Fabrication of polyaniline-silver nanocomposites by chronopotentiometry in different ionic liquid microemulsion systems

Chronopotentiometry is employed to prepare polyaniline-silver (PANI-Ag) nanocomposite films in water-in-ionic liquid (W/IL) microemulsion and ionic liquid-in-water (IL/W) microemulsion. The resulted nanocomposites are characterized by scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction. It is demonstrated that the PANI-Ag nanocomposite prepared in W/IL microemulsion is nanofibrous and the Ag nanocrystals with 5 nm diameter are dispersed homogeneously, whereas the morphology of the PANI-Ag nanocomposite prepared in IL/W microemulsion exhibits dendritic structure and the diameter of Ag nanocrystals is 50-100 nm. Further, the effects of different microemulsion systems and electrochemical synthesis conditions on the electrochemical properties of the nanocomposite films are studied by cyclic voltammetry and electrochemical impedance spectroscopy. The pure PANI films are also made for comparative purpose. It is found that the special structures of the PANI-Ag nanocomposite result in more excellent electrochemical activity than that of the pure PANI.     

Fabrication and characterization of polyaniline-znO hybrid nanocomposite thin films

Polyaniline (PANI)-ZnO nanocomposite thin film has been successfully fabricated on glass substrates by using vacuum deposition technique. The as-grown PANI-ZnO nanocomposite thin films have been characterized using X-ray diffraction, Scanning Electron Microscopy, Atomic Force Microscopy, UV-visible spectrophotometer and Fourier Transform Infrared (FTIR) spectroscopy, respectively. X-ray diffraction of as-grown film shows the reflection of ZnO nanoparticles along with a broad peak of PANI. The surface morphology of nanocomposite films has been investigated using scanning electron microscopy and atomic force microscopy. The hypsochromic shift of the UV absorption band corresponding to pi-pi* transition in polymeric chain of PANI and a band at 504 cm(-1) due to ZnO nanoparticles has been observed in the FTIR spectra. The hydrogen bonding between the imine group of PANI and ZnO nanoparticle has been confirmed from the presence of the absorbance band at 1151 cm(-1) in the FTIR spectra of the nanocomposite thin films.     

Fe(3)O(4)@Au/polyaniline multifunctional nanocomposites: their preparation and optical, electrical and magnetic properties

Fe(3)O(4)@Au/polyaniline (PANI) nanocomposites were fabricated by in situ polymerization in the presence of mercaptocarboxylic acid. The mercaptocarboxylic acid was used to introduce hydrogen bonding and/or electrostatic interaction; it acts as a template in the formation of Fe(3)O(4)@Au/PANI nanorods. The morphology and structure of the resulting nanocomposites were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, x-ray diffraction and x-ray energy dispersion spectroscopy (EDS). It was found that the nanocomposites were rod-like with an average diameter of 153?nm, and they exhibited a core-shell structure. A UV-visible spectrometer, semiconductor parameter analyzer and vibrating sample magnetometer (VSM) were used to characterize the optical, electrical and magnetic properties of the Fe(3)O(4)@Au/PANI nanocomposites. It was interesting to find that these properties are dependent on the molar ratio of Au to Fe(3)O(4) when the molar ratio of Fe(3)O(4)@Au to PANI is fixed. The magnetic property of the Fe(3)O(4)@Au/PANI nanocomposite is very close to superparamagnetic behavior.     

Preparation and Antibacterial Activity of Three-component NiFe_2O_4@PANI@Ag Nanocomposite

A new three-component and magnetically responsive NiFe_2O_4@PANI@Ag nanocomposite has been fabricated by coating of nickel ferrite,NiFe_2O_4,nanoparticles with polyaniline(PANI) and subsequent immobilization of silver nanoparticles onto the surface of polyaniline shell.The as-prepared nanocomposite has been characterized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),and vibrating sample magnetometer(VSM).The saturation magnetization of the NiFe_2O_4core decreases dramatically after coating with polyaniline and silver nanoparticles,however,the nanocomposite NiFe_2O_4@PANI@Ag can be still separated from solution media through magnetic decantation.The antibacterial activity of the synthesized nanocomposite was studied and compared with those of naked NiFe_2O_4,NiFe_2O_4@PANI and some standard antibacterial drugs.     

