ELECTROSTATIC INTERACTION HYBRIDS FROM WATER-BORNE CONDUCTIVE POLYANILINE AND INORGANIC PRECURSOR CONTAINING CARBOXYL GROUP

Electrostatic interaction conductive hybrids were prepared in water/ethanol solution by the sol-gel process from inorganic sol containing carboxyl group and water-borne conductive polyaniline （cPANI）. The electrostatic interaction hybrids film displayed 1-2 orders of magnitude higher electrical conductivity in comparison with common hybrids film, showing remarkable conductivity stability against water soaking. Most strikingly, it displayed ideal electrochemical activity even in a solution with pH = 14, which enlarged the conducting polyaniline application window to strong alkaline media.

Conductive Polyaniline/Cellulose/Graphite Composite Films with High Thermal Stability and Antibacterial Activity

Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide monohydrate(NMMO) and regenerated in water to form the matrix. GP was dispersed in the NMMO solvent prior to the dissolution of the cellulose, and PANI was deposited on the surfaces of the cellulose/GP films by in situ chemical polymerization. The structures of the PANI/cellusose/GP composite films were investigated using X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy(SEM), and SEM/energy-dispersive X-ray spectroscopy. The mechanical strengths, thermal stabilities, conductivities, and antibacterial activities of the films were studied in detail. The results showed that GP formed a multilayered structure in the cellulose matrix and that the PANI nanoparticles were tightly wrapped on the film surface. The film thickness increased from 40 mm to 100 mm after the addition of GP and PANI. The tensile strength of the composite films was 80~107 MPa, with the elongation at break being 3%~10%. The final residual weight of the composite films was as high as 65%, and the conductivity of the composite films reached 14.36 S/m. The cellulose matrix ensured that the films were flexible and exhibited desirable mechanical properties, while the GP filler significantly improved the thermal stability of the films. The PANI coating acted as a protective layer during burning and provided good electrical conductivity and antibacterial activity against Escherichia coli; both of these characteristics were slightly enhanced by the incorporation of GP. These PANI/cellulose/GP composite films should be suitable for use in electronics, antistatic packing, and numerous other applications.

FERROFLUID CONTAINING SOLUBLE CONDUCTIVE POLYANILINE AND ITS FREESTANDING FILMS

Ferrofluid containing highly conductive polyaniline (PANI) was prepared, in which soluble PANI solutions dopedwith 10-camphorsulfonic acid (CSA) and dodecyl benzenesulfonic acid (DBSA) were used as the basic solution and Fe_3O_4nanoparticles (d = 10 nm) as the magnetic material. Moreover, the freestanding films of the resulting ferrofluid can beobtained by an evaporation method. The electrical and magnetic properties of the ferrofluid or its films can be adjustedthrough changing the content of PANI and Fe_3O_4. High saturated magnetization (≈ 30 emu/g) and high conductivity(≈ 250 S/cm) of the composite films can be achieved when the composite film contains 26.6 wt% of Fe_3O_4. In particular, itwas found that the composite films exhibit a super-paramagnetic behavior (Hc = 0) attributed to the size of Fe_3O_4 particles on the nanometer scale.

SYNTHESIS OF CONDUCTIVE POLYANILINE VIA OXIDATION BY MnO_2

A unique process of chemical oxidation polymerization of aniline using manganese dioxide (MnO2) as the oxidizing agent in an aqueous medium is described. The reaction between aniline and MnO2 follows a mechanism by which the organic monomer is oxidized while the metal oxide undergoes reductive dissolution. The effects of the amount of oxidizing agent and aniline, pH and temperature of the reactive system, type of acid on the yield and conductivity of polyaniline are discussed. The resulting polyaniline was characterized by IR and UV-Vis spectrometry. Polyaniline with a conductivity of 12.5 S/cm was obtained using 0.033 mol of aniline oxidized by 0.023 mol MnO2 in the presence of 100 mL of 2.7 mol/L HCl at 25degreesC for 4 h.

Electroanalytical studies on electrically conductive polyaniline： Nylon-6,6 composite film

Electrically conductive composite films ofpolyaniline and nylon-6.6 are prepared by diffusing aniline followed by oxidative polymerization of aniline into nylon-6.6 matrix. In order to determine the diffusion coefficient for the chloride ion diffusion into the composite matrix electrochemically, galvanostatic pulse method is used and the diffusion coefficient is estimated to be -6.48× 10^-17 cm^2s^-1. The results are discussed in view of them being potential replacement materials for battery. electrodes and sensors devices.

PREPARATION OF POLYANILINE/ACETYLENE BLACK COMPOSITE AS HOLE CONDUCTOR IN SOLID-STATE DYE-SENSITIZED SOLAR CELL

A clay-like conductive material comprising polyaniline（PANI）-acetylene black particles is fabricated as a hole conductor for dye sensitized solar cell（DSSC）.The results show that the introduction of acetylene black into the polymer electrolyte improves the photovoltaic behavior of solid-state DSSC,owing to the increase of the hole mobility of PANI electrolyte,the improvement of the wetting quality of the composite electrolyte,and the reinforcement of interface contact between electrode and the electrolyte.Finally,the overall energy conversion efficiency of DSSC with PANI-50%（in weight）acetylene black electrolyte is 48% of that of liquid DSSC.Therefore,the PANI-acetylene black composition is a credible alternative to hole conductor in application of solid DSSC.

