Conducting Polymer Shell Research Articles

(Invited) Energy Transfer in Hybrid Plasmonic Nanostructures

A surface plasmon in a metal nanoparticle is the coherent oscillation of the conduction band electrons leading to both strong absorption and scattering as well as large local electromagnetic fields. Plasmonic nanoparticles therefore have the potential to induce electronic transitions in nearby materials. However, but fast internal relaxation limits the efficiency of such plasmonic mediated processes. In this talk, I will discuss our recent results of a new type of nanomaterial: hybrid nanoantennas comprised of plasmonic nanorods with photoconductive polymer coatings that were grown by photo-electrochemistry. The formation of the conductive polymer shell is selective to the nanorods, while the polymerization is enhanced by photoexcitation. In situ single pareticle dark-field scattering spectroscopy and simulations support an energy transfer mechanism with up to 50% efficiency. These hybrid nanoantennas combine the unmatched light harvesting properties of a plasmonic nanoparticles with the similarly unmatched device processability of polymersl.

Conducting polymer engineered covalent organic framework as a novel electrochemical amplifier for ultrasensitive detection of acetaminophen

Two-dimensional covalent organic framework (COF) has distinctive properties that offer potential opportunities for developing advanced electrode materials. In this work, a core-shell material composed of TAPB-DMTP-COF (TAPB, 1,3,5-tris(4-aminophenyl)benzene; DMTP, 2,5-dimethoxyterephaldehyde) core and conducting polymer shell, TAPB-DMTP-COF@PANI, was synthesized solvothermally using a polymerization method. The structural characteristics of the prepared composite were revealed by X-ray diffraction patterns (XRD), fourier transform infrared spectra (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM). The electrochemical analyses were verified by subsequent monitoring of trace levels of acetaminophen. This resultant composite not only facilitated acetaminophen to interact with absorption sites by π-π stacking effect and hydrogen bonding but also overcame the poor conductivity of COF. Under the optimal conditions, a low limit of detection of 0.032 μmol/L and wide linear range of 0.10−500 μmol/L were obtained. The electrochemical platform was almost unaffected by other interfering substances, and successfully applied for the practical detection of acetaminophen in commercial tablet, human blood serum and urine. The enhanced performance makes this COF based core-shell composite a promising material in electrochemical sensor.

Influence of electric field strength on the rheological behavior of electro-rheological fluid based on poly(o-toluidine)-coated silica

A poly(o-toluidine)-decorated rice husk silica-based bio-composite was prepared and utilized as the dispersion phase for an electro-rheological fluid. The surface of silica particles was grafted with a silane coupling agent before coating with the conductive polymer shell. The characteristics of the silica, modified silica, and core-shell structured particles were confirmed via scanning electron microscopy, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and transmittance electron microscopy. The rheological properties of the electro-rheological fluid under various external field strengths were studied in detail using rotational rheometry. The data indicated that the rheological fluids exhibited high performance with a high polarized rate under an external field and are environmentally benign.

Poly(p‐phenylenediamine)‐coated magnetic particles: Preparation and electrochemical properties

Magnetic particles are of great interest in various biomedical applications, such as, sample preparation, in vitro biomedical diagnosis, and therapy. For biosensing applications, the used functional magnetic particles should answer numerous criteria such as; submicron size in order to avoid rapid sedimentation, high magnetic content for fast separations under applied magnetic field, and finally, good colloidal stability. Therefore, the aim of this work was to prepare submicron magnetic core and conducting polymer shell particles. The polymer shell was induced using p‐phenylenediamine as key monomer. The obtained core–shell particles were characterized in terms of particle size, size distribution, magnetization properties, Fourier transform infrared (FTIR) analysis, surface morphology, chemical composition, cyclic voltammetry, and impedance spectroscopy. The best experimental condition was found using 40 mg of povidone (PVP—stabilizing agent) and 0.16 mmol of p‐phenylenediamine. Using such initial composition, the core‐shell magnetic nanoparticles shown a narrowed size distribution around 290 nm and high magnetic content (above 50%). The obtained amino containing submicron highly magnetic particles were found to be a conducting material and superparamagnetic in nature. These promising conducting magnetic particles can be used for both transport and lab‐on‐a‐chip detection.

