Effect of solvents on the crystal formation of poly(vinylidene fluoride) film prepared by a spin-coating process

Abstract

The effect of the solvent evaporation rate and solvent type on the crystal formation of poly(vinylidene fluoride) (PVDF) prepared by spin-coating was evaluated over time. In the much-solvent-remaining state, the crystalline phase of PVDF changed in the order of , , and  with the increasing dipole moment of the solvent. In the almost-all-solvent-evaporated state, the crystalline structure of PVDF/hexamethylphosphoramide with a higher dipole moment was dominantly dependent on the evaporation rate and varied in the order of ,  and  with the increasing solvent evaporation rate. However, PVDF/triethyl phosphate, having a lower dipole moment, always formed the  phase, regardless of the evaporation rate. The PVDF  phase in the concentrated solution state is difficult to transform into the  and  phases because the potential energy of each PVDF crystalline phase increases in the order of , , and . The PVDF crystalline phase in the spin-coating method is strongly affected by both the polymer-solvent electrostatic interactions and the evaporation conditions. From the results of the crystal transition behavior, it was experimentally supported that the potential energy of the PVDF crystalline structure increases in the order of , , and .

Piezoelectric materials as stimulatory biomedical materials and scaffolds for bone repair

“…These methods have been reviewed in detail by Lanceros-Mendez et al [116]. Two recent works by H. Horibe et al have highlighted the control of phases using different solvents and anti-solvents during synthesis procedure [122,123]. It was observed that a solvent with higher dipole moment resulted in formation of polar βphase which was also supported by slower solvent evaporation rate [122,123].…”

Characterization and Application of PVDF and Its Copolymer Films Prepared by Spin-Coating and Langmuir–Blodgett Method

“…Due to the simple process and good quality of prepared films, there has been a considerable amount of research on prompting the formation of β phase in spin-coated PVDF films [18,22,25,[35][36][37][38][39][40][41][42][43][44][45]. The general process can roughly be divided into three steps: solution preparation, spin-coating, and annealing.…”

“…Firstly, as PVDF and its copolymers are dissolvable in many kinds of organic polar solvents (e.g., diethyl carbonate, dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), and dimethylsulfoxide (DMSO)), subtle variations deriving from the solvent used have been reported. Nishiyama et al evaluated how the solvent evaporation rate and solvent type influence the crystal formation in spin-coated PVDF films over time, and concluded that both the polymer-solvent electrostatic interactions and the evaporation conditions play important roles [42]. Additionally, by adding nucleating fillers like clay [46], hydrated salt [35], or nanoparticles such as CeO 2 [47], palladium [48], or gold [49], the electroactive β phase can be enhanced.…”

Experimental and theoretical studies on the formation of pure β-phase polymorphs during fabrication of polyvinylidene fluoride membranes by cyclic carbonate solvents

“…Conversely, when PVDF is dissolved in solvents with a lower dipole moment, the solvent interacts less strongly with PVDF and results in the formation of unexpanded or shrunken globules favoring therefore the twisted α-phase conformation. 64 It must be mentioned that hydrogen bonding at the interface of PVDF and solvent is another key factor governing β-phase formation. Interfacial hydrogen bonds are formed between hydrogen or fluorine atoms in PVDF and the solvent.…”