Dielectric Characterization of Core-Shell Structured Poly(vinylidene fluoride)-grafted-BaTiO₃ Nanocomposites

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Poly(vinylidene fluoride) (PVDF) is a versatile polymer with significant dielectric applications.
• BaTiO3 (BT) nanoparticles are known for their excellent dielectric and piezoelectric properties.
• Developing effective methods to combine PVDF and BT at the nanoscale is crucial for enhancing composite performance.

Purpose of the Study:

• To investigate the dielectric properties of PVDF-grafted-BaTiO3 (PVDF-g-BT) core-shell structured nanocomposites.
• To understand the influence of the interfacial core-shell structure on dielectric behavior.
• To explore the impact of Reversible Addition Fragmentation chain Transfer (RAFT) polymerization on material properties.

Main Methods:

• Broadband Dielectric Spectroscopy (BDS) was used to analyze dielectric properties.
• Reversible Addition Fragmentation chain Transfer (RAFT) polymerization was employed to synthesize the nanocomposites.
• Thermal analysis (DSC) was performed to characterize material transitions.

Main Results:

• The dielectric constant of PVDF-g-BT increased with BT content, showing a +50% enhancement at 15 vol% BT.
• The observed dielectric enhancement was approximately 40% higher than predicted by conventional composite models, attributed to the core-shell interface.
• PVDF's characteristic dielectric relaxations were maintained, while a new relaxation linked to interfacial polarization at amorphous-crystalline interfaces was identified.
• Thermal analysis revealed a broad endotherm, potentially from ungrafted PVDF fractions.

Conclusions:

• The core-shell structure in PVDF-g-BT nanocomposites significantly enhances dielectric properties beyond conventional predictions.
• RAFT polymerization yields highly crystalline materials, leading to unique interfacial polarization phenomena.
• The study highlights the potential of tailored interfacial engineering in designing advanced dielectric nanocomposites.