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The glass transition of thin polymer films in relation to the interfacial dynamics
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10.1063/1.3248368
/content/aip/journal/jcp/131/15/10.1063/1.3248368
http://aip.metastore.ingenta.com/content/aip/journal/jcp/131/15/10.1063/1.3248368
View: Figures

Figures

Image of FIG. 1.
FIG. 1.

Measurements of the dielectric loss vs frequency at different temperatures, showing the dynamic glass transition of PVAc in the bulk (upper part) and in a thin layer of 6 nm thickness (lower part).

Image of FIG. 2.
FIG. 2.

Measurements of the dielectric loss vs frequency at 330 K, showing the dynamic glass transition of PVAc in the bulk and in thin films of different thicknesses (measured in the capped geometry). In the inlet an optical image of a thin capped polymer layer is presented (the width of the electrodes is 0.75 mm).

Image of FIG. 3.
FIG. 3.

Measured mean relaxation time of the dynamic glass transition (normalized in respect to the bulk value) as a function of film thickness for several polymeric systems investigated in thin (capped) layers (PMMA, P2VP, PVAc, and HBP).

Image of FIG. 4.
FIG. 4.

Schematic representation of thin capped layers of polymers exhibiting changes in their dielectric function at solid interfaces.

Image of FIG. 5.
FIG. 5.

Calculated spectra of (a) the alpha relaxation process of a polymer in the bulk ; (b) the resulting dielectric loss in thin films, in systematic dependence on film thickness, by considering, in addition to the bulk contribution, two interfacial dead layers of 2 nm thickness with no dielectric loss .

Image of FIG. 6.
FIG. 6.

[(a) experiment] Measured dielectric loss vs frequency showing the alpha relaxation process of hexyl-imidazole at 180 K, measured in a capped geometry ( thickness) and together with a dead layer (Teflon) of comparable thickness; [(b) calculations] calculated dielectric loss for the experimental situation presented above.

Image of FIG. 7.
FIG. 7.

Calculated spectra of (a) the alpha relaxation process of a polymer in the bulk ; (b) correction function [see Eq. (5)] expressing the proportionality relation between the resulting dielectric loss of thin films and that of the polymer in the bulk.

Image of FIG. 8.
FIG. 8.

Calculated spectra of (a) relaxation processes of a polymer in the bulk and in 2 nm thick interfacial sublayers (a reduction by three orders of magnitude in the dielectric strength is assumed at the interface, , all other Havriliak–Negami parameters are identical to bulk); (b) resulting dielectric loss of thin films in systematic dependence on film thickness.

Image of FIG. 9.
FIG. 9.

Calculated spectra of (a) relaxation processes of a polymer in the bulk and in 2 nm thick interfacial sublayers (a pronounced broadening of the dynamic glass transition is assumed at the interface, , all other Havriliak–Negami parameters are identical to bulk); (b) resulting dielectric loss of thin films in systematic dependence on film thickness.

Image of FIG. 10.
FIG. 10.

Calculated spectra of (a) relaxation processes of a polymer in the bulk and in 2 nm thick interfacial sublayers (a pronounced slowing down of the dynamic glass transition is assumed at the interface, , all other Havriliak–Negami parameters are identical to bulk); (b) resulting dielectric loss of thin films in systematic dependence on film thickness.

Image of FIG. 11.
FIG. 11.

Calculated spectra of (a) the alpha relaxation process of a polymer in the bulk and the residual dielectric loss of 2 nm thick aluminum oxide layers ; (b) resulting dielectric loss of thin films in systematic dependence on film thickness.

Image of FIG. 12.
FIG. 12.

The curves shown in Fig. 11(b) are presented normalized to emphasize a broadening of the dynamic glass transition under the considered conditions.

Image of FIG. 13.
FIG. 13.

Calculated spectra of (a) relaxation processes of a polymer in the bulk and in 2 nm thick interfacial sublayers, where a pronounced slowing down and broadening of the dynamic glass transition together with suppression of relaxation modes are assumed [, , , all other Havriliak–Negami parameters are identical to bulk] in addition to 2 nm thick oxide layers with ; (b) resulting dielectric loss of thin films in systematic dependence on film thickness.

Image of FIG. 14.
FIG. 14.

Calculated spectra of (a) relaxation processes of a polymer in the bulk and in the interfacial sublayers (a pronounced slowing down and broadening of the dynamic glass transition together with suppression of relaxation modes are assumed at the interface, , , , all other Havriliak–Negami parameters are identical to bulk); (b) resulting dielectric loss in a thin film of 12 nm thickness for different thicknesses of the interfacial sublayers.

