Spatially Confined Fabrication of Polar Poly(Vinylidene Fluoride) Nanotubes

Abstract

Polar poly(vinylidene fluoride) (PVDF) nanotubes have attracted significant attention due to their excellent piezoelectric and ferroelectric properties, yet a tunable fabrication of homogeneous polar PVDF nanotubes remains a challenge. Here, a simple method is reported to fabricate polar PVDF nanotubes using anodize aluminum oxide (AAO) membranes as templates that are removed by etching in a potassium hydroxide (KOH) solution and then ageing at room temperature. PVDF nanotubes originally crystallized in the AAO membrane are pure α‐crystals with very low crystallinity, yet after being released from the templates, the crystallinity of the nanotubes markedly increases with ageing at room temperature, leading to the formation of β‐PVDF crystals in a very short time, with the formation of γ crystals after longer ageing times. A large amount of γ crystals formed when the released PVDF nanotubes are heated to ≈130 °C. The formation of polar PVDF nanotubes released from the AAO templates treated with higher concentrations of alkaline solution results from the reaction of the surface of the PVDF nanotubes with the alkaline solution and structure reorganization under confined conditions. This large‐scale preparation of β‐ and γ‐PVDF opens a new pathway to produce polar PVDF nanomaterials.

Tailoring Electroactive β- and γ-Phases via Synthesis in the Nascent Poly(vinylidene fluoride) Homopolymers

“…The exclusivity of the diffraction peak associated with the crystal plane (021) for the α-phase (Figure c,d) and the crystal plane (140) for the γ-phase (Figure a,b) allows making the distinction between the two phases. The presence of the β-phase is identified by a well-defined diffraction peak at 2θ = 20.3° associated with the overlapping of the (110) and (200) diffraction planes of the β-phase. ,− The complementary FTIR, Raman, and WAXD techniques allow for the exact identification and quantification of the PVDF crystalline phases.…”

Scaffold-Based Poly(Vinylidene Fluoride) and Its Copolymers: Materials, Fabrication Methods, Applications, and Perspectives

“…Significant progress has been made in fabricating scaffolds by solvent casting molding. During the process, pouring polymers dissolved in organic solvents onto glass substrates or molds to obtain desired structures. − By adjustment of the polymer concentration, the solvent volatilization rate, and the solution fluidity, precise control of the porous structure can be achieved. For example, Arumugam et al fabricated a porous film by solution casting and drying at 70.0 °C, with a porosity of 69.0% .…”

The tuning of crystallization behavior of ferroelectric poly(vinylidene fluoride‐co‐trifluoroethylene)

“…Nanoconfinement also plays a critical role in determining the crystal phase by causing different alignment of dipoles. [114][115][116][117][118][119][120][121][122][123][124] Nanostructures of P(VDF-TrFE) can be fabricated by different routes, such as template-assisted fabrication, nanoimprint lithography, and electrospinning. 125,126 The template-assisted approach is based on the infiltration of the polymer melt or solution into the porous templating matrix.…”

“…Nanoconfinement also plays a critical role in determining the crystal phase by causing different alignment of dipoles 114–124 . Nanostructures of P(VDF–TrFE) can be fabricated by different routes, such as template‐assisted fabrication, nanoimprint lithography, and electrospinning 125,126 .…”