Yield Of Polyaniline Research Articles

The ways of connecting crystalline phases having tubular cavities like stringing beads: New conductive polymer composites prepared by the polymerization of aniline in highly oriented ε crystalline phase of syndiotactic polystyrene

We prepared the syndiotactic polystyrene (SPS) films such that its ε crystalline phase and its channeling cavity were oriented to be parallel to the direction of the film thickness with a high regularity. Moreover, we introduced aniline molecules to these oriented cavities and successfully polymerized them to polyaniline (PANI). This is the mild and intelligent way of preparing polymer composites where the orientation and arrangements of the polymers are highly controlled. These SPS/PANI films showed the electrical conductivity to be ~0.05 S/cm and the maximum molecular weight of PANI to be 30 units of aniline. Interestingly, the film thickness was found to increase by 110–200%. This is because some ε crystalline phase is connected by the polymerization of aniline in the cavity, like sewing beads (some SPS ε crystalline phase) with a thread (polymerizing PANI). The paper examined the reaction temperature of aniline in SPS films, and other properties such as conductivity, molecular weight, and yield of PANI.

Cost Effective Chemical Oxidative Synthesis of Soluble and Electroactive Polyaniline Salt and Its Application as Anticorrosive Agent for Steel.

The cost effective synthesis of electroactive polyaniline (PANI) while retaining its desirable properties is one of the most debatable and challenging tasks for researchers in the field. Herein, we report a cost effective inverse emulsion polymerization pathway for the synthesis of soluble and processable PANI salt by using diesel as a novel dispersion medium. Different reaction parameters and their effects on the properties and yield of polyaniline were optimized. The polymer exhibited a highly porous morphology and was found to be stable up to 417 °C. The PANI salt showed good solubility in common solvents, such as chloroform, N-Methyl-2-pyrrolidone (NMP), dimethyl sulphoxide (DMSO) and in a 1:3 mixtures by volume of 2-propanol and toluene. The coating of the synthesized PANI salt on stainless steel has shown good corrosion resistant behavior in marine water by reducing the corrosion rate to 67.9% as compared to uncoated stainless steel.

Study on a Microreaction Process for Synthesis of Polyaniline

ABSTRACTA catalytic continuous microreaction process for synthesis of polyaniline (PANI) under solar light was investigated. The polymerization of aniline was conducted via a photochemical method. The photopolymerization method yields a polymeric material that has been characterized by Fourier-transform infrared spectroscopy analysis and by scanning electron microscopy. It is shown that the functional groups and surface morphology are affected by solar incident energy where the PANI main vibrational bands become wider, resulting in higher concentration of rings. Results showed that solar intensity enhanced the average yield by 5% over that of indirect solar, while the average time of polymerization is reduced by 17%. The polymerization time was reduced by 20–​27% while the temperature was increased from 5°C​ to 25°C under indirect solar and direct solar, respectively. The yield of PANI is reduced from 94.0% to 84.2% as liquid hour space velocity (LHSV) is increased from 0.145 to 0.385 min−1. An optimum molar ratio of about 1.25 is found to give the maximum yield of PANI. Kinetic analysis revealed that a pseudo-first-order Langmuir–​Hinshelwood model is well expressing the oxidation rate of aniline over TiO2. The values of the adsorption equilibrium constant, , and the kinetic rate constant of surface reaction, , are 0.0209 and 0.791 (L−1g min−1), respectively. Comparison between microreactor's performance and performance of batch reactors from published literature was presented. The comparison confirmed the unique characteristics of the microreactor.

Advanced Synthesis of Conductive Polyaniline Using Laccase as Biocatalyst.

Polyaniline is a conductive polymer with distinctive optical and electrical properties. Its enzymatic synthesis is an environmentally friendly alternative to the use of harsh oxidants and extremely acidic conditions. 7D5L, a high-redox potential laccase developed in our lab, is the biocatalyst of choice for the synthesis of green polyaniline (emeraldine salt) due to its superior ability to oxidize aniline and kinetic stability at the required polymerization conditions (pH 3 and presence of anionic surfactants) as compared with other fungal laccases. Doses as low as 7.6 nM of 7D5L catalyze the polymerization of 15 mM aniline (in 24 h, room temperature, 7% yield) in the presence of different anionic surfactants used as doping templates to provide linear and water-soluble polymers. Aniline polymerization was monitored by the increase of the polaron absorption band at 800 nm (typical for emeraldine salt). Best polymerization results were obtained with 5 mM sodium dodecylbenzenesulfonate (SDBS) as template. At fixed conditions (15 mM aniline and 5mM SDBS), polymerization rates obtained with 7D5L were 2.5-fold the rates obtained with commercial Trametes villosa laccase. Moreover, polyaniline yield was notably boosted to 75% by rising 7D5L amount to 0.15 μM, obtaining 1g of green polyaniline in 1L-reaction volume. The green polymer obtained with the selected system (7D5L/SDBS) holds excellent electrochemical and electro-conductive properties displayed in water-dispersible nanofibers, which is advantageous for the nanomaterial to be readily cast into uniform films for different applications.

