
volume = "18",
pages = "2125--2129",
journal = "Langmuir",
issn = "0743-7463",
publisher = "American Chemical Society",
number = "6",

}

TY - JOUR

T1 - The effect of humidity on the stability of an octadecyltriethoxysilane monolayer self-assembled on untreated and plasma-treated mica

AU - Kim, Sungsoo

AU - Christenson, Hugo K.

AU - Curry, Joan E

PY - 2002/3/19

Y1 - 2002/3/19

N2 - We investigated the stability of an octadecyltriethoxysilane (OTE) monolayer self-assembled on plasmatreated and untreated mica using a surface forces apparatus by measuring the thickness of the water layer that is adsorbed from vapor. The OTE monolayers are initially highly hydrophobic, but contact angle hysteresis indicates that water interacts favorably with the monolayers on prolonged exposure. Defects in the monolayer most likely make it possible for the water to reach the hydrophilic region between the silane headgroups and the mica. This explains why there has been very little success in measuring hydrophobic forces between OTE-coated mica surfaces. Hydrophobic forces between OTE surfaces have been successfully measured only with silica as the substrate. Even though these monolayers are not suitable for studies of the so-called hydrophobic force, they are ideal for studies designed to probe the interactions between the silane headgroups and mica. For a given relative humidity, the water film thickness is always less if the surfaces are plasma-treated before the monolayer is deposited. In the untreated case, water penetrates into the hydrophilic region between the monolayer and the mica. This does not occur in the plasma-treated case because the monolayer is more firmly anchored, most likely through covalent bonding.

AB - We investigated the stability of an octadecyltriethoxysilane (OTE) monolayer self-assembled on plasmatreated and untreated mica using a surface forces apparatus by measuring the thickness of the water layer that is adsorbed from vapor. The OTE monolayers are initially highly hydrophobic, but contact angle hysteresis indicates that water interacts favorably with the monolayers on prolonged exposure. Defects in the monolayer most likely make it possible for the water to reach the hydrophilic region between the silane headgroups and the mica. This explains why there has been very little success in measuring hydrophobic forces between OTE-coated mica surfaces. Hydrophobic forces between OTE surfaces have been successfully measured only with silica as the substrate. Even though these monolayers are not suitable for studies of the so-called hydrophobic force, they are ideal for studies designed to probe the interactions between the silane headgroups and mica. For a given relative humidity, the water film thickness is always less if the surfaces are plasma-treated before the monolayer is deposited. In the untreated case, water penetrates into the hydrophilic region between the monolayer and the mica. This does not occur in the plasma-treated case because the monolayer is more firmly anchored, most likely through covalent bonding.

UR - http://www.scopus.com/inward/record.url?scp=0037133830&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0037133830&partnerID=8YFLogxK

U2 - 10.1021/la011020x

DO - 10.1021/la011020x

M3 - Article

AN - SCOPUS:0037133830

VL - 18

SP - 2125

EP - 2129

JO - Langmuir

JF - Langmuir

SN - 0743-7463

IS - 6

ER -