Structural and Dielectric Properties of Flexible PVDF/Hydroxyapatite Nanocomposite Films

The field of biomaterial research is a multidisciplinary pursuit, which focuses on the development of new biomaterials that can replace bad organs and tissues to enhance life expectancy. The biological activities in natural bone such as the biodegradation process are closely related to its piezoelectric properties through regular movement and accumulation of electrical charges during most of the physiological processes. The polarizability due to this charge accumulation contributes to the cellular activities that favor bone growth and tissue regeneration. This signifies the need for ferro- and piezoelectric materials in bone implants and tissue engineering scaffolds. Such alternate ferro- and piezoelectric biomaterial-based implants can enhance tissue regeneration at the impaired sites by the creation and transfer of bioelectric signals similar to that of natural tissues. The high dielectric permittivity of these materials enhances the surface charge formation and polarizability, thereby shortening the bone regeneration time. In this perspective, we propose a novel polymer nanocomposite piezoelectric material with high dielectric permittivity suitable for bone and cartilage tissue engineering. We have fabricated a novel piezoelectric polymer nanocomposite film by the solution cast method, in which ferroelectric hydroxyapatite (HA) nanoparticles (nanofillers) with different weight percentages (0, 5, 10, and 15%) were incorporated in the polyvinylidene difluoride (PVDF) polymer matrix. The structural properties of the HA nanoparticles were analyzed using X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), and micro-Raman spectroscopy techniques. The structural properties of the freestanding films of PVDF-HA were analyzed using X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) techniques. The electrical and dielectric properties of the thin film samples were analyzed at room temperature to highlight the effect of filler loading on the effective permittivity, dielectric loss, and ferroelectric polarization of the polymer nanocomposite films.