Optimization of the conductivity and yield of chemically synthesized polyaniline using a design of experiments

ABSTRACTThe electrical conductivity and yield of polyaniline (PANi) were optimized using a design of experiments (DOE). PANi samples were synthesized by the chemical oxidative polymerization of aniline using methane sulfonic acid as the dopant acid and ammonium persulfate as the oxidant. The main factors in the synthesis of PANi that can affect the conductivity were identified as (i) the concentration of dopant acid, (ii) oxidant‐to‐monomer ratio, and (iii) the addition rate of oxidant to monomer. Using a Box‐Behnken DOE method the regression equation, main effects plots, contour plots, and optimization plots for conductivity and yield were generated and analyzed. Under the optimized conditions of dopant acid concentration of 0.9M, an oxidant addition rate of 30 mL/h and an OM ratio of 0.9, PANi with a conductivity of 1.95 S/cm and yield of 95% was obtained. The observed trends in the four‐point probe conductivity measurements were correlated with the polymer structure using fourier transform infrared spectroscopy, X‐ray diffraction studies, and scanning electron microscopy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1047‐1057, 2013

Synthesis of Processable Polyaniline and its Anticorrosion Performance on 316LN Stainless Steel

The soluble polyaniline (PANI) salts were synthesized by chemical-oxidative polymerization of aniline using sodium dodecylbenzene sulfonic acid, camphor sulphonic acid and hydrochloric acid as dopants and ammonium per sulphate (APS) as an oxidant. The synthesized PANI were characterized by X-ray diffraction, scanning electron microscope, Fourier transform-infrared spectroscopy and thermogravimetric analysis. It is found that the yield of PANI, electrical conductivity, solubility and thermal stability varies with the dopants and the stoichiometrics of monomer/dopant ratios. The PANI doped sample follows the solubility order as: PANI–SDBS > PANI–CSA > PANI–HCl. Thermal stability of PANI–CSA is grater than PANI–SDBS and PANI–HCl. XRD pattern shows the higher crystallinity for HCl and CSA doped PANI while SDBS doped PANI shows the poor crystallinity. SEM study revealed the partially crystalline and agglomerated morphology of the polymer. According to the results, the corrosion rate or corrosion current of PANI–SDBS salts coated samples varies with molar ratios of SDBS to aniline and the optimum molar ratio of PANI–SDBS coating to achieve the best anticorrosive performance on 316LN SS is 2.5 mol mol−1.

Synthesis of Conducting Polyaniline Using Compound Oxidant

Conductive polyaniline (PANI) was synthesized by the oxidation of aniline with complex oxidant composed of ammonium persulfate ((NH4)2S2O8) and ascorbic acid (C6H8O6) in a reaction media containing sulfuric acid (H2SO4). The effects of concentration of H2SO4, (NH4)2S2O8 and (NH4)2S2O8/C6H8O6 mol ratio on the polymerization of aniline were studied. The optimal polymerization condition was aniline 1mol/L, H2SO4 1mol/L, and compound oxidant (mole ratio of (NH4)2S2O8 to C6H8O6 as to 10:1) 1mol/L at room temperature without the protection of N2. The conductivity and yield of PANI reach 13.3S/cm and 96.7%, respectively. The structural changes of PANI were measured by FTIR, Raman and XRD. The results indicated that PANI was some crystal and its groups took place red shift.