Exploring hydrogen molybdenum bronze for sodium ion storage: Performance enhancement by vertical graphene core and conductive polymer shell

Rational construction of high-performance electrode materials is crucial for advancement of sodium ion batteries (SIBs). In this work, for the first time, we explore the sodium ion storage performance of hydrogen molybdenum bronze (HMB). To perfect its performance, we controllably sandwich HMB into conductive vertical graphene (VG) skeleton and poly(3,4-ethylenedioxythiophene) shell forming free-standing VG/HMB/PEDOT composite arrays with the help of powerful successive electrodeposition methods. HMB is completely compatible with VG and PEDOT, and intimately combined with them. Due to the unique integrated porous structure and omnibearing conductive network, the designed VG/HMB/PEDOT composite arrays show high sodium ion storage capacities (385mAhg−1 at 200mAg−1) and superior long-term cycling stability (320mAhg−1 at 200mAg−1 after 500 cycles) when used as anode of SIBs, much better than the VG/HMB and HMB/PEDOT counterparts. Our proposed fabrication strategy offers a new route for designing high-performance electrodes for applications in electrochemical energy storage and electrocatalysis.

Electrically-responsive core-shell hybrid microfibers for controlled drug release and cell culture.

Fiber-shaped biomaterials are useful in creating various functional objects from one dimensional to three-dimensional. The fabrication of microfibers with integrated physicochemical properties and bio-performance has drawn an increasing attention on researchers from chemical to biomedical. This study combined biocompatible bacterial cellulose with electroconductive poly(3,4-ethylenedioxythiophene) and further reduced them to a highly electroactive BC/PEDOT core-shell microfiber electrode for electrochemical actuator design. The result showed that the microfibers were well fabricated and the release of drugs from the microfibers was enhanced and could be controlled under electrical stimulation externally. Considering the excellent biocompatibility and electroactive toward PC12 cells, these microfibers may find use as templates for the reconstruction of fiber-shaped functional tissues that mimic muscle fibers, blood vessels or nerve networks in vivo.

A core-shell titanium dioxide polyaniline nanocomposite for the needle-trap extraction of volatile organic compounds in urine samples.

We synthesized a titanium dioxide-polyaniline core-shell nanocomposite and implemented it as an efficient sorbent for the needle-trap extraction of some volatile organic compounds from urine samples. Polyaniline was synthesized, in the form of the emeraldine base, dissolved in dimethyl acetamide followed by diluting with water at pH 2.8, using the interfacial polymerization method. The TiO2 nanoparticles were encapsulated inside the conducting polymer shell, by adapting the in situ dispersing approach. The surface characteristics of the nanocomposite were investigated by Fourier transform infrared spectrometry, scanning electron microscopy, and transmission electron microscopy. After obtaining acceptable preliminary results, some selected volatile compounds, including chloroform, benzene, toluene, ethylbenzene, xylene, and chlorobenzenes were used as model analytes to validate the enrichment properties of the prepared sorbent in conjunction with gas chromatography mass spectrometric detection. Important parameters influencing the extraction process such as extraction temperature, ionic strength, sampling flow rate, extraction time, desorption temperature, and time were optimized. The limits of detection and limits of quantification values were in the range of 0.5-3 and 2-5ng/L, respectively, using time-scheduled selected ion monitoring mode. The relative standard deviation percent with three replicates was in the range of 5-10%. The applicability of the developed needle-trap method was examined by analyzing urine samples and the relative recovery percentages for the spiked samples were in the range of 81-105%.

