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Preparation and characterization of multilayer Systems consisting of the soluble and electrochemically synthesized polypyrrole films
Abstract
A multilayer system consisting of the soluble and electrochemically synthesized PPy films has been prepared for investigation of the application possibility of soluble PPy film as an intermediate layer between the non-conducting substrate and electrochemically synthesized PPy film. Soluble PPy has been synthesized by chemical oxidative polymerization. A glass substrate with deposited soluble PPy film was used as anode for electrochemical polymerization of pyrrole. Resulting multilayer system has been characterized by cyclic voltammetry technique (CV). Surface morphology of PPy films was characterized with Scanning Electron Microscopy (SEM). The synthesized soluble PPy, was characterized by IR and UV-Vis spectroscopy.
Conducting polymers (CPs) characteristically form polarons, bipolarons, or solitons and exhibit low band-gap energies. These properties make them to be suitable materials for applications in sensors, semiconductors, anticorrosion coatings, batteries, and display devices, among others. This chapter focuses on the electronics, electrochemistry, and processability of some commonly used CPs in the recent past – namely, polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh), poly(3,4-ethylenedioxythiophene) (PEDOT), and polyfuran (PFu). Also included in the chapter are conducting dendritic star copolymers and polymeric nanocomposites incorporating single-walled and multiwalled carbon nanotubes.
The Ppy–PVS-GOD biosensor for determination of glucose has been described. The enzyme, glucose oxidase (GOD) was immobilised by cross-linking via glutaraldehyde on a polypyrrole–polyvinyl sulphonate (Ppy–PVS) composite film. The Ppy–PVS film was electrochemically synthesized on indium–tin-oxide (ITO)-coated glass plate. We have synthesized Ppy–PVS film with 0.1M pyrrole, 0.025M PVS at 3.0 pH and 1mA/cm2 current density. The immobilization was done by cross-linking 2mg/ml GOD via 0.1% glutaraldehyde at 0.1M phosphate buffer with 7.0 pH. The synthesized composite films were characterized using galvanostatic electrochemical technique, electrical conductivity, UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The cross-linking of enzyme and porous morphology of the polymer film leads to high enzyme loading and an increase in lifetime, stability and fast response time of the enzyme electrode. Amperometric response was measured as a function of different concentration of glucose. It was observed that current increases with increasing glucose concentration in the range 1–50mM.
The Polypyrrole-polyvinylsulphonate-glucose oxidase (Ppy–PVS–GOD) biosensor for determination of glucose has been described in the present investigation. The enzyme, glucose oxidase (GOD) was immobilized by crosslinking via glutaraldehyde on a polypyrrole–polyvinyl sulphonate (Ppy–PVS) composite film. The Ppy–PVS film was electrochemically synthesized on indium-tin-oxide (ITO)–coated glass plate. The synthesized composite films were characterized using galvanostatic electrochemical technique, electrical conductivity, UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The crosslinking of enzyme and porous morphology of the polymer film leads to high enzyme loading and an increase in lifetime, stability, and fast response time of the enzyme electrode. Characterization of resulting amperometric biosensor for the estimation of glucose has been experimentally determined in terms of linear response range, optimum pH, applied potential, and shelf-life. These Ppy–PVS–GOD electrodes can be used for glucose estimation from 1 to 50 mM and have a shelf-life of about 5–6 weeks at 4°C. The sensitivity of Ppy–PVS–GOD electrode in phosphate and acetate buffer has been studied. It was found that the phosphate buffer gives fast response as compared to acetate buffer in amperometric measurements.
Composite films of polypyrrole-poly(vinyl sulphonic acid) (Ppy-PVS), polypyrrole-p-toluene sulphonic acid (Ppy-pTS) and polypyrrole-dodecylbenzene sulphonic acid (Ppy-DBS) were synthesized on ITO coated glass, using electrochemical polymerization. The synthesized films were characterized using electrochemical technique, electrical conductivity, UV-Vis spectroscopy, FTIR spectra, and scanning electron microscopy (SEM). This study reveals that Ppy-PVS composite films provide a polymer matrix with very good mechanical and environmental stability, uniform surface morphology, and higher conductivity, which are suitable for the immobilization of biocomponent.
The electrochemically synthesized Polypyrrole-Polyvinyl Sulphonate (Ppy-PVS), Poly(N-methylpyrrole) - Polyvinyl Sulphonate (P(NMP)-PVS) and their co-polymer Polypyrrole-Poly(N-methylpyrrole)-Polyvinyl Sulphonate (Ppy-P(NMP)-PVS) films on indium tin oxide (ITO) coated glass electrode have been investigated by galvanostatic method. This study reveals that as compared to (P(NMP)-PVS) and (Ppy-P(NMP)-PVS), the Ppy-PVS film provide a polymer matrix with very good porosity, mechanical and environmental stability, uniform surface morphology and higher conductivity, which is suitable for the immobilization of biocomponent. The synthesized films were characterized using electrochemical technique, electrical conductivity, Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM).
A series of freestanding conducting polypyrrole and poly‐3‐methylthiophene films was prepared and examined by x‐ray diffraction
and transmission electron microscopy (TEM). The degree of order observed in polypyrroles was highly dependent upon the incorporated
“dopant” anions and also on deposition conditions. Examination of a large variety of dopant systems showed that substituted
benzenesulfonate and long aliphatic chain monoanions imparted the highest order, and chemically prepared polypyrroles were
less ordered than their electrochemical counterparts. Doped poly‐3‐methylthiophene exhibited comparable order, yet was less
flexible in its ability to incorporate large dopant anions. Crystalline phases were detected by electron diffraction in some
polymer systems.
Polypyrrole soluble in m-cresol and conditionally soluble in chloroform, dichloromethane or 1,1,2,2-tetrachloroethane was synthesized chemically by using dodecylbenzene sulfonic acid as the dopant and ammonium persulfate as the oxidant. The polymer was soluble in m-cresol and became soluble in the weakly poor solvents such as chloroform, dichloromethane and 1,1,2,2-tetrachloroethane when equal amounts of dodecylbenzene sulfonic acid and polymer were added to one of the solvents. Soluble polypyrrole showed the same spectra of FT-Raman scattering and UV-Vis light absorption as those of electrochemically polymerized polypyrrole. The intrinsic viscosity of the soluble polypyrrole in m-cresol was 0.17 dl/g. The solution of the polymer in chloroform was cast to a stiff film with a very smooth surface and the electrical conductivity of the film was 5 S/cm. The redox reactivity of the film was sustained for a long time in cyclovoltammetry.