Surface forces apparatus (SFA) studies on n-octadecyltriethoxysilane self-assembled monolayers on untreated and plasma-treated mica

Persistent Link:
http://hdl.handle.net/10150/289739
Title:
Surface forces apparatus (SFA) studies on n-octadecyltriethoxysilane self-assembled monolayers on untreated and plasma-treated mica
Author:
Kim, Sung-Soo
Issue Date:
2001
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Prehydrolyzed n-octadecyltriethoxysilane (OTE) molecules were self-assembled as a monolayer on both untreated and argon/water vapor plasma-treated mica. The properties and stability of these monolayers have been qualitatively and quantitatively investigated with a surface forces apparatus (SFA) under various environmental conditions The interaction force between the OTE monolayers immersed in water showed that plasma treatment reduced the range of the steep short-range repulsion and motivated the water vapor studies. The humidity tests revealed a substantial monolayer swelling in the untreated case at 95% RH or higher but there was no swelling in the plasma treated case. Furthermore, adhesive force measurements as a function of variations in environmental conditions such as temperature, relative humidity, contact time, and high stress showed that the plasma treated OTE monolayer appears to be more stable than the untreated monolayer in high humidities. In dry conditions both rnonolayers are molecularly smooth, well ordered and highly compact as well as mechanically robust and tenacious. Finally, the thickness compressibility studies in both dry and humid conditions suggested that the OTE phase state for both the plasma treated and untreated cases is pseudo-crystalline. Further, these studies suggested that the monolayer on both plasma treated and untreated mica does not fully cover the entire surface and likely exists as two very discrete phase states composed of large crystalline polymerized OTE domains and somewhat hydrophilic gaseous regions. The results from several different SFA experiments strongly indicates the OTE-SAM is covalently attached at least partially to the plasma treated mica while the monolayer weakly physisorbs to the untreated mica surface. Accordingly, due to the covalent connection, the OTE-SAM on plasma treated mica is more stable particularly in highly humid or even completely wet environments although it is thought the monolayer does not fully cover the mica surface.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Chemistry, Physical.; Physics, Molecular.; Environmental Sciences.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Soil, Water and Environmental science
Degree Grantor:
University of Arizona
Advisor:
Curry, Joan E.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleSurface forces apparatus (SFA) studies on n-octadecyltriethoxysilane self-assembled monolayers on untreated and plasma-treated micaen_US
dc.creatorKim, Sung-Sooen_US
dc.contributor.authorKim, Sung-Sooen_US
dc.date.issued2001en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractPrehydrolyzed n-octadecyltriethoxysilane (OTE) molecules were self-assembled as a monolayer on both untreated and argon/water vapor plasma-treated mica. The properties and stability of these monolayers have been qualitatively and quantitatively investigated with a surface forces apparatus (SFA) under various environmental conditions The interaction force between the OTE monolayers immersed in water showed that plasma treatment reduced the range of the steep short-range repulsion and motivated the water vapor studies. The humidity tests revealed a substantial monolayer swelling in the untreated case at 95% RH or higher but there was no swelling in the plasma treated case. Furthermore, adhesive force measurements as a function of variations in environmental conditions such as temperature, relative humidity, contact time, and high stress showed that the plasma treated OTE monolayer appears to be more stable than the untreated monolayer in high humidities. In dry conditions both rnonolayers are molecularly smooth, well ordered and highly compact as well as mechanically robust and tenacious. Finally, the thickness compressibility studies in both dry and humid conditions suggested that the OTE phase state for both the plasma treated and untreated cases is pseudo-crystalline. Further, these studies suggested that the monolayer on both plasma treated and untreated mica does not fully cover the entire surface and likely exists as two very discrete phase states composed of large crystalline polymerized OTE domains and somewhat hydrophilic gaseous regions. The results from several different SFA experiments strongly indicates the OTE-SAM is covalently attached at least partially to the plasma treated mica while the monolayer weakly physisorbs to the untreated mica surface. Accordingly, due to the covalent connection, the OTE-SAM on plasma treated mica is more stable particularly in highly humid or even completely wet environments although it is thought the monolayer does not fully cover the mica surface.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectChemistry, Physical.en_US
dc.subjectPhysics, Molecular.en_US
dc.subjectEnvironmental Sciences.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineSoil, Water and Environmental scienceen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorCurry, Joan E.en_US
dc.identifier.proquest3031397en_US
dc.identifier.bibrecord.b42287418en_US
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