Flexible Self-standing Films Research Articles

Boosting Energy Storage of Poly(vinylidene difluoride) Nanocomposite Based Flexible Self-Standing Film with Low Amount of Hydroxylated V2O5

Polymer-ceramic based nanocomposite dielectric materials have become an attraction for researchers due to their lightweight and high dielectric breakdown strength as well as good dielectric properties. We have synthesized poly(vinylidene difluoride) (PVDF)/hydroxylated-V2O5 (Hy-V2O5) ferroelectric polymer nanocomposite self-standing film, with an average thickness of 0.07 ± 0.005 mm. The phase identification, surface analysis, and structural analysis were performed using differential scanning calorimetry, X-ray photoelectron spectroscopy analysis, and X-ray diffraction, respectively. The analysis of atomic force micrographs reveals lower surface roughness of the nanocomposite films and confirms that the film is suitable for energy storage rather than charge transport with the help of the isotropic power spectral density (PSD) profile. The loading of a low amount of Hy-V2O5 filler in PVDF significantly enhances the ferroelectric polarization, making it highly suitable for high energy storage applications. Enhancement of the dielectric constant (from ∼9 to 29.86) and polarization (Pmax for PVDF = 0.86 μC/cm2 to Pmax for PVDF/Hy-V2O5 = 2.7 μC/cm2 at the 1000 kV/cm field) is obtained. The energy density for the nanocomposite increased to 220% of that of the pure PVDF. Due to the low amount of filler, there is no substantial reduction in the dielectric breakdown strength of the nanocomposite, which is maintained at 1766.93 kV/cm.

Preparation and luminescence performance of flexible films based on curdlan derivatives and europium (III) complexes as luminescent sensor for base/acid vapor

Herein we manifested an alternative route to synthesize water-soluble biopolymers from natural polysaccharides by chemically modifying aminated curdlan with succinic acid (SA) or ionic liquid (IL), and a series of flexible self-standing films were made from the homogeneous solutions consisting of europium(III) complexes in nanoclay and the above biopolymers under aqueous conditions, which are transparent and luminescent. Compared to film without curdlan derivatives, the presence of water-soluble decorated curdlan can significantly enhance the luminescence efficiency and improve photoluminescent stability of the films. Enhancements of the luminescent intensity were further remarkable when exposing the films to triethylamine vapor, while obvious luminescence quenching occurred upon exposure to HCl vapor. The films are encouraging optoelectronic detectors and vapor-sensitive luminescent sensors.

Amphiphilic silsesquioxane nanoparticles by hydrolytic condensation of Y-shaped triethoxysilanes having hydroxyl and fluoroalkyl groups: Synthesis, self-assembly, and surface properties

Two Y-shaped molecules combining two dissimilar (hydrophilic and hydrophobic) units with a reactive triethoxysilane moiety were synthesized by Michael addition reaction of (aminopropyl)triethoxysilane with 2-hydroxyethyl acrylate (HEA), followed by the addition of 2,2,2-trifluoroethyl acrylate (TFEA) or 1H,1H,5H-octafluoropentyl acrylate (OFPA). Hydrolytic condensations of the Y-shaped triethoxysilane precursors proceeded as homogeneous systems in acetone in presence of the acidic catalyst to afford amphiphilic silsesquioxane nanoparticles (SQ-NPs) having hydroxyl and fluoroalkyl groups (HEA/TFEA-SQ and HEA/OFPA-SQ). Scanning force microscope (SFM), X-ray diffraction (XRD), and size-exclusion chromatography (SEC) measurements indicated the formation of nanoparticles (average particle diameter is about 2.0 nm) with reasonable molecular weights and low dispersities (Mn = 5100-5400, Mw/Mn = 1.22–1.36) without aggregation. Characteristic assembled structures and surface properties of the amphiphilic SQ-NPs in different solvents were also evaluated. Flexible self-standing films were obtained from the amphiphilic SQ-NPs without any additional compounds, which are due to intermolecular hydrogen bondings.

Carboxyl-Functionalized Ionic Liquid Assisted Preparation of Flexible, Transparent, and Luminescent Chitosan Films as Vapor Luminescent Sensor.

