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Density functional approach for modeling CO2 pressurized polymer thin films in equilibrium.
Manish Talreja1, Isamu Kusaka, David L Tomasko
1William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, 140 West 19th Avenue, Columbus, Ohio 43210, USA.
The Journal of Chemical Physics
|March 5, 2009
Summary
Polymer density functional theory reveals how carbon dioxide (CO(2)) affects polymer thin film properties. CO(2) presence and film thickness alter surface tension and interface width, with end-segment segregation observed.
Area of Science:
- Materials Science
- Physical Chemistry
- Computational Physics
Background:
- Polymer thin films are crucial in various applications.
- Understanding their interfacial properties with gases like carbon dioxide (CO(2)) is essential.
- CO(2) interactions can significantly alter polymer film behavior.
Purpose of the Study:
- To analyze equilibrium density profiles and interfacial properties of polymer thin films in the presence of CO(2).
- To investigate the effects of CO(2) and film thickness on surface tension, CO(2) adsorption, and interface width.
- To explore the influence of polymer chain length on these interfacial characteristics.
Main Methods:
- Utilized polymer density functional theory (DFT) for theoretical analysis.
- Calculated equilibrium density profiles and interfacial parameters.
- Introduced a novel 'Delta profiles' method to quantify end-segment segregation.
Main Results:
- Observed changes in surface tension, CO(2) surface excess adsorption, and interface width due to CO(2) presence and increasing film thickness.
- Established an inverse linear relationship between interfacial properties and polymer chain length.
- Provided evidence of end-segment segregation towards the interface, enhanced by CO(2) and chain length.
Conclusions:
- CO(2) significantly influences the interfacial properties of polymer thin films.
- End-segment segregation is a key phenomenon, quantifiable with the new Delta profile method.
- The findings offer qualitative trends comparable to experimental and simulation studies, particularly for systems like octacosane-CO(2) near critical points.
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