Preparation and microwave absorption properties of polyaniline/Mn0.8Zn0.2Fe2O4 nanocomposite in 2–18 GHz

The polyaniline/Mn_0.8Zn_0.2Fe₂O₄(PANI/MZF) nanocomposite was prepared by an in situ polymerization method. The samples were characterized by Fourier transform infrared spectrometer, X-ray diffraction, scanning electron microscope and vibrating sample magnetometer. The complex permittivity and complex permeability for the nanocomposites were measured by wave-guide method with vector network analyzer in 2.0–18.0 GHz. The reflection losses (R _L ) of the nanocomposites were investigated according to the wave transmission theory. The results showed the maximum reflection loss of the PANI/MZF nanocomposite was about ?20.6 dB at 14.4 GHz with a bandwidth of 5.6 GHz. In conclusion, a wider absorption frequency range could be obtained by adding polyaniline contain in the MZF ferrite. The PANI/MZF nanocomposite is a good microwave shielding and absorbing materials at higher frequency.     

Synthesis of a soluble polyaniline–ferrite composite: magnetic and electric properties

We report the preparation of a processible magnetite/polyaniline (Fe₃O₄/PANI) nanocomposite, containing dodecylbencensulfonic acid (DBSA) as a surfactant and dopant, with both magnetic and conducting properties. Different amounts of Fe₃O₄ nanoparticles were successfully disposed with FeCl₃ solution to prevent their aggregation in the solution by the application of common ion effect. The magnetic properties of the resulting composites were investigated by a quantum design magnetometer (PMPS). The (Fe₃O₄/PANI) nanocomposite showed at 300 K no loop of hysteresis indicating the superparamagnetic nature. The saturation magnetization varies from 0.167 to 28.45 emu/g with increasing Fe₃O₄ content. Zero field cooling (ZFC) and Field cooling (FC) profiles showed that the polyaniline matrix allows each ferrite nanoparticles to behave independently and interparticle interactions are not important for iron oxide content lower than 36 wt.%. The electrical conductivity of composites was found to be higher than that of the pure PANI in spite of the insertion of the insulating material Fe₃O₄ particles. It is noticeable that conductivity increases with low Fe₃O₄ particles content and then decreases. Structural characterization by X-ray diffraction (XRD), UV spectroscopy and thermogravimetric analysis (TGA) have been performed.     

Microstructure,electrical and humidity sensing properties of TiO<Subscript>2</Subscript>/polyaniline nanocomposite films prepared by sol–gel spin coating technique

High sensitive resistive type humidity sensor based titanium oxide/polyaniline (TiO₂/PANI) nanocomposite thin films prepared by a sol–gel spin coating technique on an alumina substrate. The resultant nanocomposites were characterized by using X-ray diffraction (XRD), Field emission electron microscopy, Fourier transform infrared spectroscopy (FTIR), UV–Vis absorbance and energy dispersive spectra analysis. In the XRD patterns of both pure and TiO₂/PANI composite confirms the deposition of PANI on TiO₂ and the average size of the composite particle was found to be 32 nm. Large number of nano grain surface being covered by PANI, which agrees very well with the results obtained by XRD studies. FTIR and UV–Vis spectra reveal that the PANI component undergoes an electronic structure modification as a result of the TiO₂ and PANI interaction. The room temperature resistivity was found to be for TiO₂ and TiO₂/PANI nanocomposite films 1.42?×?10⁶ and 2.56?×?10³ Ω cm respectively. The obtained TiO₂/PANI nanocomposites sensor exhibited higher humidity sensing performance such as high sensitivity, fast response (20 s) and recovery time (15 s) and high stability.     

Structural,dielectric, ac conductivity and electromagnetic shielding properties of polyaniline/Ni<Subscript>0.5</Subscript>Zn<Subscript>0.5</Subscript>Fe<Subscript>2</Subscript>O<Subscript>4</Subscript> composites