Herein we present a novel method to synthesize flexible self-standing films consisting of europium(III) complexes in nanoclay and chitosan, which are transparent and luminescent. Preparation takes place under aqueous conditions assisted by a carboxyl-functionalized ionic liquid (IL). The latter is used not only as a replacement for acetic acid to dissolve chitosan but, surprisingly, also to enhance the luminescence efficiency of the final films. A brighter luminescence is observed for the films prepared assisted with the ionic liquids compared to those by using acetic acid. The reason is that the ionic liquid used to dissolve chitosan can decrease proton strength on embedded platelets primarily through ion-exchange process and thus can increase the coordination number of europium(III) complexes. Exposure of the films to Et3N vapors can cause a further remarkable luminescence enhancement, while significant luminescence quenching occurred upon exposure to HCl vapors. The films are promising for applications in areas such as optoelectronics and vapor-sensitive luminescent sensors.

The Ionogel of N-Butyl-N-Methylpyrrolidinum Bis(trifluoromethanesulfonyl) Imide and Polyvinylidenefluoride-Co-Hexafluoropropylene for Flexible Lithium Ion Battery

Rechargeable lithium ion batteries (LIBs) have been applied in portable electronics and electricity powered transportation due to the high energy and power density. Unlike the traditional batteries packed in a cylindrical type, currently, most LIBs used in the consumer electronics (like smart phones and pads) are prismatic batteries. To meet the requirement of the electronics with particular shape such as wearable devices the flexible energy storage devices have been developed. For the safety concern, the solid electrolytes, such as polymer electrolyte, are developed to avoid leakage of liquid electrolyte. Nevertheless, the larger interfacial resistance between the solid electrolyte and electrodes and less flexibility reduced its application. Therefore, the gel-type electrolytes are favored because lithium ion is more easily to transport in gel electrolyte than solid electrolyte. Yet, as reported, certain amount of the organic solvents such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) have been usually used with polymers in the traditional gel electrolytes, causing the suspicion of solvent leakage. In this work, the solvent-free polymer-based ionogel electrolyte (IGE) composed of nonflammable and thermally stable N-butyl-N-methylpyrrolidinum bis(trifluorome­thanesulfonyl) imide (PYR14TFSI) room temperature ionic liquid and polyvinylidenefluoride-co-hexafluoropropylene (P(VdF-HFP)) are prepared by the solution casting method. The thermal and electrochemical properties are determined by the DSC and DMA measurements. The electrical properties are investigated by the linear sweep voltammetry, cyclic voltammetry and impedance spectroscopy. It is found that the as-prepared ionogel electrolytes are flexible self-standing films with wide electrochemical windows. The best conductivity obtained at room temperature is 6.0 × 10−4 S cm−1. The highest capacity of the half-cell (Li/IGE/LiFePO4) achieves 143 mA h g-1 at 0.2C rate. And even after 50 cycles, the capacity retains 135 mA h g-1at 0.2C. This study reveals that the ionogel electrolyte is a promising safe electrolyte for application in the flexible LIBs. Acknowledge: The authors gratefully acknowledge the Ministry of Science and Technology and Chung Yuan Christian University, Taiwan, R. O. C. for supporting this research work.

Microwave-Assisted Polycondensation via Direct Arylation of 3,4-Ethylenedioxythiophene with 9,9-Dioctyl-2,7-dibromofluorene

For synthesis of π-conjugated polymers, polycondensation via direct arylation reactions of C–H bonds in aromatic monomers with dibromo-arylenes has attracted increasing attention as a simple synthetic method in which the preparation of organometallic reagents is unnecessary. To develop direct arylation polycondensation for practical use in the synthesis of optoelectronic polymer materials, microwave-assisted reactions were investigated and optimized in terms of a kind of base, concentration, reaction time, and amount of catalyst. Under the optimized conditions, the microwave-assisted direct arylation of 3,4-ethylenedioxythiophene with dibromofluorene for 30 min with catalyst (1 mol %) gave the corresponding polymer with an extremely high molecular weight up to 147 000. The high molecular weight of the polymer enables formation of a large and flexible self-standing film, leading to an advantage in fabricating organic thin-film devices. The elemental analysis and MALDI-TOF-MS reveal that the polymer has hig...

Transparent and luminescent ionogels based on lanthanide-containing ionic liquids and poly(methyl methacrylate) prepared through an environmentally friendly method

We report here on a simple and environmentally friendly procedure for preparing transparent, luminescent ionic liquid-containing poly(methyl methacrylate) (PMMA) ionogels in the form of monoliths, films and flexible self-standing films. Lanthanide oxides and organic ligand were firstly dissolved in carboxyl-functionalized ionic liquids to form a lanthanide complex-containing ionic liquid, which was then dissolved in methyl methacrylate (MMA) monomer without using any organic solvents. The following polymerization process leads to transparent materials (monolith, film and flexible self-standing film) containing ionic liquids, PMMA and a lanthanide complex, which are highly luminescent under UV-light irradiation.

