Glucose oxidase electrodes of poly(o‐anisidine), poly(o‐toluidine), and their copolymer as biosensors: A comparative study

Thin films of poly(o‐anisidine) (POA), poly(o‐toluidine) (POT), and their copolymer poly(o‐anisidine‐co‐o‐toluidine) (POA‐co‐POT) were electropolymerized in solutions containing 0.1M monomer(s) and 1M H₂SO₄ as an electrolyte through the application of a sequential linear potential scanning rate of 50 mV/s between ?0.2 and 1.0 V versus an Ag/AgCl electrode on a platinum electrode. A simple technique was used to construct glucose sensors through the entrapment of glucose oxidase (GOD) in thin films of POA, POT, and their copolymer POA‐co‐POT, which were electrochemically deposited on a platinum plate in phosphate and acetate buffers. The maximum current response was observed for POA, POT, and POA‐co‐POT GOD electrodes at pH 5.5 and at a potential of 0.60 V (vs Ag/AgCl). The phosphate buffer yielded a fast response in comparison with the acetate buffer in amperometric measurements. The POT GOD electrode showed a fast response and was followed by POA‐co‐POT and POA GOD electrodes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1877–1884, 2004     

Electrochemical Behavior of Polyaniline,Poly(o-Anisidine) and Their Copolymer Thin Films in Inorganic and Organic Supporting Electrolytes

Abstract

The influence of inorganic and organic supporting electrolytes on electrochemical, optical, and conducting properties of polyaniline, poly(o-anisidine), and poly(aniline-co-o-anisidine) thin films were investigated. Homo- and copolymer thin films were synthesized electrochemically, under cyclic voltammetric conditions in aqueous solutions of inorganic acids, viz., H₂SO₄, HCl, HNO₃, H₃PO₄, and HClO₄ and organic acids, viz., benzoic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, and adipic acid, at room temperature. The films were characterized by cyclic voltammetry, ultraviolet (UV)–Visible spectroscopy, and conductivity measurements using four probe technique. The optical absorption spectra indicated that the formation of the conducting emeraldine salt (ES) phase took place in all the inorganic supporting electrolytes used whereas, inorganic supporting electrolytes ES phase formed only with oxalic acid. It was also observed that the current density and conductivity of thin films are greatly affected by the nature and size of the anion present in the electrolyte. The formation of copolymer has also been confirmed by differential scanning calorimetry.     

Electrochemical Synthesis and Characterization of Conducting Copolymer: Poly(o-aniline-co-o-anisidine)

Copolymerization of o-anisidine and o-anisidine was achieved electrochemically in aqueous solution containing H₂SO₄ as supporting electrolyte. The copolymer compositions can be altered by varying the monomer feed ratios during electrosynthesis. The films were electropolymerized in solution containing monomers in various ratio (0.025–0.1 M) and 1 M sulphuric acid as electrolyte by applying sequential linear potential scan rate 50 mV/s between ? 0.2 to 1.0 V. versus Ag/AgCl electrode. The copolymers were characterized by cyclic voltammetric, conductivity measurement, UV-Visible spectroscopy, FT-IR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and CHN elemental analysis.     

Synthesis and Characterization of a Conducting Composite of Polyaniline,Poly(o-Anisidine), and Poly(Aniline-co-o-Anisidine)

A conducting composite of polyaniline, poly(o-anisidine), and poly(aniline-co-o-anisidine) using incorporation of TiO₂ and SiO₂ was prepared by electrochemical polymerization. The films were electropolymerized in a solution containing 0.1 M monomer(s), 1 M sulfuric acid as supporting electrolyte, and 10^?5 M TiO₂ and SiO₂ by applying a sequential linear potential scan rate of 50 mV/s between ? 0.2 and 1.0 V versus an Ag/AgCl electrode. The composites were characterized by cyclic voltametry, UV-visible spectroscopy, electrical conductivity, and thermogravimetric analysis. It was observed that the UV-visible peaks appeared in the region of the conducting emerladine salt phase. In an overall study, the polymers prepared using TiO₂ had a higher conductivity than those prepared with SiO₂; however, higher conductivity was observed for the polyaniline-TiO₂ conducting composite than for the other polymers. The composites did not lose their color at higher temperature and hence can be utilized as the conductive pigments required for antielectrostatic applications.     

Growth Behavior of Poly(o-Anisidine-Co-Aniline) Deposition by Cyclic Voltammetry

Electrochemical copolymerization of o-anisidine (OA) with aniline (A) was carried out in 1 M H₂SO₄ by cyclic voltammetry. Polymeric films were deposited by employing different conditions such as cycle number and mole ratio of comonomers. Electrochemical homopolymerization of o-anisidine with aniline were also done. A growth equation for copolymer deposition relating parameters of operation and charge associated for film deposition was obtained. Growth rate constant was determined.     

