Enhanced dielectric and electrical properties of polystyrene-2% divinyl benzene (PDB) embedded in SrTiO3-Poly (vinylidene fluoride) three phase composite films

Abstract

A facile solution casting technique has been employed to fabricate ceramic SrTiO3; STO particle and polystyrene-2% divinyl benzene (PDB) filled three phase composite films using poly(vinylidene fluoride) (PVDF) matrix. The frequency dependence of dielectric and electrical properties of the three phase PVDF-STO-PDB composite films of various weight percentage of PDB (fPDB) were analyzed. With the small change in the AC conductivity and dielectric loss the dielectric constant of the PVDF-STO-PDB composite systems is improved noticeably. The experimental results suggested that, the introduction of 10 wt% of PDB particles in the PVDF-STO composites enhanced the dielectric constant (≈76) and suppressed dielectric loss value (< 0.5) at 100 Hz. This may be attributed to the addition of PDB particles improved the establishment of polarization. The morphological analysis depicts that the PDB particles are uniformly dispersed and well compatibility between filler particles and polymer matrix which may be ascribed to the minimization of dielectric loss of the resultant composites. Further, the strong interaction between PDB particles and PVDF matrix at the interface is the crucial factor in the improvement of the dielectric and electrical properties. The percolation theory was used to elucidate the dielectric and electrical performance of PVDF-STO-PDB composites. It is noticed that the three phase PVDF-STO-PDB composite films exhibited an insulator-conductor transition with percolation threshold of fPDB = 5 wt%. The three phase composites with high dielectric constant (≈76) at percolation threshold might be helpful to understand the influence of PDB particles on the interfaces between the ceramics and polymer matrix. This work will provide an easy and effective solution to fabricate high performance three phase composites to the development of high energy storage applications.