Highly flexible self-standing film electrode composed of mesoporous rutile TiO2/C nanofibers for lithium-ion batteries

There is increasing interest in flexible, safe, high-power thin-film lithium-ion batteries which can be applied to various modern devices. Although TiO2 in rutile phase is highly attractive as an anode material of lithium-ion batteries for its high thermal stability and theoretical capacity of 336mAhg−1 and low price, its inflexibility and sluggish lithium intercalation kinetics of bulk phase strongly limit its practical application for particular in thin-film electrode. Here we show a simple way to prepare highly flexible self-standing thin-film electrodes composed of mesoporous rutile TiO2/C nanofibers with low carbon content (<15wt.%) by electrospinning technique with outstanding electrochemical performance, which can be applied directly as electrodes of lithium-ion batteries without the further use of any additive and binder. The atmosphere during calcination plays a critical role in determining the flexible nature of thin film and particle size of TiO2 in as-fabricated nanofibers. Big size (10cm×4cm), flexible thin film is obtained after heat treatment under 10%H2–Ar at 900°C for 3h. After optimization, the diameter of fibers can reach as small as ∼110nm, and the as-prepared rutile TiO2 films show high initial electrochemical activity with the first discharge capacity as high as 388mAhg−1. What is more, very stable reversible capacities of ∼122, 92, and 70mAhg−1 are achieved respectively at 1, 5 and 10C rates with negligible decay rate within 100 cycling times.

Properties of flexible, transparent barium titanate nanoparticle/poly(2-hydroxyethyl methacrylate) hybrid

A transparent BaTiO3 particle/poly(2-hydroxyethyl methacrylate) (PHEMA) hybrid was synthesized from a Ba–Ti double alkoxide modified with an organic ligand, and the refractive index and ferroelectric properties of the hybrid were studied. The transparent hybrid was flexible and could be shaped not only in the form of thin films on substrates but also in the form of flexible self-standing films. BaTiO3 particles around 5 nm in diameter were dispersed uniformly in the polymer matrix. The refractive indexes of the hybrid films increased with decreasing wavelength and were dependent on the volume fractions of the BaTiO3 and polymer phases. The hybrid film synthesized at a molar ratio of BaTiO3:2-vinlyloxyethanol:H2O:PHEMA = 1:8:30:5 gave the best result, with a refractive index of 1.55 at 589 nm and an Abbe number of 37.5. A transparent hybrid film on platinized silicone substrates exhibited a polarization–electric field hysteresis loop.

Flexible transparent self-standing binderless clay film prepared by hydrothermally-treated synthetic clay

A transparent flexible self-standing film with high heat resistance was formed from hydrothermally-treated synthetic clay without binders; the hydrothermal treatment engendered the clay particle growth; the treatment at 400 °C yielded the enlarged particles over 10 000 nm, which were 300 times as larges as those of the original clay. The film prepared by the particles showed the good film formability/flexibility that originated from the change in the stacking structure affected by the particle size.

Preparation of a transparent and flexible self-standing film of layered titania/isostearate nanocomposite

A titania-based self-standing film with high transparency and flexibility was successfully prepared via a sol-gel process, in which a titanium tetraisopropoxide/isostearate complex (precursor), n-hexylammonium isostearate (catalyst), and o-xylene (solvent) were used. The sol obtained by the sol-gel reaction was floated on a water surface to form an unsupported film. This film was composed of a titania/isostearate nanocomposite with ordered layer structure. The basal spacings of the nanocomposites depended on the chain length of the carboxylate modifier.

Preparation of a Transparent and Flexible Self-Standing Film of Layered Titana/Isostearate Nanocomposite by Hydrophobic Sol-Gel Process

Preparation of a Transparent and Flexible Self-Standing Film of Layered Titana/Isostearate Nanocomposite by Hydrophobic Sol-Gel Process

Nanostructured anisotropic ion-conductive films.

A flexible self-standing film with layered nanostructures was obtained by in situ photopolymerization of a new smectic liquid-crystalline monomer containing a tetra(oxyethylene) moiety, which forms a macroscopically oriented complex with lithium salts. The resultant films show two-dimensional ionic conductivity.