Electrochemical Synthesis and Characterization of Poly(o-anisidine) Film with Various Dopants: A Comparative Study

In the present work, the doped (composite) films of póly(o-anisidine)–polyvinylsulphonic acid (POA-PVS), poly(o-anisidine)–toluenesulphonic acid (POA-pTS), and poly(o-anisidine)–dodecylbenzenesulphonic acid (POA-DBS) were synthesized on a platinum electrode, using electrochemical polymerization. These synthesized films were characterized by electrochemical techniques, conductivity measurement, UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The optimal film growth was achieved for synthesis of the POA film in the presence of dodecylbenzenesulphonic acid (DBS). The POA-DBS composite film exhibits good electrochemical properties, conductivity with a uniformly porous surface morphology which can be used for the immobilization of biocomponent.     

Development of a POA/DBS/GOx Biosensor for the Determination of Glucose

In the present work, a simple technique is described for constructing a poly(o-anisidine) (POA)-dodecylbenzene sulphonic acid (DBS)-glucose oxidase (GOx) (POA-DBS-GOx) electrode. The enzyme glucose oxidase (GOx) was immobilized by crosslinking via glutaraldehyde on the POA-DBS film. The POA-DBS films were synthesized electrochemically on platinum substrate. The synthesized films were characterized by using electrochemical technique, conductivity measurement, UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The conductivity of the polymer films was found to be about 7.61 × 10^?2 S/cm. The crosslinking of enzyme and the porous morphology of the polymer film lead to good stability and good response time of the enzyme electrode. The stability and lifetime of the POA-DBS-GOx electrode have been studied. It shows very good stability and response for 3–4 weeks at 4°C. The results of this study reveal that a phosphate buffer gives better response than acetate buffer in amperometric measurements.     

Electrochemical polymerization of poly(o-anisidine) thin films: effect of synthesis temperature studied by cyclic voltammetry

The effect of temperature on the electrochemical synthesis of poly(o-anisidine) (POA) thin films has been investigated. The POA films were synthesized electrochemically under cyclic voltammetric conditions in aqueous solutions of H₂SO₄ at various temperatures between -6°C and 40°C. These films were characterized by cyclic voltammetry (CV), UV–visible spectroscopy and scanning electron microscopy (SEM). It has been found that the rate of polymer formation depends on the synthesis temperature and is highest at 15°C. The optical absorption spectra indicate a major peak at about 800nm and a shoulder at about 440nm independent of the synthesis temperature. The peak at about 800nm corresponds to the presence of the emeraldine salt phase of POA, while the latter may be attributed to the formation of radical cations. The absorbance and width of the peak at about 800nm is observed to increase at low synthesis temperatures. The POA film synthesized at 15°C shows predominant formation of the emeraldine salt phase of POA. The surface morphology as revealed by SEM, is observed to depend on the synthesis temperature, and is caused by different rates of polymer formation at different temperatures. © 1998 SCI.     

Synthesis and characterization of conducting homopolymers and copolymers of o‐anisidine and o‐toluidine in inorganic and organic supporting electrolytes

The influence of inorganic and organic supporting electrolytes on the electrochemical, optical, and conducting properties of poly(o‐anisidine), poly(o‐toluidine), and poly(o‐anisidine‐co‐o‐toluidine) thin films was investigated. Homopolymer and copolymer thin films were synthesized electrochemically, under cyclic voltammetry conditions, in aqueous solutions of inorganic acids (H₂SO₄, HCl, HNO₃, H₃PO₄, and HClO₄) and organic acids (benzoic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, and adipic acid) at room temperature. The films were characterized by cyclic voltammetry, ultraviolet–visible spectroscopy, and conductivity measurements with a four‐probe technique. The ultraviolet–visible spectra were obtained ex situ in dimethyl sulfoxide. The optical absorption spectra indicated that the formation of the conducting emeraldine salt (ES) phase took place in all the inorganic electrolytes used, whereas in organic acid supporting electrolytes, ES formed only with oxalic acid. Moreover, the current density and conductivity of the thin films was greatly affected by the nature and size of the anion present in the electrolyte. For the copolymer, the conductivity lay between the conductivity of the homopolymers, regardless of the supporting electrolyte used. The formation of the copolymer was also confirmed with differential scanning colorimetry. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2634–2642, 2003     

Poly(methyl methacrylate) based nanocomposite gel polymer electrolytes with enhanced safety and performance

The study presents preparation of poly methyl methacrylate (PMMA) based nanocomposite gel polymer electrolytes consisting of, salt lithium perchlorate (LiClO₄), plasticizer PC/DEC and different proportions of SiO₂ nanofiber by solution casting process. The effect of the composition of the electrolytes on their ionic, mechanical and thermal characteristics was investigated. Morphology of the nanocomposite electrolyte films has been observed by scanning and transmission electron microscopes. Interactions among the constituents of the composite and structural changes of the base polymer were investigated by Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques. The maximum conductivity i.e. 10^?3 Scm^?1 at room temperature is obtained with the electrolyte composition of 0.6(PMMA)-0.15(PC + DEC)-0.1LiClO₄ (wt%) containing 10 wt% SiO₂ nanofiber and the temperature dependent conductivity data of the electrolyte follows Vogel-Tamman-Fulcher (VTF) behavior.     