Antibacterial Effect of the Conducting Polyaniline

Excellent antibacterial performance of polyaniline （PAni） against Escherichia coli and Gram-positive Staphylococcus aureus microorganisms has been demonstrated under both dark and visible light conditions. The electrostatic adherence between the PAni molecules and the bacteria may play a very important role for the antibacterial reaction of the PAni. As a result of our investigation, conducting PAni and its composites/blends are believed to be useful as a new type of antibacterial agent, self-clean as well as multifunctional material for improving the human health and living environment.

Hemoglobin-biocatalyzed Synthesis of Conducting Molecular Complex of Polyaniline and Lignosulfonate

A new biocatalyst route for the synthesis of a conducting polyaniline （PANI）/ lignosulfonate （LGS） complex was presented.Four different catalysts such as hemoglobin （Hb）,5,10,15,20-tetrakis （meso-hydroxyphenyl） porphyrin,iron （II） tetrasulfophthalocyanine and ferric chloride were used to polymerize aniline in the presence of a natural polyelectrolytes template LGS.The experimental results show that Hb is an effective catalyst in this case and the synthesis is simple,and the conditions are mild in that the polymerization may be carried out in lower pH （1.0-4.0） buffered solution and optimal pH of 2.0.Varying concentrations of aniline,LGS and H2O2 in feed the favorable conditions for the production of PANI were determined.UV-vis absorption,FTIR,elemental analysis,conductivity,cyclic voltammetry and thermogravimetric analyses confirm the formation of thermally stable and electroactive PANI.

Iron(Ⅱ) tetrasulfophthalocyanine mimetic enzymatic synthesis of conducting polyaniline in micellar system

Iron(Ⅱ) tetrasulfophthalocyanine(FeTSPc) ,as a novel mimetic enzyme of peroxidase,was used in the synthesis of a conducting polyaniline(PANI) /sodium dodecylsulfate(SDS) complex in SDS aqueous micellar solutions. The effects of pH,concentrations of aniline,SDS and H2O2,and reaction time on polymerization of aniline were studied in this case as shown by UV-Vis absorption spectroscopy. The results show that a wide range of pH(0.5-4.0) is required to produce the conducting PANI,and the optimal pH is 1.0 in SDS micelle. The optimal concentrations of aniline,SDS and H2O2 in feed,and reaction time in this case for the production of conducting PANI are respectively 10 mmol/L,10 mmol/L,25 mmol/L,and 15 h. FT-IR spectrum,elemental analysis,conductivity,cyclic voltammetry and thermogravimetric analysis confirm the thermal stability and electroactive form of PANI.

Preparation and Properties of Water-based Conducting Polyaniline

A convenient way to prepare water soluble or water dispersible conducting polyaniline was developed by employing protonic acid dopants containing hydrophilic ethyleneoxide oligomer as counter-ion. The conducting polyaniline possesses electrical conductivity in the range of 10^(-3) to 10^(-2)S/cm depending on the chosen dopant, and it displays an excellent electrochemical redox reversibility in non aqueous systems.

POSITRON ANNIHILATION AND CONDUCTIVITY MEASUREMENTS ON POLYANILINE

The positron lifetime spectra and electrical conductivities have been measured for polyaniline as a function of protonation level ([H+] from 10-7-1000.8 mol/L). Weobserved that (1) the short lifetime τ1, which was related to electron density in bulk,decreased with the protonation level; (2) the intermediate lifetime τ2≈360ps, almost remaining constant, whereas its intensity I2 increased with increasing protonation level which was related to the conductivity of material. These results are discussed in terms of conducting island model.

Synthesis of Polyaniline-Fe_3O_4 Nanocomposites and Their Conductivity and Magnetic Properties

By using inorganic Fe3O4 nanoparticles of different content as nucleation sites, PAn-Fe3O4 nanorods were successfully synthesized through a simple, conventional, and inexpensive one-step in-situ polymerization method. The TEM images revealed the size and morphology of the resultant nanocomposite. The EDS pattern confirmed the existence of Fe3O4 in the composite. The FT-IR spectral analysis confirmed the formation of PAn encapsulated Fe3O4 nanocomposite. With the content of Fe3O4 increasing, the conductivity of the nanocomposites gradually decreases, meanwhile, the saturation magnetization increases and reveals a super paramagnetic behavior. With controllable electrical, magnetic, and electromagnetic properties, the well-prepared nanocomposites may have the potential applications in chemical sensors, catalysis, microwave absorbing, and electro-magneto-rheological fluids, etc.

