Research on the microstructure-based modeling of composite dielectrics for capacitor applications is described. Methods for predicting the composite dielectric permittivity and internal electric field distributions within the microstructure using finite difference quasi-electrostatic modeling are described, along with methods of generating realistic model spaces of particulate microstructures. An existing algorithm for generating random, monosized spheres-in-a-dielectric matrix model spaces is modified to allow the treatment of bimodal composites in which small particles are deliberately segregated into the spaces between large particles. Such composites can have substantially higher total volumetric filling fractions of particles, leading to higher composite permittivity. The variations in permittivity with the filling fractions of bimodal inclusions are studied with the new model, with cases covering three different types of polymer matrix material. The effect of the small particle additions on the electric field statistics within the polymer matrix is also explored.

Ion transport across cell membranes happens through protein channels and pumps expending concentration gradients, electrical gradients and energy from chemical reactions. Ion exchange in cell membranes is responsible for nutrient transport from production sites to where they are broken down to release energy. Sucrose transport is vital for growth in higher plants and recent research has led to the discovery of a class of sugar carriers called SUT4. The SUT4 transporter is a low affinity, high capacity proton-sucrose transporter that participates in long distance sucrose transport in higher plants. We demonstrated the possibility to use purified SUT4 transporter proteins — with the genetic code from Arabidopsis thaliana expressed on yeast cells — for fluid transport driven by pH gradient and from exergonic ATP hydrolysis reaction in the presence of ATP-ase enzyme. The SUT4 proteins were reconstituted on a planar bilayer lipid membrane formed from 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero- 3-Phosphoethanolamine (POPE) phospholipids on a porous substrate. This article builds upon our previous work to harness energy from the ATP-ase reaction using SUT4 to produce a proton current through SUT4 and demonstrates the technical feasibility to generate electrical current in an external circuit. The results from our characterization experiments on a single cell demonstrate that the power source behaves like a constant current power source with an internal resistance of 10-22 kΩ and produces a peak power of 150 nW.

Poly vinylidene fluoride (PVDF) has been widely investigated due to its important pyro- and piezoelectric properties. These properties have found various applications, especially as sensor and actuators. The existence and optimization of these properties is intimately related with the fraction of the polymer in the crystalline phase, its structure, microstructure and orientation. All of these in turn heavily depend on the processing conditions. PVDF is a semi-crystalline polymer which shows polymorphism and is commonly crystallized in non-polar crystalline α-phase. The piezo- and pyroelectric properties mainly depend on the β-phase, so that increasing β-phase content has always been of great concern in this field.

β-phase can be obtained by mechanical stretching of α-phase films at a given temperature or directly from solution. Conversion of α into β-phase takes place at stretching temperatures below 100 °C, at a stretch ratio of about 3–5. Nevertheless the achieved amount of β-phase in the crystalline fraction of the material is never 100%. In the films obtained from solution, 100% beta phase films can be achieved in either a porous or non-porous form. The degree of crystallinity is also larger for the samples obtained from solution.

This work is mainly devoted to the study of the variations in the topological morphology and piezoelectric domain response of PVDF prepared by the aforementioned methods by scanning force microscopy in a piezo-response mode.

We present a modular approach toward poly(vinylidene fluoride) based ferroelectric polymers with high dielectric constants and energy densities. This strategy is based on a two-step reaction including the co-polymerization of vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE) and a subsequent hydrogenation reaction. Due to the similar reactivity of VDF and CTFE in free radical polymerization and quantitative yield of dechlorination reaction, the chemical compositions of the resulting terpolymers can be precisely controlled, leading to tunable Curie temperatures and dielectric constants. A library of the ferroelectric polymers with dielectric constants varying from 11 to 50 measured at 1 kHz and room temperature has been prepared. The structural characteristics including microstructure, chain conformation, and crystallinity of the polymers have been carefully elucidated as a function of the chemical composition by 1H and 19F NMR, Fourier transform infrared spectroscopy, and wide angle X-ray diffraction. The influence of the polymer compositions on thermal transitions and dielectric constants has also been investigated.

The kinetics of the isothermal crystallization from the melt at different crystallisation temperatures and the melting behaviour of Poly(vinylidene fluoride) (PVDF) in the alpha phase has been investigated. The variation of the microstructure of the samples crystallized at different temperatures was monitored with time by Optical Microscopy. The correlation between microstructure and kinetic parameters allows the tailoring of the microstructure by choosing the crystallisation conditions of the samples. Raman and Infrared Transmission Spectroscopy also show the appearance of the γ-phase for higher crystallisation temperatures. The influence of the crystallisation kinetics on the degree of crystallinity of the samples will be also presented and discussed.

