Polyaniline Shell Research Articles

Fabrication of novel polyaniline/flowerlike copper monosulfide composites with enhanced electromagnetic interference shielding effectiveness

ABSTRACTNovel polyaniline (PANI)/flowerlike CuS composites with improved electromagnetic interference (EMI) shielding effectiveness (SE) were prepared through the in situ polymerization of PANI into the flowerlike CuS microspheres. X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet–visible optical absorption spectroscopy, thermogravimetric analysis, electrical conductivity testing, and EMI SE testing were used to characterize the as‐obtained products. The results reveal that the flowerlike CuS was uniformly coated by a PANI shell. Most importantly, compared with the original CuS and pure PANI, the novel PANI/flowerlike CuS composites exhibited a remarkably enhanced SE. With a thickness of 3 mm, the optimal EMI SE of the PANI–CuS composites reached −45.2 dB at 2.78 GHz, and an improved shielding efficiency below −18 dB was also obtained over the frequency range from 300 kHz to 3 GHz. This suggested that these novel PANI/flowerlike CuS composites have promising applications in the field of shielding materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45232.

Synthesis of polyaniline shell on nickel oxide nanoflake arrays for enhanced lithium ion storage

Developing conducting polymer/oxide composites are of great importance to construct advanced electrochemical devices. In this work, we report a successive electrodeposition methods to fabricate polyaniline (PANI) on nickel oxide (NiO) nanoflake forming composite core-shell arrays. A thin layer of PANI of ∼10nm is successfully coated on the surface of NiO nanoflake core. High porosity and enhanced conductivity are obtained in this composite electrode. As anode materials for lithium ion batteries, the NiO/PANI core-shell arrays exhibit weaker polarization and better cycling performance as compared to the bare NiO film. The second discharge capacity of NiO/PANI composite arrays is about 780mAhg−1 at 0.1Ag−1, higher than that of the bare NiO film (679mAhg−1). The improvements of the electrochemical properties are attributed to the PANI, which forms a uniform conductive network leading to improved electrochemical performance.

Preparation, morphology and thermal properties of microencapsulated palmitic acid phase change material with polyaniline shells

Novel microencapsulated phase change materials (MicroPCMs) in which palmitic acid (PA) acted as core material and polyaniline as shell material were prepared by in situ polymerization method without any emulsifier and doping agent. The effects of the preparation temperature, polymerization time, oxidant concentration and the acid dopants on the morphology and thermal properties of the MicroPCMs were investigated by field emission scanning electron microscope, differential scanning calorimetry and thermogravimetry. The results showed that spherical MicroPCMs could be obtained when the polymerization was initiated at a temperature higher than the melting point of PA with a medium oxidant concentration and then relatively slowly completed the polymerization at a low temperature without any acid dopant. The best preparation condition in this work was that the polymerization was initiated at 348 K for 2 h with the oxidant/aniline mole ratio of 0.75 and then completed at 303 K for 18 h. The prepared MicroPCMs showed spherical morphology with the phase change enthalpy of 106.3 J g−1. Furthermore, the evaporation of PA in the MicroPCMs was postponed due to that PA was fully encapsulated in the capsules, which is favorable for its application.

Anticorrosion pigments with a shell of doped polyaniline

It has been determined that a dopant acid affects the dispersion composition of the prepared coreshell pigments. Anticorrosion properties of the pigments with the polyaniline (PAN) shell have been investigated. Pigments with a PAN shell doped by phosphoric acid possess the highest anticorrosion properties. The dependence of the electrical conductivity on the substrate-to-PAN ratio has been determined. Anticorrosion properties of polymer coatings containing the pigments with PAN shell have been studied.

