Exclusive self-aligned β-phase PVDF films with abnormal piezoelectric coefficient prepared via phase inversion

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Poly(vinylidene fluoride) (PVDF) is a versatile polymer with unique piezoelectric properties.
• Controlling PVDF polymorphism is crucial for optimizing its performance in various applications.
• Existing methods for PVDF film preparation can be complex or yield mixed-phase results.

Purpose of the Study:

• To develop a facile method for producing self-polarized PVDF films with controlled polymorphism.
• To investigate the effect of quenching temperature on PVDF phase formation and self-alignment.
• To evaluate the piezoelectric properties of the resulting PVDF films for potential applications.

Main Methods:

• A phase-inversion technique was employed to fabricate PVDF films.
• Quenching temperatures were varied from 100 °C to -20 °C to control polymorphism.
• PVDF film polymorphism was analyzed, focusing on the transition from α-phase to β-phase.
• Piezoelectric coefficients were measured to quantify film performance.

Main Results:

• PVDF films with exclusive α-phase (>90%) were obtained at 100 °C.
• PVDF films with predominantly β-phase (>98%) were achieved at -20 °C.
• Low-temperature quenching resulted in self-aligned β-phase crystallites.
• A high piezoelectric coefficient of up to -49.6 pm V⁻¹ was recorded for the β-phase films.

Conclusions:

• The quenching temperature in the phase-inversion process is a critical parameter for controlling PVDF polymorphism.
• The developed method efficiently produces highly crystalline β-phase PVDF films with excellent self-alignment.
• These PVDF films exhibit significant piezoelectric properties, making them promising for electroactive devices and energy harvesting.