Image of FIG. 15.
FIG. 15.

Calculated spectra of (a) the alpha relaxation process of a polymer in the bulk for different values of the dielectric strength [2 nm thick interfacial layers with , , and are considered as well]; (b) resulting dielectric loss in a thin film of 8 nm thickness for the considered dielectric strengths.

Image of FIG. 16.
FIG. 16.

Calculated relaxation time of the dynamic glass transition (normalized in respect to the bulk value) in thin films of polymers having different dielectric strengths in dependence on film thickness (2 nm thick interfacial layers with a dielectric function described in Fig. 15(a) are considered as well).

Image of FIG. 17.
FIG. 17.

Measured alpha relaxation process for PMMA, P2VP, PVAc, and HBP in the bulk.

Image of FIG. 18.
FIG. 18.

[(a) experiment] Measured dielectric loss vs temperature at 300 Hz showing the alpha relaxation process of PVAc in thin (capped) layers of different thicknesses; [(b) calculations] calculated dielectric loss vs temperature at 300 Hz showing the alpha relaxation process of PVAc in thin (capped) layers of different thicknesses [2 nm thick interfacial layers with are assumed].

Image of FIG. 19.
FIG. 19.

[(a) experiment] Measured dielectric loss vs temperature at 96 Hz showing the alpha relaxation process of HBP in thin (capped) layers of different thicknesses; [(b) calculations] calculated dielectric loss vs temperature at 96 Hz showing the alpha relaxation process of HBP in thin (capped) layers of different thicknesses [3 nm thick interfacial layers with are assumed].

Image of FIG. 20.
FIG. 20.

Calculated of HBP vs temperature at 1.2 MHz in thin (capped) layers of different thicknesses by considering 3 nm thick interfacial layers with .

Image of FIG. 21.
FIG. 21.

Temperature position of the alpha relaxation peak (taken from the “net” dielectric loss of thin films) of HBP at 96 Hz and dilatometric glass transition temperature (extracted as defined by Fig. 20) in dependence on film thickness.

Image of FIG. 22.
FIG. 22.

Schematic representation of thin polymer films measured in an air-gap geometry.

Image of FIG. 23.
FIG. 23.

(a) Recently developed experimental approach enables one dielectric measurement on ultrathin polymer films in an air-gap geometry; (b) matrix of silica nanostructures employed as spacers; (c) geometrical profile of the nanospacers as measured by atomic force microscopy.

Image of FIG. 24.
FIG. 24.

Calculated dielectric loss vs frequency showing the alpha relaxation process of thin polymer films measured in an air-gap geometry in systematic dependence on the film thickness and on the dielectric strength of the polymer in the bulk .

Image of FIG. 25.
FIG. 25.

Calculated dielectric loss vs frequency showing the alpha relaxation process in thin polymer films as measured in an air-gap geometry (a 4 nm thick dead layer with no dielectric loss at the interface with the solid electrode is considered).

Image of FIG. 26.
FIG. 26.

Calculated dielectric loss vs frequency showing the alpha relaxation process in thin polymer films as measured in an air-gap geometry (a 4 nm thick dead layer with reduced dielectric loss at the interface with the solid electrode is considered).

Image of FIG. 27.
FIG. 27.

Calculated dielectric loss vs frequency showing the alpha relaxation process in thin polymer films as measured in an air-gap geometry [a broadening of the dynamic glass transition in a 4 nm thick interfacial layer is considered, ].

Image of FIG. 28.
FIG. 28.

Calculated dielectric loss vs frequency showing the alpha relaxation process in thin polymer films as measured in an air-gap geometry (a slowing down of the dynamic glass transition in a 4 nm thick interfacial layer is considered).

Image of FIG. 29.
FIG. 29.

Calculated dielectric loss vs frequency showing the alpha relaxation process in thin polymer films as measured in an air-gap geometry in systematic dependence on the dielectric strength of the polymer in the bulk [a 4 nm thick oxide layer is considered as well with ].

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/content/aip/journal/jcp/131/15/10.1063/1.3248368
2009-10-19
2014-04-21
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: The glass transition of thin polymer films in relation to the interfacial dynamics
http://aip.metastore.ingenta.com/content/aip/journal/jcp/131/15/10.1063/1.3248368
10.1063/1.3248368
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