After combining the PVDF and BST powders with different particle sizes, the anti-voltage strengths of composites was tested. Although the concentrates of ceramic were all the same, their anti-voltage strengths were distinguished. The results showed that the bigger particles or less thickness of material could benefit to the anti-voltage strength and ultimately enhanced the energy storage density of composites. Moreover, the distribution of particle dimension also influenced the strengths of materials. Composite with homogeneous particles performed higher strength than that of composites with inhomogeneous particles.

A hydrophobic fluoropolymer:BaTiO3 nanocomposite is presented for achieving lower-voltage electrowetting operation. The composite fluoropolymer film exhibits as much as a 10X increase in measured dielectric constant. Increased surface roughness with BaTiO3 content increased the sessile drop contact angle from θ∼104° to 121° with compositions ranging from 0 to 97 vol. % of BaTiO3 in the fluoropolymer. A larger change in electrowetted contact angle is observed for the 50 vol. % of BaTiO3 nanocomposite (delta theta∼60°) compared to a standard fluoropolymer film of 1 um thickness (delta theta∼30°). Furthermore, required operating voltage for electrowetting decreases by ∼30V for films with high BaTiO3 content. Strong charge storage in the nanocomposite was observed via a new bistable electrowetting effect. For samples with strong charge storage, the droplet remains wetted (>2 minutes) even after removing the applied voltage. Rapid (< 1s) droplet de-wetting could be achieved by briefly applying a reverse polarity voltage to remove the stored charge in the nanocomposite.

Very large electro-optic effect has been observed in relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) ( P(VDF-TrFE-CFE) ) terpolymer. By adding small amount of zinc sulfide (ZnS) nanoparticles, the refractive index of the nanocomposites can be tuned between about 1.4 and 1.5 while retaining large electro-optic effect and high transparency. Tunable long-period fiber gratings have been fabricated with the nanocomposite as the second cladding, and over 50nm of resonant wavelength shift has been achieved under a change of electric field of 30V/μm, which is much larger than other reported E-O tuning ranges. This corresponds to a pure refractive index change of the nanocomposite of Δn/n ∼ 0.4%.

Needle-like polyanilines (PANi) were prepared at 15 °C by emulsion polymerization and their conductivities were obtained up to 3 S/cm according to the addition rate of ammonium peroxysulfate (APS) aqueous solutions with reaction conditions of 0.4 to 0.5 APS/aniline ratios and 0.4 to 0.5 M aniline concentrations. Needle-like complexes doped with p-toluenesulfonic acid (pTSA) were prepared with the oxidant solution added so slowly as to be for 3 to 3.6 hours. The high reaction temperatures ranging from 5 to 15 °C was the second condition to have needle-like anilinium complexes polymerized without their breaking during polymerization. A filler shape is one of the most important parameters influencing a percolation concentration of conductive fillers dispersed in a non-conductive matrix. Needle-like polyanilines could be potentially used as conductive fillers to show electromagnetic interference and radar absorption effects.

The effects of structural conformation and order on materials properties and reactivity in thin films of an amphiphilic, regioregular polythiophene π-conjugated polymer (πCP) derivative are presented. Thin films deposited by the Langmuir Blodgett technique provide highly ordered anisotropic films compared to those deposited by spin cast methods. Large differences in both the thermal reactivity and physical properties of the films are observed.

By using conventional solution casting method, a flexible ceramic [CaCu3Ti4O12 (CCTO)]-Polymer [P(VDF-TrFE)] composite has been fabricated. The CCTO ceramic powders with a relative uniform size were prepared by traditional powder processing method. The dielectric properties of these films with different CCTO fractions were determined. The process was optimized to achieve high dielectric constant. A dielectric constant about 510 at room temperature and 1240 at 95 °C at 1 kHz for 6 layer hot compression was obtained.

Poly(chloro-p- Xylene) or Parylene –C thin films are particularly attractive for dielectric as well as biomedical applications. In the current work the dielectric properties of Parylene-C thin films are investigated to form laminar composites with oxide thin films for high energy density pulsed power capacitors. Parylene-C thin films were synthesized by pyrolytic vapor decomposition polymerization of dichloro-di(p-Xylene) monomer. Annealing of films at 225°C has shown to enhance crystallinity of film. Conduction in Parylene-C thin films appears to be bulk-controlled with the hopping charges contributing to leakage current. The barrier height of 0.89eV and hopping distance of 2 - 2.5nm are physically plausible and similar to previously reported values in polymer literature.