Three-dimensional, free-standing polyaniline/carbon nanotube composite-based electrode for high-performance supercapacitors

Vertically aligned Carbon Nanotube (CNT) arrays are synthesized directly on CNT sheets used as substrates by plasma enhanced chemical vapor deposition (PECVD) in NH3 plasma environment. The resulting 3-D nanostructured, N-doped CNT (NCNT) architecture combines high conductivity and superior mechanical properties of CNT sheets with porous structure and high electrochemical activity of CNT arrays. NCNT sheets are then used as scaffolds for polyaniline (PANI) deposited by electrodeposition. PANI coating thickness is optimized to create a core-shell morphology with PANI shell supported by CNT core. Freestanding and flexible PANI/NCNT electrodes are fabricated without using any metal supports/foil or binders with the CNT sheets serving as current collectors. PANI/NCNT electrodes with 56 wt% polymer content demonstrate a gravimetric capacitance of 359 F/g at a current density of 1.56 mA/cm2. The electrode also shows high rate capabilities and retains 82% of original capacitance after current density is increased 30-fold to 46.87 mA/cm2. PANI/NCNT electrodes are used to assemble a symmetric supercapacitor device with PVA/H2SO4 hydrogel as separator and electrolyte. The flexible PANI/NCNT supercapacitor showed a specific capacitance of 128 F/g at 2.47 A/g current density and retained over 92% of initial capacitance after 10000 cycles of charge-discharge at 24.7 A/g current density.

A triple-synergistic strategy for combinational photo/radiotherapy and multi-modality imaging based on hyaluronic acid-hybridized polyaniline-coated WS2 nanodots.

In this study, we report a strategy for integrating hyaluronic acid (HA), polyaniline (PANI), WS2 nanodots (WS2), and chlorin e6 (Ce6) into a single nanoplatform (HA-WS2@PANI/Ce6) for fluorescence, photoacoustic, and computed tomography multi-modality imaging-guided trimodal photothermal/radiation/photodynamic combination therapy of tumors. The WS2 nanodot core is used as the radiosensitizer with the PANI shell as the hyperthermal agent and the photosensitizer reservoir. HA and Ce6 were adsorbed on the outer shell for tumor targeting and photodynamic therapy, respectively. The in vivo trimodal imaging uncovered that HA-WS2@PANI/Ce6 nanoparticles showed enhanced tumor uptake and diagnosis effects after intravenous injection. More importantly, in the in vitro and in vivo experiments, the nanoparticles exhibited an evident near-infrared induced photothermal effect, which remarkably improved the radiation and photodynamic therapy efficiency by accelerating the blood flow and subsequently increasing oxygen supply in the tumor. The nanohybrids were found to be safe to cells in vitro and organs in vivo. Taken together, our current work demonstrates a nanoplatform for multimodal imaging guided targeted triple-therapy, which reveals a potential strategy for tumor treatment.

A Novel Polyaniline-Coated Bagasse Fiber Composite with Core-Shell Heterostructure Provides Effective Electromagnetic Shielding Performance.

A facile route was proposed to synthesize polyaniline (PANI) uniformly deposited on bagasse fiber (BF) via a one-step in situ polymerization of aniline in the dispersed system of BF. Correlations between the structural, electrical, and electromagnetic properties were extensively investigated. Scanning electron microscopy images confirm that the PANI was coated dominantly on the BF surface, indicating that the as-prepared BF/PANI composite adopted the natural and inexpensive BF as its core and the PANI as the shell. Fourier transform infrared spectra suggest significant interactions between the BF and PANI shell, and a high degree of doping in the PANI shell was achieved. X-ray diffraction results reveal that the crystallization of the PANI shell was improved. The dielectric behaviors are analyzed with respect to dielectric constant, loss tangent, and Cole-Cole plots. The BF/PANI composite exhibits superior electrical conductivity (2.01 ± 0.29 S·cm-1), which is higher than that of the pristine PANI with 1.35 ± 0.15 S·cm-1. The complex permittivity, electromagnetic interference (EMI), shielding effectiveness (SE) values, and attenuation constants of the BF/PANI composite were larger than those of the pristine PANI. The EMI shielding mechanisms of the composite were experimentally and theoretically analyzed. The absorption-dominated total EMI SE of 28.8 dB at a thickness of 0.4 mm indicates the usefulness of the composite for electromagnetic shielding. Moreover, detailed comparison of electrical and EMI shielding properties with respect to the BF/PANI, dedoped BF/PANI composite, and the pristine PANI indicate that the enhancement of electromagnetic properties for the BF/PANI composite was due to the improved conductivity and the core-shell architecture. Thus, the composite has potential commercial applications for high-performance electromagnetic shielding materials and also could be used as a conductive filler to endow polymers with electromagnetic shielding ability.