A conducting polymer, polyaniline (PANI)/Ni_0.5Zn_0.5Fe₂O₄ composites with high dielectric absorbing properties and electromagnetic shielding effectiveness at low frequencies were successfully synthesized through a simple in situ emulsion polymerization. PANI was doped with hydrochloric acid to improve its electrical properties and interactions with ferrite particles. PANI/Ni_0.5Zn_0.5Fe₂O₄ composites were characterized by X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and thermal gravimetric analysis. Frequency dependence of dielectric and ac conductivity (σ_ac) studies have been undertaken on the PANI/Ni_0.5Zn_0.5Fe₂O₄ composites in the frequency range 50 Hz–5 MHz. The electrical conduction mechanism in the PANI/Ni_0.5Zn_0.5Fe₂O₄ is found to be in accordance with the electron hopping model. Further, frequency dependence of electromagnetic interference (EMI) shielding effectiveness (SE) is studied. The EMI shielding effectiveness is found to decrease with an increase in the frequency. The maximum value 55.14 dB of SE at 50 Hz was obtained at room temperature for PANI/Ni_0.5Zn_0.5Fe₂O₄ composites in the 50 Hz–5 MHz frequency range. PANI/Ni_0.5Zn_0.5Fe₂O₄ composites were demonstrated as a promising functional material for the absorbing of electromagnetic waves at low frequencies because of a large amount of dipole polarizations in the polymer backbone and at the interfaces of the Ni–Zn ferrite particles and PANI matrix.     

Synthesis of ultra-fine conducting polyaniline micro/nanotubes using fiber template and their NH3 gas sensitivity

We have recently fabricated ultra-fine conducting polyaniline (PANI) tubes with high gas sensitivity. This route includes two steps. Firstly, aniline polymerizes on the surface of a suitable fiber template prepared by electrospun nitrocellulose (NC). Then, the NC fiber template is dissolved and the ultra-fine PANI tubes are obtained. The structure of the conducting PANI tubes is characterized by IR spectrum and wide-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicate that the PANI shows the shape of ultra-fine tubes with average inner diameter of 250-350 nm. The wall thickness of the ultra-fine PANI tubes increases with increasing the content of oxidant. The conductivity of the doped PANI tubes is about 6.9 x 10(-2) S. The results of gas sensitivity of the ultra-fine PANI tubes indicate that the PANI tubes can act as "electronic nose" to detect toxic NH3 gas below 20 ppm.     

Enhancement of electroconductivity of polyaniline/graphene oxide nanocomposites through in situ emulsion polymerization

The present study introduces a systematic approach to disperse graphene oxide (GO) during emulsion polymerization (EP) of Polyaniline (PANI) to form nanocomposites with improved electrical conductivities. PANI/GO samples were fabricated by loading different weight percents (wt%) of GO through modified in situ EP of the aniline monomer. The polymerization process was carried out in the presence of a functionalized protonic acid such as dodecyl benzene sulfonic acid, which acts both as an emulsifier and protonating agent. The microstructure of the PANI/GO nanocomposites was studied by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–Vis spectrometry, Fourier transform infrared, differential thermal, and thermogravimetric analyses. The formed nanocomposites exhibited superior morphology and thermal stability. Meanwhile, the electrical conductivities of the nanocomposite pellets pressed at different applied pressures were determined using the four-probe analyzer. It was observed that the addition of GO was an essential component to improving the thermal stability and electrical conductivities of the PANI/GO nanocomposites. The electrical conductivities of the nanocomposites were considerably enhanced as compared to those of the individual PANI samples pressed at the same pressures. An enhanced conductivity of 474 S/m was observed at 5 wt% GO loading and an applied pressure of 6 t. Therefore, PANI/GO composites with desirable properties for various semiconductor applications can be obtained by in situ addition of GO during the polymerization process.     

Synthesis and ferrimagnetic properties of novel Sm-substituted LiNi ferrite–polyaniline nanocomposite

Polyaniline (PANI)–LiNi_0.5Sm_0.08Fe_1.92O₄ nanocomposite was synthesized by an in situ polymerization of aniline in the presence of LiNi_0.5Sm_0.08Fe_1.92O₄ ferrite. The products were characterized by powder X-ray diffractometer (XRD), Fourier transform infrared (FTIR) and UV–visible absorption spectrometer, thermogravimetric analyser (TGA), atomic force microscope (AFM) and vibrating sample magnetometer (VSM). The results of XRD, FTIR and UV–visible spectra confirmed the formation of PANI–LiNi_0.5Sm_0.08Fe_1.92O₄ composite. AFM study showed that ferrite particles had an effect on the morphology of the composite. TGA revealed that the incorporation of ferrite improved the thermal stability of PANI. The nanocomposite under applied magnetic field exhibited the hysteresis loops of ferrimagnetic nature at room temperature. The bonding interaction between ferrite and PANI in the nanocomposite had been studied.     

