Ferroelectric Polymers Exhibiting Negative Longitudinal Piezoelectric Coefficient: Progress and Prospects.
1Department of Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|March 21, 2020
Summary
Negative piezoelectric coefficients in polymers originate from crystalline electrostriction, not amorphous regions. This finding enables improved electromechanical properties through structural engineering of ferroelectric polymers.
Area of Science:
- Materials Science
- Polymer Physics
- Solid State Physics
Background:
- Piezoelectric polymers are crucial for flexible, wearable, and biocompatible devices.
- Ferroelectric polymers like PVDF and its copolymers exhibit superior piezoelectric coefficients.
- The physical origin of negative longitudinal piezoelectric coefficients in these polymers is not well understood.
Purpose of the Study:
- To elucidate the underlying physical mechanism of negative longitudinal piezoelectric coefficients in ferroelectric polymers.
- To resolve controversies surrounding existing theoretical models for piezoelectricity in polymers.
- To identify pathways for enhancing the electromechanical performance of piezoelectric polymers.
Main Methods:
- Revisiting and critically reviewing various theoretical models proposed over decades.
- Analyzing the contributions of crystalline, amorphous, and interfacial regions to piezoelectricity.
- Focusing on the role of electrostriction in the crystalline domain.
Main Results:
- Negative longitudinal piezoelectric coefficients are definitively attributed to negative longitudinal electrostriction within the crystalline domain.
- The amorphous and crystalline-amorphous interfacial regions do not contribute to this phenomenon.
- The crystalline origin provides a clear target for material design.
Conclusions:
- The piezoelectricity in polymers is fundamentally rooted in their crystalline structure.
- Understanding and engineering the crystalline domain, particularly through morphotropic phase boundaries, can optimize electromechanical properties.
- This research opens avenues for advanced material design in flexible electronics and energy harvesting.
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