Enhanced electroactive β-phase nucleation and dielectric properties of PVdF-HFP thin films influenced by montmorillonite and Ni(OH)2 nanoparticle modified montmorillonite

Abstract

The present work lays emphasis on the synthesis of electroactive and high dielectric poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP) composite films incorporated with montmorillonite (MMT) and Ni(OH)₂ nanoparticle (NP) modified MMT using a facile and low cost solution casting technique. Formation of Ni(OH)₂ NPs, different polymorphs and morphology of the composite samples have been investigated using UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and field emission scanning electron microscopy. A remarkable improvement in β-phase nucleation (∼85.22% for 1 mass% MMT doped at and 82.10% for 7.5 mass% NiMMT doped polymer composites films) and promising dielectric values are the standpoints of the work. Strong ion–dipole interaction between the negatively charged surfaces of MMT and –CH₂ dipoles of the polymer chains in the MMT loaded PVdF-HFP samples and formation of hydrogen bonds between the –OH group of Ni(OH)₂ NPs and F atom of the polymer chains in the Ni(OH)₂ NP-MMT/PVdF-HFP system play a dynamic role in enhancing the electroactive β-phase nucleation and the dielectric properties of the samples. A large accumulation of charges at the interfaces of the dopant and polymer matrix via Maxwell–Wagner–Sillars interfacial polarization effect occurred due to the disparity in the conductivity of the dopants and the polymer matrix is liable for the significant enrichment of dielectric properties of the composite films. Excellent thermal stability in dielectric properties has also been observed in these composite samples over a wide temperature spectrum. These electroactive and high dielectric polymer composite thin films may be potential candidates for application in piezoelectric nanogenerators, energy storage devices, thin film transistors and capacitive sensors etc.