Preparation of new antimony(0)/polyaniline nanocomposites by a one-pot solution phase method

The new Sb(0)/PANI nanocomposite was successfully synthesized by a one-pot solution phase method. Sb(0) particles were first prepared by the reduction of SbCl₅ or SbCl₃ using t-BuONa-activated NaH in THF. A ligand exchange with aniline on t-BuONa-stabilized Sb(0) particles yielded aniline-stabilized particles. The Sb(0)/PANI nanocomposite was finally obtained by polymerizing aniline-stabilized Sb(0) particles by using ammonium persulfate. The morphology and the structure of the nanocomposite was examined by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Results obtained show that the Sb(0) precursor has a great influence on the size and the crystallinity of Sb(0) nanoparticles dispersed in PANI.     

Interfacial synthesis of platinum loaded polyaniline nanowires in poly(styrene sulfonic acid)

Polyaniline-poly(styrene sulfonic acid)-platinum (PANI-PSS-Pt) composite is prepared through an interfacial polymerization route. The composite is obtained by incorporating Pt nanoparticles into conductive PANI matrix by the reduction of Pt⁴⁺ ions to Pt nanoparticles during the oxidative polymerization of aniline in PSS as medium. The interfacial synthesis offers the microenvironment for the growth of PANI nanostructures with simultaneous incorporation of Pt nanoparticles to result PANI-PSS-Pt nanocomposite. PANI-PSS-Pt nanocomposite is characterized by UV-Vis absorption spectroscopy, FTIR spectroscopy, scanning microelectronic microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS).     

Growth of hydroxyapatite on physiologically clotted fibrin capped gold nanoparticles

The growth of hydroxyapatite (HAp) on physiologically clotted fibrin (PCF)-gold nanoparticles is presented for the first time by employing a wet precipitation method. Fourier transform infrared (FTIR) spectroscopy confirmed the characteristic functionalities of PCF and HAp in the PCF-Au-HAp nanocomposite. Scanning electron microscopy (SEM) images have shown cuboidal nanostructures having a size in the range of 70-300?nm of HAp, whereas 2-50?nm sized particles were visualized in high-resolution transmission electron microscopy (TEM). Energy-dispersive x-ray (EDX) and x-ray diffraction (XRD) studies have confirmed the presence of HAp. These results show that gold nanoparticles with PCF acted as a matrix for the growth of HAp, and that PCF-Au-HAp nanocomposite is expected to have better osteoinductive properties.     

Synthesis of multi-walled carbon nanotube/silica nanoparticle/polystyrene microsphere/polyaniline based hybrids for EMI shielding application

Novel polystyrene microsphere (PSMS)-based PSMS/Si and polystyrene/silica nanoparticle/multi-walled carbon nanotube (PS/Si/MWCNT) nanocomposite has been prepared using in situ sol-gel and chemical amalgamation methods. Aniline monomer was introduced by in situ route to form PSMS/PANI, PSMS/PANI/Si and PSMS/PANI/Si/MWCNT nanocomposite. FESEM of nanocomposite indicated core-shell spherical and tubular morphology. Glass transition temperature (T_g) and maximum decomposition temperature (T_max) of PSMS/PANI/Si/MWCNT nanocomposite were found as 295°C and 524°C, respectively, which were higher than the PSMS/PANI (T_g = 245°C; T_max = 387°C) and PSMS/PANI/Si (T_g = 257°C; T_max = 388°C) nanocomposite. For nanocomposite dispersion, tetrahydrofuran was studied as fine solvent. XRD depicted amorphous nature of PSMS/Si and PSMS/PANI/Si; however MWCNT reduced amorphous character of PSMS/PANI/Si/MWCNT. Electromagnetic interference (EMI) shielding effectiveness improved from 0.1 dB (PSMS) to 12.3 dB (PSMS/PANI/Si) to 24.5 dB (PSMS/PANI/Si/MWCNT). The increase in EMI shielding effectiveness was also observed with variation in log of conductivity from ?14 mho m^?1 (PSMA) to 1.17 mho m^?1 (PSMS/PANI/Si/MWCNT).     

