Role of solvent polarity in controlling the formation of electroactive β/γ-phases in poly(vinylidene fluoride) nanoparticles

ABSTRACT We systematically investigate the dominant role of solvent polarity in the formation of electroactive phases of poly(vinylidene fluoride) (PVDF) by combining comprehensive experimental characterization (IR spectroscopy, X-ray scattering, Atomic Force Microscopy) with molecular dynamics (MD) simulations. We demonstrate that the solvent dipole moment dictates the stabilization of polar chain conformations in the solution and, consequently, the crystallization of electroactive β and γ polymorphs (reported here jointly as β/γ) in both solvent-cast bulk deposits and water-dispersed nanoparticles (NPs). A critical dipole-moment threshold of μ ≈ 2.8 D is identified: solvents above this value consistently yield electroactive phase contents exceeding 50 %, regardless of the processing route. MD simulations reveal that polar solvents strengthen PVDF–solvent dipole coupling and increase the population of all-trans (TTT) conformers, in agreement with the experimentally determined electroactive fractions. Furthermore, the incorporation of water as a polar antisolvent during nanoprecipitation enhances the electroactive phase content of the crystallites in NPs relative to bulk samples. The combined experimental–computational approach provides a unified molecular-level understanding of solvent-driven polymorph selection in PVDF and offers practical guidelines for solvent and process design to engineer high-performance electroactive PVDF structures from the macro- to the nanoscale.