Thin poly(ionic liquid) and poly(vinylidene fluoride) blend films with ferro‐ and piezo‐electric polar γ‐crystals

Abstract

Ferro-and piezo-electric poly(vinylidene fluoride) (PVDF) thin film is reported to be obtained by using a poly(ionic liquid) (PIL) [poly(2-(dimethylamino)ethyl methacrylate) methyl chloride quaternary salt] through solution route. The short range interactions between localized cationic ions of PIL and polar >CF 2 of PVDF are responsible for modified polar c-PVDF (T 3 GT 3 G) formation. Modification in chain conformation of PVDF is confirmed by FTIR, XRD, and DSC studies suggesting the miscible PVDF-PIL (PPIL) blend. Up to 40 wt % loading of PIL in PVDF matrix enhances relative intensity of c-phase up to 50% in the entire crystalline phase. The P-E hysteresis loop of PVDF-PIL blends at 25 wt % PIL loading (PPIL-25) thin film at sweep voltage of 650 V shows excellent ferroelectric property with nearly saturated high remnant polarization 6.0 mC cm 22 owing to large proportion of c-PVDF. However, non-polar pure PVDF thin film shows unsaturated hysteresis loop with 1.4 mC cm 22 remnant polarization. The operation voltage decreases effectively because of the polar c-phase formation in PPIL blended film. High-sensitivity piezo-response force microscopy shows electromechanical switching property at low voltages in PPIL-25 thin films through local switching measurements, making them potentially suitable as ferroelectric tunnel barriers. V C 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 795-802 KEYWORDS: electromechanical switching property; ferroelectric property; polar c-crystals; poly(ionic liquid); poly(vinylidene fluoride) JOURNAL OF POLYMER SCIENCE WWW.POLYMERPHYSICS.ORG FULL PAPER FIGURE 5 Hysteresis loops of P versus applied V of (a) PVDF and its blends at maximum sweep voltage 50 V, (b) PPIL-25 at loading of 25 wt % of PIL as a function of applied V. [Color figure can be viewed at wileyonlinelibrary.com] FIGURE 6 (a 1 , b 1 ) PFM amplitude and phase images, respectively, of a thin PVDF film by applying 10 V DC voltage, there is no ferroelectric domains written on PVDF films due to insufficient direct current (DC) voltage. (a 2 , b 2 ) PFM amplitude and phase and images, respectively, of a thin PPIL-25 film by applying 10 V DC voltage. (c 1 , d 1 ) PFM amplitude and phase and images, respectively, of a thin PVDF film by applying 10 V DC voltage. (c 2 , d 2 ) PFM amplitude and phase and images, respectively, of a thin PPIL-25 film by applying 30 V DC voltage. [Color figure can be viewed at wileyonlinelibrary.com]

Poly(ionic liquid) composites

“…An example is illustrated here by the combination of poly(vinylidene fluoride) (PVDF) with a poly(2-(dimethylamino)ethyl methacrylate) methyl chloride; in this case a film is fabricated through noncovalent interactions between the localized cationic ions of the PIL and the polar -CF 2 group of PVDF, which results in a PIL-PVDF composite film featuring excellent ferroelectric properties. 140 PIL-polymer membranes are useful in electrochemical devices. In particular, PIL-based electrolytes are selected for memory devices because of their advantages of mechanical stability, safety, good processability and moderate ionic conductivity.…”

New developments in composites, copolymer technologies and processing techniques for flexible fluoropolymer piezoelectric generators for efficient energy harvesting

“…Interestingly, Tiwari et al 201 have shown the formation of the γ phase in PVDF upon the incorporation of a poly(ionic liquid), poly(2-(dimethylamino)ethyl methacrylate) methyl chloride quaternary salt. Here, the poly(ionic liquid) is added to the PVDF in solution at loadings up to 50 wt% and thin films are then solvent cast.…”

Ionic Liquid Assisted α–γ′ Phase Transition of Poly(vinylidene fluoride) Thin Films

“…Among these phases, the α-phase is a nonpolar phase and can be used only as ordinary plastic. The polar β- and γ-phases, especially the γ-phase serve as a rather good candidate for fabricating thermally stable devices with long endurance because of its excellent thermodynamic stability and the highest Curie temperature. , They are, however, not easily obtained. , There are two types of γ-PVDF crystallites discriminated from their formation procedures. One of them, designated as γ form, is obtained directly from the melt crystallization at extremely high temperatures.…”