Facile fabrication of flexible core–shell graphene/conducting polymer microfibers for fibriform supercapacitors

We fabricated graphene core conductive polymer (PEDOT) shell fibers (GF@PEDOT). The unique cloth-like structure enabled the graphene fibers excellent electrochemical performance and greatly enhanced the flexibility.

Viral-templated gold/polypyrrole nanopeapods for an ammonia gas sensor

One-dimensional gold/polypyrrole (Au/PPy) nanopeapods were fabricated using a viral template: M13 bacteriophage. The genetically modified filamentous virus displayed gold-binding peptides along its length, allowing selective attachment of gold nanoparticles (Au NPs) under ambient conditions. A PPy shell was electropolymerized on the viral-templated Au NP chains forming nanopeapod structures. The PPy shell morphology and thickness were controlled through electrodeposition potential and time, resulting in an ultra-thin conductive polymer shell of 17.4 ± 3.3 nm. A post-electrodeposition acid treatment was used to modify the electrical properties of these hybrid materials. The electrical resistance of the nanopeapods was monitored at each assembly step. Chemiresistive ammonia (NH3) gas sensors were developed from networks of the hybrid Au/PPy nanostructures. Room temperature sensing performance was evaluated from 5 to 50 ppmv and a mixture of reversible and irreversible chemiresistive behavior was observed. A sensitivity of 0.30%/ppmv was found for NH3 concentrations of 10 ppmv or less, and a lowest detection limit (LDL) of 0.007 ppmv was calculated. Furthermore, acid-treated devices exhibited an enhanced sensitivity of 1.26%/ppmv within the same concentration range and a calculated LDL of 0.005 ppmv.

Submicron magnetic core conducting polypyrrole polymer shell: Preparation and characterization

Magnetic particles are of great interest in various biomedical applications, such as, sample preparation, in vitro biomedical diagnosis, and both in vivo diagnosis and therapy. For in vitro applications and especially in labs-on-a-chip, microfluidics, microsystems, or biosensors, the needed magnetic dispersion should answer various criteria, for instance, submicron size in order to avoid a rapid sedimentation rate, fast separations under an applied magnetic field, and appreciable colloidal stability (stable dispersion under shearing process). Then, the aim of this work was to prepare highly magnetic particles with a magnetic core and conducting polymer shell particles in order to be used not only as a carrier, but also for the in vitro detection step. The prepared magnetic seed dispersions were functionalized using pyrrole and pyrrole-2-carboxylic acid. The obtained core–shell particles were characterized in terms of particle size, size distribution, magnetization properties, FTIR analysis, surface morphology, chemical composition, and finally, the conducting property of those particles were evaluated by cyclic voltammetry. The obtained functional submicron highly magnetic particles are found to be conducting material bearing function carboxylic group on the surface. These promising conducting magnetic particles can be used for both transport and lab-on-a-chip detection.

Stably Doped Conducting Polymer Nanoshells by Surface Initiated Polymerization.

Despite broad applications ranging from electronics to biomedical sensing and imaging, a long-standing problem of conducting polymers is the poor resistance to dedoping, which directly affects their signature electrical and optical properties. This problem is particularly significant for biomedical uses because of fast leaching of dopant ions in physiological environments. Here, we describe a new approach to engineer multimodal core-shell nanoparticles with a stably doped conductive polymer shell in biological environments. It was achieved by making a densely packed polymer brush rather than changing its molecular structure. Polyaniline (PANI) was used as a model compound due to its concentrated near-infrared (NIR) absorption. It was grafted onto a magnetic nanoparticle via a polydopamine intermediate layer. Remarkably, at pH 7 its conductivity is ca. 2000× higher than conventional PANI nanoshells. Similarly, its NIR absorption is enhanced by 2 orders of magnitude, ideal for photothermal imaging and therapy. Another surprising finding is its nonfouling property, even outperforming polyethylene glycol. This platform technology is also expected to open exciting opportunities in engineering stable conductive materials for electronics, imaging, and sensing.