Highly ordered mesostructured silica spheres as template for polyaniline nanofibres: synthesis,characterisation and their electrochemical properties

Ordered micrometre-sized silica spheres with uniform morphology and mesoporous structures were prepared by a temperature-induced and polyethylene glycol-assisted assembly method. The porous surface of the silica spheres was used for the chemical polymerisation of aniline, as well as a sacrificial template for synthesis of polyaniline (PANI) nanofibres. The morphologies of PANI nanostructures were characterised by scanning electron microscopy and transmission electron microscopy. Microstructural analysis and properties evaluation of the as-prepared products were characterised by X-ray diffraction, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy and N₂ adsorption–desorption analysis. TGA results demonstrated that about 95% of the mesoporous material has been utilised for the synthesis of PANI nanofibres. Their electron transfer properties were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy. CV experiment shows that the obtained PANI nanofibres have good electrochemical activity, which can be attributed to a higher number of accessible redox sites available during the synthesis process. The value of time constant (Γ) of PANI nanofibres based electrode was 0.0217?ms. The lower Γ-value is usually preferred for electrochemical capacitor for fast charge–discharge processes; hence, these PANI nanofibres based materials and their composites have the potential to be used as supercapacitor electrodes for supercapacitor applications.     

One-step synthesis of conductive graphene/polyaniline nanocomposites using sodium dodecylbenzenesulfonate: preparation and properties

The preparation of conducting graphene/polyaniline–sodium dodecylbenzenesulfonate (PANI–SDBS) nanocomposites using synthesised graphene as the starting material is successfully conducted in the present study. The effect of the anionic surfactant SDBS on the properties of the graphene/PANI–SDBS nanocomposites is studied. The structure and morphology of the synthesised nanocomposites are characterised by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–vis) spectrophotometry, X-ray diffraction and atomic force microscopy (AFM). The electrical conductivity properties of the resulting nanocomposites are determined using a resistance meter measurement system. The FESEM and TEM images reveal that the addition of SDBS surfactant to the PANI transforms the nanofibers of the PANI to a nanosphere morphology of PANI–SDBS. FTIR and UV–vis studies reveal that the conductive graphene/PANI–SDBS nanocomposites are successfully synthesised. AFM characterisation shows that the addition of graphene reduces the root mean square roughness of the surface of the PANI. The electrical conductivity and thermal stability of the PANI are improved after the introduction of SDBS. The nanocomposites containing a 5 wt% graphene loading exhibit the highest electrical conductivity of 2.94?×?10^?2 S/cm, which is much higher than that of PANI (9.09?×?10^?6 S/cm).     

Nanocomposites of CoO and a mesoporous carbon (CMK-3) as a high performance cathode catalyst for lithium-oxygen batteries

A nanocomposite of CoO and a mesoporous carbon (CMK-3) has been studied as a cathode catalyst for lithium-oxygen batteries in alkyl carbonate electrolytes. The morphology and structure of the as-prepared nanocomposite were characterized by field emission scanning electron microscopy, transmission electron microscopy and high resolution transmission electron microscopy. The electrochemical properties of the mesoporous CoO/CMK-3 nanocomposite as a cathode catalyst in lithium-oxygen batteries were studied using galvanostatic charge-discharge methods. The reaction products on the cathode were analyzed by Fourier transform infrared spectroscopy. The CoO/CMK-3 nanocomposite exhibited better capacity retention than bare mesoporous CMK-3 carbon, Super-P carbon or CoO/Super-P nanocomposite. The synergistic effects arising from the combination of CoO nanoparticles and the mesoporous carbon nanoarchitecture may be responsible for the optimum catalytic performance in lithium-oxygen batteries.      

Structural characteristics and biocompatibility of a casein-based nanocomposite for potential biomedical applications

Natural polymers have attracted increasing attention for biomedical applications owing to their biocompatibility. Casein possesses several interesting properties that make it a good candidate for biomedical materials. In this context, a novel casein-based nanocomposite was created by adding organized montmorillonite (OMMT) as a reinforcing material and ethylene glycol diglycidyl ether (EGDE) as a cross-linking agent. Fourier transform infrared spectroscopy indicated that EGDE had reacted with casein to form a network structure. X-ray diffraction and transmission electron microscopy showed a transformation of the OMMT structure from exfoliated to intercalated with an increase in the amount of OMMT. Scanning electron microscopy revealed that the nanocomposite with low OMMT content was characterized as high porosity. The addition of OMMT and EGDE improved the physical properties of the casein composites, resulting in a lower swelling ratio, higher thermal stability, lower biodegradation rate, and stronger mechanical properties compared with neat casein. A cell counting kit-8 assay demonstrated that the prepared nanocomposite films are biocompatible. These observations suggest that the casein nanocomposite is a promising material for biomedical applications.