Poly electropolymerization

Flavin adenine dinucleotide (FAD) has been electropolymerized using cyclic voltammetry. Cyclic voltammograms of poly (FAD) modified electrode were demonstrated dramatic anodic current increasing when the electrolyte solution contained NADH compare with the absence of pyridine nucleotide. 

This means that we can follow the empirical kinetics of the electropolymerization process, at a constant overpotential (Fig. 6), by tracking the weight of the rinsed and dried polymer film,37 41 as we do in homogeneous polymerization processes of conducting or nonconducting poly-... 

In the field of soluble conducting polymers new data have been published on poly(3-alkylthiophenes " l They show that the solubility of undoped polymers increases with increasing chain length of the substituent in the order n-butyl > ethyl methyl. But, on the other hand, it has turned out that in the doped state the electro-chemically synthesized polymers cannot be dissolved in reasonable concentrations In a very recent paper Feldhues et al. have reported that some poly(3-alkoxythio-phenes) electropolymerized under special experimental conditions are completely soluble in dipolar aprotic solvents in both the undoped and doped states. The molecular weights were determined in the undoped state by a combination of gel-permeation chromatography (GPC), mass spectroscopy and UV/VIS spectroscopy. It was established that the usual chain length of soluble poly(3-methoxthythiophene) consists of six monomer units. 

Fig. 2. Curve A Eleotropolymerization of ImH H2(o-NH2)TPP in 0.1M Et NClO /CH CN by sweeping potential at 200mV/s on Pt electrode. Numbers represent scan number. Curve B Cyclic voltammogram of an electropolymerized film of poly-[H2(o-NH2)TPP] on a Pt electrode, in 0.1M Et NClO /CH CN at 200 mV/s. Integration of the charge under the wave shows that coverage is 3.5X10 9 mol/cm of the porphyrin sites. Curve C Rotated disk electrode voltammetry of the Os(lII,Il) reaction for 0.2 mM...

Polymeric films of [(//5-C s Me5)M(L)Cl]+complexes (M = Ir, Rh L = pyrrole-substituted bpy or phen) have been coated on an electrode by oxidative electropolymerization. The buildup of hydrido complexes in films is well known 27,28,30 the high electrocatalytic activity of these molecular electrode materials towards dihydrogen evolution in organic and aqueous electrolytes is also well known.25,31 For example, H2 is evolved at —0.55 V vs. SCE at a poly [(j75-C5Me5)-Rh(bpy)Cl]+ film in pH 1 aqueous solution.31... 

C. Malitesta, F. Palmisano, L. Torsi, and P. Zambonin, Glucose fast-response amperometric sensor based on glucose oxidase immobilized in an electropolymerized poly(o-phenylenediamine) film. Anal. Chem. 

Conductive polymers have attracted increasing attention because they have wide applications. Recently, very stable poly(thiophenes) with polyfluorinated side chains have been electrochemically synthesized and characterized [81]. Furthermore, notably novel conductive materials have been prepared by cathodic electropolymerization of perfluoro cvclobutene and cyclopentene [82]. 

Several approaches have been undertaken to construct redox active polymermodified electrodes containing such rhodium complexes as mediators. Beley [70] and Cosnier [71] used the electropolymerization of pyrrole-linked rhodium complexes for their fixation at the electrode surface. An effective system for the formation of 1,4-NADH from NAD+ applied a poly-Rh(terpy-py)2 + (terpy = terpyridine py = pyrrole) modified reticulated vitreous carbon electrode [70]. In the presence of liver alcohol dehydrogenase as production enzyme, cyclohexanone was transformed to cyclohexanol with a turnover number of 113 in 31 h. However, the current efficiency was rather small. The films which are obtained by electropolymerization of the pyrrole-linked rhodium complexes do not swell. Therefore, the reaction between the substrate, for example NAD+, and the reduced redox catalyst mostly takes place at the film/solution interface. To obtain a water-swellable film, which allows the easy penetration of the substrate into the film and thus renders the reaction layer larger, we used a different approach. Water-soluble copolymers of substituted vinylbipyridine rhodium complexes with N-vinylpyrrolidone, like 11 and 12, were synthesized chemically and then fixed to the surface of a graphite electrode by /-irradiation. The polymer films obtained swell very well in aqueous... 

Fig. 3 Regioregular poly [3-(2-methyl-1 -butoxy)-4-methylthiophene] (PMBMT) synthesized via oxidative electropolymerization...

