Improvement of β-phase crystal formation in a BaTiO₃-modified PVDF membrane

In this paper, low temperature plasma is used to modify the surface of barium titanate (BaTiO₃) nanoparticles in order to enhance the interfacial compatibility between ferroelectric poly (vinylidene fluoride)(PVDF) and BaTiO₃ nanoparticles. The results demonstrate that oxygenic groups are successfully attached to the BaTiO₃ surface, and the quantity of the functional groups increases with the treatment voltage. Furthermore, the effect of modified BaTiO₃ nanoparticles on the morphology and crystal structure of the PVDF/BaTiO₃ membrane is investigated. The results reveal that the dispersion of BaTiO₃ nanoparticles in the PVDF matrix was greatly improved due to the modification of the BaTiO₃ nanoparticles by air plasma. It is worth noting that the formation of a β-phase in a PVDF/modified BaTiO₃ membrane is observably promoted, which results from the strong interaction between PVDF chains and oxygenic groups fixed on the BaTiO₃ surface and the better dispersion of BaTiO₃ nanoparticles in the PVDF matrix. Besides, the PVDF/modified BaTiO₃ membrane at the treatment voltage of 24 kV exhibits a lower water contact angle (≈68.4°)compared with the unmodified one (≈86.7°). Meanwhile, the dielectric constant of PVDF/BaTiO₃ nanocomposites increases with the increase of working voltage.