The PET/x.PHB samples were polarized at different temperatures (30-250°C) under various biasing fields ranging from 40 to 200 kV/ cm. The TSD currents were obtained at a heating rate of 2 °C/min in the temperature range (15-250)°C. The TSD current spectra in general comprise of three maxima namely β, α and δ in ascending order of temperature. However number of peaks actually appearing in these spectra, their location, height and sharpness are governed by polarization/depolarization parameters as well as the value of ‘x’ in a particular sample. The β peak appearing around (110-140°C) has been recognized as a dipolar relaxation process and is due to PET rich phase. The α- peak (160-180°C) recognized as space charge process is due to PHB rich phase and cold crystallization of PET rich phase. The δ peak (190-210°C) is a melting process due to the movement of large segments leading to Smectic-E like phase. In addition PET/x.PHB also exhibit a weak low temperature dipolar relaxation process β′ peak around (30-40)°C. In the vicinity of α-relaxation a rigid amorphous phase dipolar relaxation process γ relaxation is also observed.

Poly(urea-formaldehyde) capsules enclosing electrophoretic particle dispersion were formed by carrying out an in-situ polymerization reaction in an oil-in-water emulsion. The internal dispersion was composed of pigment particles Yellow-14 modified by charge control agent to have superior electrophoresis velocity and the mixture of tetrachloroethylene and sec-butylbenzene, using Span 80 as the stabilizer and emulsifier. FE-SEM, TEM, and optical microscope (OM) were performed to investigate on the capsule size and surface morphology. Contact angle measurements showed that UF prepolymer deposited at the o/w interface to form hollow capsules only when the interfacial tension is large enough.

P(VDF-CTFE) based nanocomposites were prepared by mixing the polymer with carbon nanotube (CNT) or C60 using solution cast method. The volume fraction of the CNT or C60 was from 0.1 % to 1.0%. The influence of CNT and C60 on the crystallization behavior of P(VDF-CTFE) was determined using XRD and DSC as well as the P-E loop. It is found that the CNT or C60 enhances the β-phase and the crystallinity. The crystallinity process in the composites was studied using DSC.

Low k material with high deterrence ability of copper diffusion has been proposed to reduce the effective electrical resistance of copper wirings. Providing organic low k material with deterrence ability was attempted by adding a chemical agent that chemically combines with copper. The insulation lifetime of the low k film with benzotriazole (BTA) as the copper scavenger was about two orders of magnitude higher than that of BTA-free low k film, at the practical electric field strength of 0.1 MV/cm. The copper diffusion deterrence ability was clearly dependent on the ability of the copper scavenger.

Basic recent results, properties and characteristics of ionic polymer conductor nano-composites (IPCNC) as biomimetic distributed nanosensors, nanoactuators and artificial muscles are briefly discussed in this paper. Some fundamental considerations on biomimetic distributed nanosensing and nanoactuation are first presented and then expanded to cover some recent advances in manufacturing techniques, force optimization, 3-D fabrication of IPMC's, recent modeling and simulations, sensing and transduction and product development. This paper also covers some recent industrial and medical applications including a multi-fingered grippers (macro, micro, nano), biomimetic robotic fish and caudal fin actuators, diaphragm micropump, multi-string musical instruments, linear actuators made with IPMNC's, IPMNC-based data glove and attire, IPMNC-based heart compression/assist devices and systems, wing flapping flying system made with IPMNC's and a host of others.

Permittivity and anti-voltage ability commonly determined the energy storage density of material. Although composite could be molded easier than ceramic, its lower energy storage density prevented the material from application since the polymer usually took on poor dielectric constant. In order to enhance the energy storage performance of composite, PAn was introduced to PVDF by emulsion polymerization. SEM of the co-polymers showed that they could construct continuous media till the concentrate of aniline reached 25% while polymerizing. The permittivity of polymer rose along with the concentrate increasing of aniline and pH falling value of retreating solution. The permittivity and anti-voltage strength of composite also charged correspondingly. As a consequence, the energy storage density innovated much higher than ever. The maximum energy storage density could approach 0.9185Johr/cc.

The paper reported a novel flexible concept for acquiring the fingerprint that based on the piezoelectric PVDF (polyvinylidene fluoride) was integrated into the flexible polyimide substrate to form the fingerprint. In this study, it focused on the array PVDF fabrication and dynamic control circuit to read pressure signal for fingerprint identification. The fabrication of PVDF powder was melt at 180°C, pressed under 2 tons and subsequently quenched at 10°C/min to form the PVDF films. Next the PVDF films were put into the oven at different temperatures for 40 minutes to stretch 4 times from its original length. As for the dynamic control, the sensing circuit was presented two parts, one is charge amplifier and the other is capacitance detect by using frequency oscillator. We demonstrated that the dynamic pressure measurement of PVDF could achieve fingerprint acquisition. Experimental results showed the response speed of sensing is as fast as 5 ms. Therefore, the aim of this study is to speed up the technology for promoting the flexible fingerprint.

A novel plasma co-polymerization technology, using flexibly-mixed molecular gas of 6-membered ring-type vinyl-siloxane and 8-member ring-type one, has been developed for new interlayer dielectric film.