Synthesis and properties of latex particles with polyaniline shells

Core–shell polyaniline–latex particles have been obtained via oxidative polymerization of aniline hydrochloride in the presence of charged polystyrene latex. The polymerization conditions have been determined under which polyaniline is predominantly formed on the surface of latex particles to yield closed shells. The dependence of the electrical conductivity of the resulting particles on the initial concentration of aniline hydrochloride in the polymerization medium has been studied. Stable aqueous dispersions of polyaniline–latex particles have been prepared by modifying the particles with sodium 3-mercaptopropane sulfonate.

Dual-Responsive Reversible Plasmonic Behavior of Core–Shell Nanostructures with pH-Sensitive and Electroactive Polymer Shells

We report novel dual-responsive plasmonic core–shell anisotropic nanostructures composed of gold nanorod (AuNR) and responsive polyaniline (PANI) shells with plasmonic mode appearance reversibly modulated through orthogonal stimuli (i.e., electrical potential and pH change). In this system, the PANI shells provide AuNR cores with three different refractive index environments depending on stimuli (pH and electrical potential). Therefore, no additional secondary responsive component is necessary to induce the dual-responsive properties of AuNR cores. Furthermore, in this study, dual-responsive properties can be realized for nanostructures fixed on substrates, whereas previously reported dual-responsive plasmonic systems can only be controlled in solution. Here, the highest localized surface plasmonic resonance (LSPR) shift of the AuNR cores can be induced by changing both local pH and applying electric potential. Notably, a significant plasmon band shift by 107 nm is realized with only 8 nm thick PANI shell...

Yolk-Shell Nanocomposites of a Gold Nanocore Encapsulated in an Electroactive Polyaniline Shell for Catalytic Aerobic Oxidation.

Noble metal nanoparticles (NPs) have been widely applied in nanocatalysis owing to the benefits associated with their miniature size. However, improving their stability and reusability during catalytic applications still remains a great challenge. To this end, monodispersed gold@void@polyaniline yolk–shell nanocomposites (Au@void@PANI YSNs) were synthesized using bottom-up template-assisted methods. Au@SiO2 NPs, prepared from a modified sol–gel process, were used as templates for the thiol–ene click reaction with 4-vinylaniline (VAn) to immobilize the aniline moieties, which later performed as the initiation sites for the oxidative copolymerization of aniline from the outer surface of the Au@SiO2–VAn NPs with an electroactive PANI shell (Au@SiO2@PANI NPs). The silica layer sandwiched between the Au core and PANI shell was selectively removed by aqueous hydrofluoric acid to produce Au@void@PANI YSNs with a movable Au core. The electroactive PANI shell not only serves as a physical barrier that prevents the self-association of Au cores and provides a vacant cavity where chemical transformations take place on the Au cores in a controlled manner but also improves the activity and stability of Au cores due to the electrons delocalization and transfer from the Au d orbitals of the nanocores to the π-conjugated ligands of the PANI shell, as proved by the X-ray photoelectron spectroscopy results. The as-synthesized YSNs were found to perform as flexible and reusable heterogeneous catalysts with high catalytic efficiency for the aerobic oxidation of alcohol in aqueous solution. One may find the present study to be a general and effective way to fabricate monodispersed hollow nanomaterials in a controlled and green manner.

