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Reaction enthalpies of metal-polyimide interface formation observed by calorimetry Murdey, Richard
Abstract
A calorimeter has been developed to study metal-polymer interfaces in ultrahigh vacuum (UHV) conditions. Metal atoms are pulsewise deposited on a polymer substrate, gradually forming a metallic overlayer, while the reaction heat is measured in-situ with a pyroelectric sensor. Differential enthalpies of interface formation are derived from the calorimetry data and reported as a function of metal coverage. The ability of the instrument to resolve the underlying chemical reactions and growth morphology that characterize these interfacial systems is confirmed by the widely different enthalpy curves observed for each of the three metals studied in the present work - calcium, chromium and copper - deposited on PMDA-ODA polyimide substrates and the correspondingly distinct conclusions about the interfacial reactivity that were made in each case: Strong binding was discovered at the interface between calcium and polyimide. A calcium-polyimide complex with a binding energy of 600 ± 20 kJ/mol is suggested from the high initial intensity and exponential decay of the observed enthalpies with increasing metal coverage. The surface density of calcium binding sites was estimated at 4.1 nm- 2 . A more complicated reactivity was observed for the chromium-polyimide interface. Reaction enthalpies of approximately 60 ± 20 kJ/mol were observed at low coverages, six times lower than the enthalpy of formation of bulk chromium metal. This indicates the creation of a thermodynamically unstable interface. Chromium deposition apparently induces an endothermic disruption of the polyimide surface, which both lowers the net reaction enthalpy and suppresses the formation of metal-metal bonds. The copper results, meanwhile, are consistent with the formation of spherical metal clusters. The calorimeter records the change in surface energy from which the physical properties of the metal clusters, such as the cluster size, can be determined as a function of coverage.
Item Metadata
Title |
Reaction enthalpies of metal-polyimide interface formation observed by calorimetry
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2003
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Description |
A calorimeter has been developed to study metal-polymer interfaces in ultrahigh
vacuum (UHV) conditions. Metal atoms are pulsewise deposited on a
polymer substrate, gradually forming a metallic overlayer, while the reaction
heat is measured in-situ with a pyroelectric sensor. Differential enthalpies
of interface formation are derived from the calorimetry data and reported
as a function of metal coverage. The ability of the instrument to resolve
the underlying chemical reactions and growth morphology that characterize
these interfacial systems is confirmed by the widely different enthalpy curves
observed for each of the three metals studied in the present work - calcium,
chromium and copper - deposited on PMDA-ODA polyimide substrates and
the correspondingly distinct conclusions about the interfacial reactivity that
were made in each case: Strong binding was discovered at the interface between
calcium and polyimide. A calcium-polyimide complex with a binding
energy of 600 ± 20 kJ/mol is suggested from the high initial intensity and
exponential decay of the observed enthalpies with increasing metal coverage.
The surface density of calcium binding sites was estimated at 4.1 nm- 2 .
A more complicated reactivity was observed for the chromium-polyimide
interface. Reaction enthalpies of approximately 60 ± 20 kJ/mol were observed
at low coverages, six times lower than the enthalpy of formation of
bulk chromium metal. This indicates the creation of a thermodynamically
unstable interface. Chromium deposition apparently induces an endothermic
disruption of the polyimide surface, which both lowers the net reaction
enthalpy and suppresses the formation of metal-metal bonds. The copper
results, meanwhile, are consistent with the formation of spherical metal clusters.
The calorimeter records the change in surface energy from which the
physical properties of the metal clusters, such as the cluster size, can be
determined as a function of coverage.
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Extent |
3695087 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-11-17
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0061899
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2003-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.