As described in Section 3 of Chapter 4, the stabilization of n-Si electrode by coating with poly(pyrrole) has attracted much attention. The stabilization of a small bandgap n-semiconductor electrode against oxidation is of great value not only to convert visible light into chemical energy, but also to construct liquid-junction solar cells operated under visible irradiation. The poly(pyrrole) film is usually electropolymerized on the semiconductor electrode dipped in the aqueous solution of pyrrole. The remarkable stabilizing effect of poly(pyrrole) film on polycrystalline n-Si is shown in Fig. 22 67). The photocurrent obtained under irradiation in the aqueous solution of... 

Figure 9 An illustration depicting the two methods of interface passivation used here, (a) Reaction (5) alone is inhibited by electropolymerizing a film of insulating PPO, polytp-henyleneoxide-co-2-allylphenyleneoxide), on the Sn02 substrate, (b) Both reactions (4) and (5) are inhibited by coating exposed oxide surfaces with poly(methylsiloxane).

A similar process has been used to make polypyrrole-poly(vinyl alcohol) composites by electropolymerization from aqueous solution into a cross-linked poly(vinyl alcohol) film301 . The conductivity decreased and the elongation to break increased 10x with respect to polypyrrole. A conducting composite of 6% polypyrrole in a vinyl-idenefluoride-trifluorethylene copolymer showed an extension to break of 120% 302). 

Lacaze and co-workers974 have prepared poly(pr ra-phenylene) films by electropolymerization of benzene in strong acidic media including triflic acid and... 

Molecular imprinting has been used to devise a chemosensor for L-nicotine (Table 6) [178]. For that, poly(methacrylic acid) (PMA) beads, imprinted with the L-nicotine template in chloroform, were incorporated in a film of the conjugated polymer, OCiC10-PPV. EIS has then been utilized for the L-nicotine determination in the 1-10 nM concentration range. This MIP chemosensor showed predominant affinity towards L-nicotine over a structurally related L-nicotine metabolite, L-cotinine. Similarly, the polydopamine-imprinted film prepared by electropolymerization in the phosphate buffer (pH = 7.4) has been used to devise a chemosensor for L-nicotine with LOD of 0.5 pM (Table 6) [106]. This LOD is still much higher than that reported for other L-nicotine determination methods based on MIPs, such as SPE combined with differential pulsed elution, which was 6 nM [31]. 

An alkaloid pain reliever, morphine, is an often abused drug. Chronoampero-metric MIP chemosensors have been devised for its determination [204]. In these chemosensors, a poly(3,4-ethylenedioxythiophene) (PEDOT) film was deposited by electropolymerization in ACN onto an ITO electrode in the presence of the morphine template to serve as the sensing element [204], Electrocatalytic current of morphine oxidation has been measured at 0.75 V vs AglAgCllKClsat (pH = 5.0) as the detection signal. A linear dependence of the measured steady-state current on the morphine concentration extended over the range of 0.1-1 mM with LOD for morphine of 0.2 mM. The chemosensor successfully discriminated morphine and its codeine analogue. Furthermore, a microfluidic MIP system combined with the chronoamperometric transduction has been devised for the determination of morphine [182] with appreciable LOD for morphine of 0.01 mM at a flow rate of 92.3 pL min-1 (Table 6). 

An imprinted poly[tetra(o-aminophenyl)porphyrin] film, deposited on a carbon fibre microelectrode by electropolymerization, was used for selective determination of dopamine [208] in the potential range of —0.15 to 1.0 V. This chemosensor has been used successfully for dopamine determination in brain tissue samples. The dopamine linear concentration range extended from 10 6 to 10-4 M with LOD of 0.3 pM. However, this LOD value is very high compared to that of the dopamine voltammetric detection using polyaminophenol MIPs prepared by electropolymerization [209]. Dopamine was determined by CV and DPV at concentrations ranging from 2 x 10 s to 0.25 x 10 6 M with LOD of 1.98 nM. This LOD value is lower than that of PM dopamine detection [133]. 

R. Garjonyte and A. Malinauskas, Glucose biosensor based on glucose oxidase immobilized in electropolymerized polypyrrole and poly(o-phe-nylenediammine) films on a Prussian blue-modified electrode, Sens. Actuators B, 63 (2000) 122-128. 

Perform galvanostatic electropolymerization of aniline on the GC disk electrode by applying a constant current of + 0.014 mA (0.2mA/cm2) for 714 s. The electropolymerization conditions are similar to those used for poly(3,4-ethylenedioxythiophene) (see Procedure 4) and were found to give well-functioning sensors for this particular application, so therefore no further optimization was done. 

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