Large T g Shift in Hybrid Bragg Stacks through Interfacial Slowdown
Konrad Rolle1, Theresa Schilling2, Fabian Westermeier3
1Max-Planck-Institute of Polymer Research, Ackermannweg 10, Mainz 55128, Germany.
Macromolecules
|April 5, 2021
Summary
We demonstrate a novel nacre-mimetic Bragg stack for studying polymer glass transition (Tg) in confined thin films. This method reveals significant Tg increases and interfacial dynamics using X-ray photon correlation spectroscopy (XPCS).
Area of Science:
- Materials Science
- Polymer Physics
- Nanotechnology
Background:
- Confinement effects on polymer glass transition temperature (Tg) are crucial in thin films.
- Existing techniques for studying interfacial Tg often require highly specialized sample designs.
- Understanding polymer dynamics at interfaces is key to designing advanced materials.
Purpose of the Study:
- To develop a versatile platform for studying confined polymer thin films.
- To investigate glass transition and interfacial dynamics in a nacre-mimetic Bragg stack.
- To correlate structural periodicity with polymer behavior at interfaces.
Main Methods:
- Fabrication of nacre-mimetic clay/polymer Bragg stacks with controlled polymer layer thickness (monolayer and bilayer).
- Measurement of glass transition temperature (Tg) using standard thermal analysis.
- Application of X-ray photon correlation spectroscopy (XPCS) to probe interfacial dynamics.
Main Results:
- A significant increase in Tg (approximately 100 K) was observed for the polymer monolayer.
- XPCS revealed interfacial slowdown and platelet dynamics originating from the clay/polymer interface.
- Bilayers exhibited distinct Tg processes, confirming contributions from both bulk-like and interfacial regions.
Conclusions:
- The nacre-mimetic Bragg stack effectively allows for tunable confinement and enhanced signal for interface studies.
- XPCS is sensitive to clay/polymer interfacial dynamics, complementing Tg measurements.
- Engineered lattice spacing approaching interfacial layer dimensions enables significant Tg shifts and detailed interfacial studies.
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