Electrically Controlled Plasmonic Behavior of Gold Nanocube@Polyaniline Nanostructures: Transparent Plasmonic Aggregates

We demonstrate the electrically controlled and reversible plasmonic signature of hybrid polymer–metal nanostructures composed of core/shell nanostructures: gold nanocubes (AuNCs) coated with electrochromic polyaniline (PANI) shells. A reversible tuning of the localized surface plasmon resonance (LSPR) peak of the AuNC core was obtained by applying an electrical potential that caused a reversible oxidation state change in the electroactive PANI nanoshell. A significant shift of the main LSPR peak was achieved with high reversibility and electrochemical stability due to the interplay of the local decay of the electromagnetic field and the controlled thickness of the surrounding polymer shell. Here, the PANI shell acts as an electroactive medium as well as a physical spacer to prevent uncontrollable plasmonic coupling. The most efficient LSPR shift can be induced by the refractive index change of nanoscale PANI shell thickness lower than the electromagnetic field decay length of the given gold nanoparticles....

Magnetoconductive maghemite core/polyaniline shell nanoparticles: Physico-chemical and biological assessment

Nanoparticles of various compositions are increasingly being used in many areas of medicine. The aim of this study was to develop nanoparticles, which would possess both magnetic and conductive properties and, thus improve their suitability for a wider range of biomedical applications. Namely, it would enable both the particle manipulation and imaging using their magnetic properties and simultaneous stimulation of electro-sensitive cell types using their magnetic properties, which can be used in tissue therapy, engineering and as biosensors. Maghemite (γ-Fe2O3) particles were prepared by the co-precipitation of Fe2+ and Fe3+ salts with ammonium hydroxide, followed by the controlled oxidation with NaOCl. The polyaniline (PANI) shell on the γ-Fe2O3 nanoparticles was obtained by the polymerization of aniline hydrochloride with ammonium peroxydisulfate in an aqueous solution of poly(N-vinylpyrrolidone) at two reaction temperatures (0 and 25°C). The resulting γ-Fe2O3&PANI particles were characterized by both the light and transmission electron microscopies, dynamic light scattering, magnetic measurements, UV–vis and energy dispersive X-ray (EDAX) spectroscopy. The size of the starting γ-Fe2O3 particles was 11nm, that increased to 25nm after the modification with PANI. The incubation of both the γ-Fe2O3 and γ-Fe2O3&PANI nanoparticles with the human neuroblastoma derived SH-SY5Y cells for 8 days showed neither significant decrease in the cell viability, nor detectable changes in the cell morphology. This indicates, that the particles have no detectable cytotoxicity in cell culture and represent a promising tool for further use in biomedical applications.

Fabrication of Graphene and AuNP Core Polyaniline Shell Nanocomposites as Multifunctional Theranostic Platforms for SERS Real-time Monitoring and Chemo-photothermal Therapy.

In this work, novel theranostic platforms based on graphene oxide and AuNP core polyaniline shell (GO-Au@PANI) nanocomposites are fabricated for simultaneous SERS imaging and chemo-photothermal therapy. PANI, a new NIR photothermal therapy agent with strong NIR absorption, outstanding stability and low cytotoxicity is decorated on AuNPs by one-pot oxidative polymerization, then the Au@PANI core-shell nanoparticles are attached to the graphene oxide (GO) sheet via π-π stacking and electrostatic interaction. The obtained GO-Au@PANI nanohybirds exhibit excellent NIR photothermal transduction efficiency and ultrahigh drug-loading capacity. The nanocomposites can also serve as novel NIR SERS probes utilizing the intense SERS signals of PANI. Rapid SERS imaging of cancer cells is achieved using this ultrasensitive nanoprobe. GO-Au@PANI also reveals good capability of drug delivery with the DOX-loading efficiency of 189.2% and sensitive NIR/pH-responsive DOX release. The intracellular real-time drug release dynamics from the nanocomposites is monitored by SERS-fluorescence dual mode imaging. Finally, chemo-photothermal ablation of cancer cells is carried out in vitro and in vivo using GO-Au@PANI as high-performance chemo-photothermal therapeutic nanoagent. The theranostic applications of GO-Au@PANI endow it with great potential for personalized and precise cancer medicine.

