Compression of Cross-Linked Poly(vinylidene fluoride-co-trifluoro ethylene) Films for Facile Ferroelectric Polarization

Department of Materials Science and Engineering, Yonsei University, Seoul, Korea.
ACS Applied Materials & Interfaces (Impact Factor: 5.9). 11/2011; 3(12):4736-43. DOI: 10.1021/am201202w
Source: PubMed

ABSTRACT In this study, we demonstrated a facile route for enhancing the ferroelectric polarization of a chemically cross-linked poly(vinylidene fluoride-co-trifluoro ethylene) (PVDF-TrFE) film. Our method is based on thermally induced cross-linking of a PVDF-TrFE film with a 2,2,4-trimethyl-1,6-hexanediamine (THDA) agent under compression. The remanent polarization (P(r)) of a metal/ferroelectric/metal capacitor containing a cross-linked PVDF-TrFE film increased with pressure up to a certain value, whereas no change in the P(r) value was observed in the absence of THDA. A film cross-linked with 10 wt % THDA with respect to PVDF-TrFE under a pressure of 100 kPa exhibited a P(r) of approximately 5.61 μC/cm(2), which is 1.6 times higher than that in the absence of pressure. The enhanced ferroelectric polarization was attributed to highly ordered 20-nm-thick edge-on crystalline lamellae whose c-axes are aligned parallel to the substrate. The lamellae were effective for ferroelectric switching of the PVDF-TrFE when a cross-linked film was recrystallized under pressure. Furthermore, compression of a PVDF-TrFE film with a topographically prepatterned poly(dimethyl siloxane) mold gave rise to a chemically cross-linked micropattern in which edge-on crystalline lamellae were globally oriented over a very large area.

  • [Show abstract] [Hide abstract]
    ABSTRACT: In solution-processes, the formation of multistacked layers (MSLs) is difficult because of natural dissolution and/or damage to the underlying film by the solvent used for the upper film To form MSLs in solution-processes, using orthogonal solvents for each layer is a representative remedy. As the number of MSLs increases, the selection of appropriate solvents for every layer becomes harder. In this work, we report a viable method to form MSLs, even when using one material for the entire solution-process. We present that solution-processed MSLs can be formed by tuning the solubility by mixing an orthogonal solvent. We fabricated ferroelectric MSLs using a ferroelectric polymer and applied the MSLs into a ferroelectric-gated field-effect transistor. We obtained improvements in electrical properties such as current on/off ratio, subthreshold swing, and mobility in transistors with MSLs, in comparison to the single layer case.
    Electronic Materials Letters 07/2014; 10(4). DOI:10.1007/s13391-014-3380-7 · 3.98 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene) (P(VDF-co-TrFE-co-CTFE)) with internal double bond has been reported with high dielectric constant and energy density at room temperature, which is expected to serve as a promising dielectric film in high pulse discharge capacitors. An environmentally friendly one-pot route, including the controllable hydrogenation via Cu(0) mediated single electron transfer radical chain transfer reaction (SET-CTR) and dehydrochlorination catalyzed with N-containing reagent, is successfully developed to synthesize P(VDF-co-TrFE-co-CTFE) containing unsaturation. The resultant polymer was carefully characterized with 1H NMR, 19F NMR, and FTIR. The composition of the resultant copolymer is strongly influenced by reaction conditions, including the reaction temperature, catalyst concentration, the types of ligands and solvents. The kinetics data of the chain transfer and elimination reaction demonstrate their well-controlled feature of the strategy. By shifting the equilibrium between the CTR and elimination reactions dominated by N-compounds serving as ligands in SET-CTR and catalyst in the dehydrochlorination of P(VDF-co-CTFE), P(VDF-co-TrFE-co-CTFE) with tunable TrFE and double-bond content could be synthesized in this one-pot route. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014
    Journal of Polymer Science Part A Polymer Chemistry 12/2014; 52(23). DOI:10.1002/pola.27410 · 3.54 Impact Factor