Sulfur quantum dots wrapped by conductive polymer shell with internal void spaces for high-performance lithium–sulfur batteries

Novel core–shell sulfur quantum dots/PVK nanocomposites were synthesized by a facile two-step dissolution–precipitation method.

Ultrafine Sulfur Nanoparticles in Conducting Polymer Shell as Cathode Materials for High Performance Lithium/Sulfur Batteries

We report the synthesis of ultrafine S nanoparticles with diameter 10 ~ 20 nm via a membrane-assisted precipitation technique. The S nanoparticles were then coated with conducting poly (3,4-ethylenedioxythiophene) (PEDOT) to form S/PEDOT core/shell nanoparticles. The ultrasmall size of S nanoparticles facilitates the electrical conduction and improves sulfur utilization. The encapsulation of conducting PEDOT shell restricts the polysulfides diffusion, alleviates self-discharging and the shuttle effect, and thus enhances the cycling stability. The resulting S/PEDOT core/shell nanoparticles show initial discharge capacity of 1117 mAh g−1 and a stable capacity of 930 mAh g−1 after 50 cycles.

Solution Processed TiO2 Nanotubular Core with Polypyrrole Conducting Polymer Shell Structures for Supercapacitor Energy Storage Devices

ABSTRACTOrdered one dimensional polypyrrole conducting polymer structure as a shell over TiO2 nanotube arrays at the core were formed by pulsed current electropolymerization. TiO2 nanotubes with rippled wall structure are designed by action of water in the anodizing medium. This provides open tube structure supporting short diffusion length and increased accessibility of ions involved in redox transition for energy storage. Electrochemical properties evaluated by cyclic voltammetry and electrochemical impedance spectroscopy show specific capacitance of 34-44 mF.cm-2 and extremely low bulk and charge transfer resistances.

Au/Au@Polythiophene Core/Shell Nanospheres for Heterogeneous Catalysis of Nitroarenes

Monodisperse Au/Au@polythiophene core/shell nanospheres were facilely prepared through the reduction of gold precursor, AuCl₄⁻, by 2-thiopheneacetonitrile in an aqueous solution. Concomitantly, 2-thiopheneacetonitrile polymerized during this redox process. As a result, Au nanoparticle was encapsulated by conductive polymer shell to afford novel core/shell nanospheres. Interestingly, the shell was composed of very tiny Au nanoparticles surrounded with thiophene polymers. Thus, the new material is best described as Au/Au@polythiophene core/shell nanospheres. FT-IR spectroscopy revealed that the Au nanoparticles were coordinated by the C≡N groups of the polythiophene shell. Some of the C≡N groups were partially hydrolyzed into COOH groups during the redox process because of the acidic reaction condition. The shell was conductive based on the typical ohmic behavior found in electrical measurement. The Au/Au@polythiophene core/shell nanospheres were found to be very active catalysts for the hydrogenation of various nitroarene compounds into corresponding aminoarene compounds in the presence of NaBH₄. Both hydrophilic and hydrophobic nitroarenes were efficiently hydrogenated under mild conditions.

Dielectric behaviour of nano-crystalline spinel Ni0·2Ca0·8Fe2O4 and their nano-composite with polypyrrole

The spinel ferrite nano-particles of chemical composition Ni0·2Ca0·8Fe2O4 have been prepared by sol-gel method. Subsequently, the nanoparticles are encapsulated with the intrinsically conducting polymer shell of polypyrrole. The X-ray diffraction patterns confirm the single phase cubic spinel structure of the materials. To understand the dielectric properties of the materials, frequency-dependent dielectric measurement has been performed at 300 K in the range of 100 mHz to 2 MHz. On polymerization, both the dielectric strength as well the dielectric loss is significantly increased. Also, the dielectric conductivity, which arises from the electron hopping mechanism, is considerably increased on polymerization.