Wet Chemical Synthesis of Entangled Nano-fibrous Conducting Polyaniline(PANI) Mesh: Effect of Heating and Stirring

An effect of heating and stirring in a facile wet chemical route to synthesize entangled nanofibrous mesh of doped polyaniline(PANI) was reported. The structural, morphological, and optical properties of PANI nano-fibers were found to be dependent on synthesis temperature and stirring. The XRD analysis confirms nano PANI formation with 2θ peaks around 15°, 21°, and 25° for(011),(020), and(200) crystal planes, respectively. The average crystallite size varies between 25 nm to 60 nm due to change in synthesis conditions. The SEM analysis reveals the clustered granule formation for PANI sample synthesized at 28 and 60 ℃ under continuous stirring, whereas, unstirred synthesis at 60 ℃ shows entangled nano-fibrous mesh morphology. The TGA study shows better thermal stability for PANI mesh over granular PANI. The FTIR spectra validates the emeraldine salt PANI formation with peaks corresponding to C-H, C-N, N=Q=N, N=B=N, and N-H vibration bands. The UV-Vis analysis shows the major absorbance peaks around λ: 340 nm(π-π* transition of benzenoid ring), and λ: 800 nm(π-π*, polaron-π*, π-polaron transitions). The dense entangled nano-fibrous coating of PANI synthesized at 60 ℃ without stirring shows highest electrical conductivity of 3.79 S·cm^-1.

CONFINING CONDUCTING POLYANILINE IN A STABLE INORGANIC NETWORK

Water soluble conducting polyaniline with electrical conductivity of 10^(-1)-10^(-2) S/cm was prepared employingdopant induced water solubility technology. The water resistance of the conducting film was significantly improvedemploying sol-gel hybrids method, especially when the conductive polyaniline loading was below 30 wt%. The reason forthe improvement is that the conducting polyaniline chains are confined in a stable inorganic network.

Radiation Induced Variations of Electrical Conductivity in Polyaniline

Induced variations of electrical conductivityσdc of polyaniline byγ-radiation have been studied,σdcdc increases from 2.2 to 2.7S/cm due to radiation with a dose of 30-40Mrad.EPR results show that spin concentration increases at the same rate asσdc.The characteristics ofσdc versus temperature fit to Inσdc∝T^(-1) before irradiation,before irradiation,but to Inσdc∝T^(-1/4) after irradiation.

Charge transport in conducting polyaniline co-doped with sulfosalicylic acid and dodecylbenzoyl sulfonic acid

We prepared conducting polyaniline （PAn） co-doped with sulfosalicylic acid （SSA） and dodecylbenzoyl sultonic acid （DBSA） in micro-emulsive polymerization, and studied its charge transport behaviors based on the measurement of its electrical conductivity in the temperature range between 203 K and 298 K. The conductivity was found to increase with temperature, similar to the case in semiconductors. Analyzing the experimental data with three models, namely the charge-energy-limitedtunneling model, Kivelson model and the three-dimensional variable range hopping （3D-VRH） model demonstrated that these models all describe well the charge transport behaviors of PAn co-doped with SSA and DBSA within the mentioned temperature range. From calculation with the 3D-VRH model, the hopping distance of the conducting PAn is obviously larger than its localization length. The PAn doped with SSA and DBSA enjoys desirable crystallinity due to the co-doping of two functional sulfonic acids. The macroscopic conductivity may correspond to three-dimensional transport in the network of the bundles, and the metallic islands may be attributed to quasi-one-dimensional bundles.

Highly Fluorescent Conducting Polymer Hybrid Materials Based on Polyaniline-Polyethylene Glycol-Arsenic Sulphide

Highly fluorescent binary and ternary hybrid materials based on polyaniline, polyethylene glycol (PEG) and arsenic sulphide have been prepared via oxidative chemical polymerization and characterized by FT-IR and powder X-ray diffraction techniques. Thermogravimetric analysis showed that all the materials are thermally stable up to 250℃. The optical behaviour was investigated using UV-Vis. and fluorescence spectroscopy. Fluorescence spectra of polyaniline and its hybrids were found to be concentration dependent, and concentrations were optimized to achieve maximum intensity of emission. Aggregation caused quenching (ACQ) may be the possible reason for concentration dependent emission. Hybrids showed significantly enhanced fluorescence than polyaniline. The AC electrical conductivity was also measured and found to be better for hybrids than the polyaniline. In the PAni-PEG-As2S3 hybrid, the conductivity was found to be 9.57 × 10-1 S/cm at 100 KHz. This valuable improvement in luminescent property and conducting behaviour may be useful in various optoelectronic and electronic applications.

STUDIES ON THE ELECTRICAL CONDUCTIVITY OF FREE-STANDING FILMS OF POLYANILINE

An insulate to metal transition was investigated based on the measurements of the dependence of the conductivity, activation energy on the protonation state of polyaniline (PANI). An isotropy in conductivity for stretched salt form of PANI was observed.For salt film of PANI, the Ⅰ-Ⅴ curve obeys Ohm's law, which shows a typical metal behavior, however, for base film or film with low protonation state, it can be explained by Space Charge Limited Current (SCLC). It is also found that the Ⅰ-Ⅴ curve of base film of PANI is independent of the work function of electrodes and the polymerization temperature.