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Published on: February 7, 2017
Polarization effects and phase equilibria in high-energy-density polyvinylidene-fluoride-based polymers
V Ranjan1, L Yu, Serge Nakhmanson
1Center for High Performance Simulation and Department of Physics, North Carolina State University, Raleigh, NC 27695-7518, USA.
Summary
Polyvinylidene fluoride (PVDF) copolymers undergo phase transitions controlled by copolymerization. Applied electric fields induce transitions from the alpha to beta phase, enabling efficient electrical energy storage.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Polymer Science
Background:
- Polyvinylidene fluoride (PVDF) and its copolymers exhibit distinct nonpolar (alpha) and polar (beta) phases.
- Understanding phase transitions is crucial for optimizing material properties and applications.
Purpose of the Study:
- To investigate the phase diagrams of PVDF and its copolymers under applied electric fields.
- To elucidate the role of copolymerization degree in structural phase transitions.
Main Methods:
- Utilizing first-principles calculations to model phase behavior.
- Analyzing phase transitions between alpha and beta phases under varying electric fields.
Main Results:
- Copolymerization degree is a key factor controlling structural phase transitions.
- PVDF-TeFE stabilizes in the beta phase for tetrafluoroethylene (TeFE) concentrations above 12%.
- Applied electric fields induce alpha to beta phase transitions in lower concentration domains, up to a breakdown field of ~600 MV m(-1).
Conclusions:
- Structural phase transitions in PVDF copolymers are tunable via copolymerization and electric fields.
- These field-induced transitions offer potential for advanced electrical energy storage applications.
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