Chemical polymerization of aniline in phenylphosphinic acid

The chemical polymerization of aniline was performed in phenylphosphinic acid (APP) medium using ammonium peroxidisulfate as the oxidizing agent, at 0 ?C and 25 ?C. The yield of polyaniline (PANI) was about 60?69 %. The polymerization process required an induction time 8?10 times greater than in other acids (hydrochloric, sulfuric). The average density of the obtained polymer was 1.395 g cm-3 for PANI-salt and 1.203 g cm-3 for PANI-base. The acid capacity of PANI depends on the synthesis parameters and the maximum value was 15.02 meq/g polymer. The inherent viscosity of PANI was 0.662 dl/g at aniline/oxidant molar ratios >2 and 0 ?C. The oxidation state was a function of the synthesis parameters and lay between 0.553?0.625, as determined from UV-VIS and titration with TiCl3 data. The PANI samples were characterized by measurements of their density, inherent viscosity conductivity, acid capacity, FTIR and UV-VIS spectrum, and thermogravimetric data.

THE CHEMICAL SYNTHESIS OF CONDUCTIVE POLYANILINE BY USING BENZOYL PEROXIDE

ABSTRACT The chemical polymerization of aniline was carried out in acetonitrile/water media by the use of benzoyl peroxide as an initiator. Among the acids chosen as dopant the highest yield was obtained in HCl with 24.8% and the highest conductance was observed in H2SO4 with 0.082 S cm−1. The effect of HCl, benzoyl peroxide and aniline concentrations upon polyaniline yield and conductivity was also investigated. The polyaniline was characterized by conductivity measurements, UV-Vis and FTIR.

Polyaniline. Preparation of a conducting polymer(IUPAC Technical Report)

Abstract Eight persons from five institutions in different countries carried out polymerizations of aniline following the same preparation protocol. In a "standard" procedure, aniline hydrochloride was oxidized with ammonium peroxydisulfate in aqueous medium at ambient temperature. The yield of polyaniline was higher than 90 % in all cases. The electrical conductivity of polyaniline hydrochloride thus prepared was 4.4 ± 1.7 S cm-1 (average of 59 samples), measured at room temperature. A product with defined electrical properties could be obtained in various laboratories by following the same synthetic procedure. The influence of reduced reaction temperature and increased acidity of the polymerization medium on polyaniline conductivity were also addressed. The conductivity changes occurring during the storage of polyaniline were monitored. The density of polyaniline hydrochloride was 1.329 g cm-3. The average conductivity of corresponding polyaniline bases was 1.4 x10­8 S cm-1, the density being 1.245 g cm-1. Additional changes in the conductivity take place during storage. Aging is more pronounced in powders than in compressed samples. As far as aging effects are concerned, their assessment is relative. The observed reduction in the conductivity by ~10 % after more than one-year storage is large but, compared with the low conductivity of corresponding polyaniline (PANI) base, such a change is negligible. For most applications, an acceptable level of conductivity may be maintained throughout the expected lifetime.

Polyaniline Dispersions. 5. Poly(vinyl alcohol) and Poly(N-vinylpyrrolidone) as Steric Stabilizers

When the oxidative polymerization of aniline proceeds in the presence of poly(vinyl alcohol) or poly(N-vinylpyrrolidone), sterically-stabilized polyaniline dispersions are obtained. The particles have an average diameter of about 300−600 nm as determined by dynamic light scattering. The yield of polyaniline in dispersion form often decreased if the reaction mixture was stirred during polymerization and dispersions were then accompanied by a macroscopic precipitate. Poly(N-vinylpyrrolidone) is a more efficient stabilizer compared to poly(vinyl alcohol). Microstructured composites, which contain up to ∼70 wt % of electrically-conducting polyaniline dispersed in an insulating matrix, can be prepared from these dispersions.

Influence of hydrolysis on the chemical polymerization of aniline

The influence of hydrolysis on the process of oxidative polymerization of aniline was evaluated through the effect of polymerization temperature on the yield of polyaniline (PANI) in different pH regions where the polymerization took place. The synthesis parameters were chosen based on the dependence of the polymerization and hydrolysis processes on the pH of the medium, and considering the opposing thermal effects of the two processes (exothermic polymerization and endothermic hydrolysis). The yield of PANI was evaluated from the conductivity of composite films cast from aqueous dispersions of PANI prepared by chemical oxidative polymerization of aniline using poly(vinyl alcohol- co-acetate) as a steric stabilizer. It was found that the influence of hydrolysis is most pronounced in slightly acidic (pH > 4) and strongly acidic (pH < 1.5) media. This imposes the requirement for the polymerization of aniline to be carried out at low temperature (0–5°C) in order for hydrolysis to be suppressed. When the initial stage of polymerization takes place at 4 < pH < 1.5, hydrolysis does not play a significant role and polymerization proceeds with a high yield irrespective of the temperature changes.