Evolution and Interdependence of Structure and Properties of Nanocomposites of Multiwall Carbon Nanotubes with Polyaniline

Structure–property relationships of nanocomposites of multiwall carbon nanotubes (MWCNTs) and polyaniline (PANI) doped with dodecylbenzenesulfonic acid (DBSA) are studied and discussed in terms of contribution of the PANI phase properties. Two phases of PANI-DBSA with different properties, such as a shell-wrapping carbon nanotube and separate neat PANI-DBSA domains, are revealed for the first time in the nanocomposites with a high or medium PANI-DBSA content. In the nanocomposites with lower PANI-DBSA contents (<40 wt %), only a core–shell morphology with ∼3 nm or lower thickness PANI shell on the nanotubes is observed. Under this condition, the degree of crystallinity of the PANI-DBSA shell increases almost 2-fold, and thermal stability of the nanocomposite grows sharply. As compared with the neat PANI-DBSA, this special PANI shell phase has more perfect molecular structure and is characterized by a reduced amount of DBSA. It is found that the latter is caused by a competition between the processes of doping of the formed PANI in the shell by the protonic acid and p-doping caused by the MWCNT surface. The nanocomposites demonstrate ppm/ppb range sensitivity to ammonia/methylamine gases with response times, which inversely depend on the PANI-DBSA contents and thickness of the shell.

Highly Enhanced Fluorescence of CdSeTe Quantum Dots Coated with Polyanilines via In-Situ Polymerization and Cell Imaging Application.

The polyaniline (PAN)-coated CdSeTe quantum dots (QDs) were prepared by in situ polymerization of aniline on the surface of CdSeTe QDs. The PAN-coated CdSeTe QDs has a tremendously enhanced fluorescence (∼40 times) and improved biocompatibility compared to the uncoated CdSeTe QDs. The fluorescence intensity of the PAN-coated CdSeTe QDs can be adjusted by controlling the construction parameters of the PAN shell. The kinetics of the in situ controllable polymerization process was studied by varying the temperature, and the apparent activation energy of polymerization was estimated. With the same method, a series of the PAN derivatives were also tested to coat the CdSeTe QDs in this study. All the QDs showed a significant enhancement of the fluorescence intensity and better biocompatibility. The significantly enhanced fluorescence can provide highly amplified signal for luminescence-based cell imaging.

Facile synthesis of NiCo2O4@Polyaniline core-shell nanocomposite for sensitive determination of glucose.

In this work, the core-shell structure of NiCo2O4@Polyaniline (NiCo2O4@PANI) nanocomposite is fabricated via a facile hydrothermal treatment followed by a post-Polyaniline (PANI) coating process. The synthesized materials are characterized by Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectrometer. The biosensing properties of NiCo2O4@PANI composite and NiCo2O4 nanoparticles toward glucose are studied based on glassy carbon electrode. Electrochemical studies indicate that the obtained core-shell NiCo2O4@PANI composite shows higher electrocatalytic activity toward the oxidation of glucose, compared with NiCo2O4 nanoparticles. The enhanced performance is related to the core-shell structure of NiCo2O4@PANI composite and the outstanding conductivity of the polyaniline shell. At a potential of +0.5V, the NiCo2O4@PANI nanocomposite modified glass carbon electrode demonstrates a wide linear range up to 4.7350mM with sensitivity of 4.55mAmM(-1)cm(-2) and detection limit of 0.3833μM. It also shows significant electrochemical stability, good reproducibility and excellent selectivity. The results suggest that the NiCo2O4@PANI nanocomposite is a promising electrode material for electrochemical biosensor.

Fabrication and characterization of stearic acid/polyaniline composite with electrical conductivity as phase change materials for thermal energy storage