Poly(o-anisidine) on brass: Synthesis and corrosion behavior

The electrochemical synthesis of poly(o-anisidine) (POA) was achieved on brass (CuZn) electrode by applying two scan rates (50 and 20 mVs⁻¹). The synthesized polymer films were strongly adherent and homogeneous in both cases. Their corrosion performance was investigated by AC impedance spectroscopy (EIS) technique, anodic polarization plots and open circuit potential-time curves, in 3.5% NaCl solution. It was clearly seen that poly(o-anisidine) films provided a significant physical protection for longer exposure time. It was shown that polymer film coated at high scan rate (CuZn/POA-H) exhibited better barrier property against the attack of corrosive agents when compared with polymer film obtained at low scan rate (CuZn/POA-L). It was found out that poly(o-anisidine) film synthesized at high scan rate caused a significant increase in corrosion resistance by its catalytic behavior on formation of protective oxide layers on the surface in longer time.     

Enhanced thermoelectric properties of poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate)/copper phthalocyanine disulfonic acid composite films

A series of poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)/copper phthalocyanine disulfonic acid (PEDOT: PSS/CuPc-[SO₃H]₂) composite films were prepared by using CuPc-(SO₃H)₂ as the dopant. EG treatment was applied to further improve the thermoelectric properties of PEDOT: PSS/CuPc-(SO₃H)₂ composites. Structural analyses indicated the strong π − π interactions existed between PEDOT: PSS and CuPc-(SO₃H)₂, and led to more ordered regions in the composite films, and benefit the conductivity. CuPc-(SO₃H)₂ can greatly improve the thermoelectric properties of PEDOT: PSS/CuPc-(SO₃H)₂ composite films, which have a Seebeck coefficient of 13.2 μV K⁻¹ and a conductivity of 2.8 × 10⁵ S/m with 20 wt% CuPc-(SO₃H)₂ at room temperature, and the corresponding power factor is 48.8 μW m⁻¹ K⁻², which is almost 6.83 times higher than the PEDOT: PSS films without CuPc-(SO₃H)₂.     

Ionic interactions and transport characteristics of a new polymer electrolyte system containing poly(propylene glycol) 4000 complexed with AgCF3SO3

The effect of concentration of AgCF₃SO₃ salt on the behavior of ionic transport within the polymer electrolyte system containing the polymer host poly(propylene glycol) of molecular weight 4000 (PPG4000) has been investigated in terms of spectroscopic and electrochemical properties. It is evident that the presence of well-defined interactions between the ether oxygens and silver cations arising due to the complexation of the silver salt with the polymer matrix has enabled the chosen polymer electrolyte system to possess the maximum room temperature (298 K) electrical conductivity of 9.4 × 10^?5 S cm^?1 in the case of the typical composition having the ether oxygen-to-metal ratio (O:M) of 4:1 and the lowest activation energy E _a of 0.46 eV for Ag⁺ ionic conduction.     

Effective influences of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIMTFSI) ionic liquid on the ion transport properties of micro-porous zinc-ion conducting poly (vinyl chloride) /poly (ethyl methacrylate) blend-based polymer electrolytes

A series of new gel polymer electrolytes (GPEs) based on different concentrations of a hydrophobic ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIMTFSI) entrapped in an optimized typical composition of polymer blend-salt matrix [poly(vinyl chloride) (PVC) (30 wt%) / poly(ethyl methacrylate) (PEMA) (70 wt%) : 30 wt% zinc triflate Zn(CF₃SO₃)₂] has been prepared using facile solution casting technique. The AC impedance analysis has revealed the occurrence of the maximum ionic conductivity of 1.10 × 10^?4 Scm^?1 at room temperature (301 K) exhibited by the PVC/PEMA- Zn(OTf)₂ system containing 80 wt% ionic liquid. The addition of EMIMTFSI into the optimized PVC/PEMA- Zn(OTf)₂ system in different weight percentages enhances the number of free zinc ions thereby leading to enrichment of ionic conductivity. The structural and complexation behaviour of the as prepared polymer gel electrolytes was substantiated by subjecting these electrolyte films to X-ray diffraction (XRD) and Attenuated total reflectance - Fourier transformed infrared (ATR-FTIR) investigations. The wider electrochemical stability window ~ 3.23 V and a reasonable cationic transference number (t_Zn ²⁺) of 0.63 have been attained for the polymer gel electrolyte film containing higher loading of (80 wt%) ionic liquid. The development of the amorphous phase of these gel polymer electrolyte membranes with increasing ionic liquid content was observed from scanning electron microscopic (SEM) analysis. The results of the current work divulge the assurance of developing GPEs based on ionic liquids for prospective application in zinc battery systems.     