A versatile surfactant-mediated synthetic route to gold/polyaniline derivative core/shell nanocomposites

This article describes a versatile two-step method for gold/polyaniline derivative core/shell nanocomposites with the aid of nonionic surfactant F127. First, F127 and monomer were introduced to gold colloids followed by the addition of oxidant to initiate the polymerization of monomer to afford a conducting polymer shell around each gold nanoparticle. Experimental parameters, such as kinds and concentrations of surfactant and monomer, gold core size and shape, reaction time, were systematically investigated to disclose the underground mechanisms involved in the formation of gold/polymer core/shell nanocomposites. Furthermore, Fourier transform infrared, ultraviolet–visible, X-ray diffraction, and X-ray photoelectron spectroscopy techniques were used to characterize the gold/polymer core/shell nanocomposites. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3903–3912, 2010

CoFe2O4–polypyrrole (PPy) nanocomposites: new multifunctional materials

Spinel ferrites (iron cobalt oxide) were prepared by the microemulsion method atdifferent temperatures and sodium dodecyl sulphate (SDS) surfactant concentrations.Subsequently, a quantity of the different samples were coated with an intrinsicallyconducting polymer (ICP) shell of polypyrrole. The polymer shell was synthesized by achemical route after the ferrites particle production. By combining in a singlematerial the electrical conductivity of ICPs and the magnetic properties ofnanopowder ferrites, new multifunctional materials have been developed. DifferentCoFe2O4 grain size particles were obtained ranging from 3 to 30 nm, as determined byx-ray diffraction (XRD). Particles with grain size below a critical size exhibit asuperparamagnetic behaviour. These superparamagnetic particles, withoutand with a conducting polymer shell, were analysed by transmission electronmicroscopy (TEM) to find the grains’ morphology and the growth evolution ofthe polypyrrole shell in the ferrites grains. The electrical conductivity of thenanocomposite was measured by the four points probe method, showing values of120 ± 4 S cm−1 at ambient temperature. The behaviour of the magnetization and the coercivity withtemperature, from nearly 0 K to the ambient, were measured in a vibrating samplemagnetometer (VSM).

The Organic/Inorganic Interface in Micro and Nano Composite Materials

ABSTRACTWe report the synthesis of new inorganic/organic composite particles with a core/shell structure. The core component is an inorganic oxide (e.g. TiO2, CeO2 or MoO3), and the shell component is a double-strand polyaniline. Three methods for material synthesis were examined. The electrochemical properties of one type of the composite particles show electronic interaction between the organic conducting polymer shell and its inorganic core. The double-strand polyaniline in the composite shows better pH stability of the conductive form than that of the corresponding single-strand polyaniline in a similar core/shell composite.

A Variational Solution of the Thermoelectric Transport Properties of Two-Component Nanocomposite Systems

ABSTRACTThe successful fabrication of a nanocomposite in bulk form consisting of a randomly oriented assembly of nanoscale sized core-shell particles has required an increased understanding of the theoretical aspects of the thermoelectric transport properties. Our particular nanocomposite consists of a nanorod core in 1D quantum confinement coated with an outer conducting polymer shell. Upon fabrication of the bulk composite, these nanorods are embedded within a three-dimensional conducting polymer matrix. We address the nanorod thermoelectric components by assuming a single parabolic band within the one-dimension density of states. Both elastic and inelastic scattering of electrons or holes is accommodated by solving the variational form of the Boltzmann transport equation. An altered lattice thermal conductivity for the confined nanorods is calculated separately to account for boundary scattering that is important in low dimension structures. Exact expressions for the bulk effective electrical and thermal conductivities, Seebeck coefficient and figure of merit are then obtained through the field decoupling transformation, which is a special case of two-component composites. Our method is easily generalized to any two component composite of spherical or cylindrical microstructure and is independent of the materials bulk geometry. The results similarly apply to one, two or three dimensional transport regimes with or without quantum confinement merely by solving the appropriate fundamental transport equations for each constituent material. Comparison to experimental data is then presented which helps validate the nanocomposite theory.