A review on vital importance of beta phase in PVDF based carbon nanomaterial for sensing applications

Abstract Polyvinylidene fluoride (PVDF) is among the most encouraging piezoelectric polymers to be used in flexible and wearable sensors because of its electroactive -phase, which has the highest piezoelectric response and the best dipole alignment. Promoting and stabilizing this -phase crystallization would greatly improve the mechanical, dielectric, and electroactive properties of PVDF-based composites. The use of carbon nanomaterials, including carbon nanotubes (CNTs), carbon nanofibers (CNFs), graphene, carbon quantum dots (CQDs), and carbon nanodiamonds, has been shown to enhance the -phase content. Such nanofillers serve as nucleating agents, facilitate interfacial interactions, and enable charge transfer, thereby enhancing sensing performance. The methods of solution casting, electrospinning, in situ polymerization, and melt mixing have been used to optimize -phase formation. The electrospinning and in situ polymerization have been shown to be the most consistent in improving the process due to their greater control over chain alignment and nanofiller dispersion. Carbon nanotubes and graphene, in particular, are nanofillers that are especially effective at promoting -phase crystallization and offer high electrical conductivity, making them suitable for pressure, strain, and biomedical sensing. This review highlights the importance of promoting the -phase, selecting the nanofiller, and optimizing the synthesis strategy in developing PVDF-based carbon nanocomposites for next-generation sensing devices.