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Thickness-Dependent Segmental Dynamics in Supported Thin Films: Insights from a Dynamically Correlated Network Model
Tatsuki Nakane1, Takashi Sasaki1
1Department of Materials Science and Engineering, University of Fukui, Fukui 9108507, Japan.
The Journal of Physical Chemistry. B
|September 3, 2024
Summary
This study models supported thin films of polystyrene, revealing how nanoconfinement affects glass transition dynamics. The findings explain the decoupling between thermodynamic and dynamic behaviors in supercooled liquids.
Area of Science:
- Materials Science
- Physical Chemistry
- Polymer Physics
Background:
- Nanoconfinement significantly alters supercooled liquid dynamics.
- A Dynamically Correlated Network (DCN) model describes cooperative rearrangements in supercooled liquids.
- Previous work validated the DCN model for freestanding polystyrene films.
Purpose of the Study:
- Adapt the DCN model for supported thin films.
- Investigate the influence of interfaces on polymer dynamics.
- Analyze the thickness and temperature dependence of glass transition in supported films.
Main Methods:
- Modified the DCN model by introducing virtual segments at interfaces.
- Simulated supported thin films of atactic polystyrene (PS).
- Evaluated cooperative cluster size, relaxation time, and glass transition temperature (Tg).
Main Results:
- The model predicts stronger Tg dependence on film thickness with increasing timescale.
- Simulated results align with experimental data for PS films across various timescales.
- Identified interfacial effects on polymer mobility and network dynamics.
Conclusions:
- The adapted DCN model accurately captures supported film dynamics.
- Provides insights into the origins of dynamical decoupling in confined polymers.
- Highlights the role of interfaces in modifying glass transition behavior.