Optical,Electrochemical, and Structural Properties of Spray Coated Dihexyl Substituted Poly (3,4 Propylene Dioxythiophene) Film for Optoelectronics Devices

The dihexyl substituted poly (3,4-propylenedioxythiophene) (PProDOT-Hx₂) thin films uniformly deposited by cost effective spray coating technique on transparent conducting oxide coated substrates. The electro-optical properties of PProDOT-Hx₂ films were studied by UV-Vis spectroscopy that shows the color contrast about 45% with coloration efficiency of ～ 185 cm²/C. The electrochemical properties of PProDOT-Hx₂ films were studied by cyclic voltammetry and AC impedance techniques. The cyclic voltammogram shows that redox reaction of films are diffusion controlled and ions transportation will be faster on the polymer film at higher scan rate. Impedance spectra indicate that polymer films are showing interface charge transfer process as well as capacitive behavior between the electrode and electrolyte. The XRD of the PProDOT-Hx₂ thin films revealed that the films are in amorphous nature, which accelerates the transportation of ions during redox process.     

Spectroelectrochemical behaviour of poly (3-octylthiophene): application to electrochromic windows with polyaniline and iridium oxide

The spectroelectrochemical behaviour of cast poly(3-octylthiophene) (POT) films (0.2 and 0.5 m) on indium-tin-oxide (ITO) glass electrodes has been investigated in organic media. These thin films exhibit interesting electrochromic properties and their application in electrochromic devices has been examined in liquid (CH₃CN + LiClO₄ 0.3 M) and viscous electrolyte (PEO + CH₃CH + LiClO₄). Polyaniline (PANI) film appears to be a convenient complementary counter electrode since its transmission maximum corresponds to its oxidized state and that of POT film to its reduced state. Thin films of iridium oxide (IrO₂) are also possible counter electrodes, even in acetonitrile, the electrochemical behaviour being mostly capacitive with a low transmission change. However, the best contrast is obtained with the POT/PANI system.     

Preparation and characterization of a solid polymer electrolyte PEO‐ENR50 (80/20)‐LiCF3SO3

The preparation and characterization of a polymer electrolyte films containing 80 wt % of poly (ethylene oxide) (PEO) and 20 wt % epoxidized natural rubber (ENR50) complexed with LiCF₃SO₃ has been reported. The ac impedance data showed good conducting properties of the solid polymer electrolyte (SPE) films. The greatest room temperature ionic conductivity of 7.5 × 10^?5 S cm^?1 was obtained at 25 wt % of LiCF₃SO₃ salt. This result has been supported by differential scanning calorimeter and X‐ray diffraction analysis. Analysis differential scanning calorimetry showed the relative percentage of crystallinity and T_m of PEO decreased with the increasing wt % of LiCF₃SO₃. Analysis with X‐ray diffraction suggested that the semicrystalline nature of PEO turned to amorphous due to the presence of LiCF₃SO₃. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Poly(O‐methoxyaniline) thin films: Cyclic voltammetry study

Electrochemical polymerization of poly(O‐methoxyaniline) (POMA) thin films was carried out under cyclic voltammetric conditions. The cyclic voltammograms (CV) of the POMA films in the presence and absence of monomer in the aqueous solution of 1M H₂SO₄ were studied. The electrochemical degradation of the POMA films was investigated by cyclic voltammetry and UV‐visible spectroscopy. It was observed that the rate of degradation is strongly dependent on the applied potential. UV‐visible spectroscopy revealed no significant chemical modification or phase change from the degradation. The temperature dependence of the voltammetric response of the POMA films in the aqueous solution of 1M H₂SO₄ was also investigated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3009–3015, 1999     

Optimization of preparation conditions on the dielectric properties of polyaniline

The dielectric response in the microwave field of polyaniline prepared at different temperatures and using different inorganic and organic dopants was studied. Chemical oxidative polymerization of aniline was done at low temperature (0–5°C), at room temperature, and at high (60°C) temperature using different inorganic dopants like HCl, HNO₃, H₂SO₄, HClO₄, etc. Polyaniline was also prepared with different organic dopants like camphor sulfonic acid, Toluene sulfonic acid, and Naphthalene sulfonic acid. All polymers formed were characterized using IR, TGA, DSC, and SEM, etc. The dielectric responses of all polymers are studied using cavity perturbation technique in the microwave field. The studies indicates that the polyaniline prepared with perchloric acid at room temperature shows higher conductivity and absorption coefficient compared with all other samples. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009