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Physical Aging of Star-Shaped Macromolecules
Bradley Frieberg, Emmanouil Glynos, Georgios Sakellariou1
1Department of Chemistry, University of Athens, Panepistimiopolis, Zografou, 15771, Athens Greece.
ACS Macro Letters
|May 24, 2022
Summary
Star-shaped polystyrene macromolecules exhibit slower physical aging rates compared to linear chains. This difference is influenced by molecular architecture, with increased functionality and decreased arm molecular weight accelerating aging suppression.
Area of Science:
- Polymer Science
- Materials Science
- Physical Chemistry
Background:
- Physical aging is a critical phenomenon affecting polymer properties over time.
- Structural relaxations in amorphous polymers are influenced by molecular architecture.
- Understanding aging in star-shaped polymers is crucial for material stability.
Purpose of the Study:
- To investigate time-dependent structural relaxations and physical aging in star-shaped polystyrene (SPS) films.
- To compare the aging rates of star-shaped polystyrene with its linear analogs.
- To determine the influence of star polymer architecture (functionality and arm molecular weight) on aging rates.
Main Methods:
- Experimental investigation of physical aging in thin films (0.4 μm < H < 2 μm).
- Analysis of time-dependent structural relaxations in star-shaped polystyrene.
- Comparative study with linear polystyrene chains.
Main Results:
- Star-shaped polystyrene macromolecules demonstrate significantly slower physical aging rates than linear polystyrene.
- The difference in aging rates increases with higher functionality (f) and lower molecular weight per arm (Mnarm).
- Architectural constraints in star polymers suppress relaxations and free volume reduction.
Conclusions:
- The unique architecture of star-shaped polymers effectively hinders physical aging processes.
- Molecular design, specifically functionality and arm molecular weight, can be leveraged to control polymer aging.
- These findings provide insights into the structure-property relationships governing polymer dynamics and stability.
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