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Multiple Segmental Processes in Polymers with cis and trans Stereoregular Configurations
Achillefs Pipertzis1, Andreas Hess2, Philipp Weis2
1Department of Physics, University of Ioannina, 45110 Ioannina, Greece.
ACS Macro Letters
|May 25, 2022
Summary
Altering polymer stereochemistry revealed unique dynamics. Cis-polymers exhibit complex segmental motions and low fragility, while trans-polymers can crystallize, showcasing stereochemistry
Area of Science:
- Polymer Science and Engineering
- Materials Science
- Physical Chemistry
Background:
- Polymer dynamics are crucial for material properties.
- Stereochemistry significantly influences polymer chain packing and behavior.
- Understanding local dynamics is key to designing advanced polymers.
Purpose of the Study:
- To investigate the impact of stereochemistry on polymer local dynamics.
- To explore the relationship between cis/trans isomerism and polymer motion.
- To characterize the unique dynamic processes in stereochemically altered polymers.
Main Methods:
- Synthesis of polymers with controlled cis/trans stereochemistry in the side group.
- Dynamic mechanical analysis and dielectric spectroscopy to probe segmental processes.
- Differential scanning calorimetry to determine glass transition temperature (Tg) and crystallization behavior.
Main Results:
- Cis-polymers displayed three segmental processes with Vogel-Fulcher-Tammann (VFT) temperature dependence.
- Cis-polymers exhibited low steepness index (m), indicating high fragility.
- The lowest reported pressure coefficient of Tg (dTg/dP) was observed in cis-polymers, linked to inefficient side-group packing.
Conclusions:
- Cis/trans stereochemistry profoundly impacts polymer local dynamics and packing efficiency.
- Inefficient packing in cis-polymers drives unique segmental motions and low Tg pressure dependence.
- The study highlights the role of stereochemistry and dipole arrangements in controlling both side-group and backbone dynamics.
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