This paper presents the experimental investigation on the thermal properties and electrical conductivity of the new microencapsulated phase change material by entrapping of stearic acid (SA) into PANI (polyaniline) shell through self-assembly method. Experimental results reveal that PANI nuclei grew on the surface of SA, and then copied its original morphological structure and finally exhibited peony flower-like morphology. The two components have good compatibility and have no chemical reaction both in the process of fabrication and subsequent use, while hydrogen bondings between the imino groups and carboxyl groups exist. The maximum mass fraction of stearic acid loaded in SA/PANI is determined as high as 62.1wt% without seepage of melted SA from capsules. Due to the secondary doping with carboxyl group, the composite phase change material embedded with SA exhibits improved electrical conductivity from 0.3968Scm−1 to 0.7042Scm−1 when compared to PANI. The phase change temperatures and latent heats of SA/PANI are measured to be 55.6°C and 113.02J/g for melting and, 50.8°C and 112.58J/g for freezing, respectively. TG analysis test revealed that the prepared SA/PANI composite PCM has high thermal durability in working temperature range. Moreover, the results of DSC, FT-IR, TG, conductivity investigation and thermal cycling test are all show that the thermal reliability and electrical conductivity of the SA/APNI have imperceptible changes. In total, the additional electrical conductivity, high heat storage potential and good thermal reliability and stability facilitated SA/PANI to be considered as a viable candidate for thermal energy storage, antistatic thermo-regulating textiles and other applications.

Polyaniline-coated chitosan-functionalized magnetic nanoparticles: Preparation for the extraction and analysis of endocrine-disrupting phenols in environmental water and juice samples

In the present study, chitosan (CHI) functionalized Fe3O4 magnetic microspheres coated with polyaniline (PANI) were synthesized for the first time. The chitosan-functionalized magnetic microspheres (Fe3O4@CHI) were synthesized by a co-precipitation method, and then aniline was polymerized on the magnetic core. The obtained Fe3O4@CHI@PANI microspheres were spherical core–shell structure with uniform size at about 100nm with 20–30nm diameter core. The microspheres had a high saturation magnetization of 32emug−1, which was sufficient for magnetic separation. The obtained Fe3O4@CHI@PANI magnetic microspheres were applied as magnetic adsorbents for the extraction of aromatic compounds via π–π interaction between polyaniline shell and aromatic compounds. Three endocrine-disrupting phenols, including bisphenol A (BPA), 2, 4-dichlorophenol (2, 4-DCP), and triclosan (TCS) were selected as the model analytes to verify the extraction ability of Fe3O4@CHI@PANI. The hydrophilic chitosan-functionalized Fe3O4 core (Fe3O4@CHI) improved the dispersibility of Fe3O4@CHI@PANI microspheres, and then improve its extraction efficiency. The dominant parameters affecting enrichment efficiency were investigated and optimized. Under optimal condition, the proposed method was evaluated, and applied to the analysis of phenols in real water and juice samples. The results demonstrated the method based on Fe3O4@CHI@PANI magnetic microspheres had good linearity (R2>0.996), and limits of detection (0.10–0.13ngmL−1), high repeatability (RSD<6.6%) and good recovery (85.0–106.7%).

Switching plasmon coupling through the formation of dimers from polyaniline-coated gold nanospheres.

Active modulation of the plasmon coupling in homodimers of polyaniline (PANI)-coated Au nanospheres is achieved by changing the proton-doping state of the PANI shell. Such a PANI-enabled modulation of the plasmon coupling in the dimers gives rise to remarkable spectral shifts, which show an exponential dependence on the interparticle gap distance. For the dimer with a 10 nm PANI shell thickness and a 0.5 nm gap distance, the shift of the stronger scattering peak in response to the active modulation reaches 231 nm. Electrodynamic simulations reveal that the shift of the dipolar bonding plasmon mode dominates the position variation of the stronger scattering peak for the dimers with different gap distances. Moreover, the quadrupolar bonding plasmon mode can be turned on and off by controlling the proton-doping state of the dimers with gap distances of less than ∼3 nm. These results are of high importance for fundamentally understanding the sensitivity of coupled plasmon resonance modes to the dielectric environment, as well as for designing active plasmonic devices with high modulation performances.

Tunable band gap and coercivity of bismuth ferrite–polyaniline core–shell nanoparticles: the role of shell thickness

We report a tunable band gap of bismuth ferrite–polyaniline core–shell nanoparticles from 2.24 to 1.98 eV and the variation of coercivity from 118 to 100 Oe, by varying the thickness of the polyaniline shell.