Matrix electropolymerized

Chen X, Hu Y, Wilson GS. Glucose microbiosensor based on alumina sol-gel matrix/ electropolymerized composite membrane. Biosensors Bioelectronics 2002, 17, 1005-1013. 

The above principle was used in the design of a selective layer for detection of HCN. It is based on a polyaniline (PANI) matrix electropolymerized on a Pt electrode. Metal clusters of Hg or Ag are formed by the spontaneous decrease of WF as discussed above. A typical response of the oxidized PANPHg layer to step-change of HCN concentration from 0 to 19.3 ppm is shown in Figure 10.8. 

Conduction in the raw doped polymer can be improved by devices such as compression and stretching and judicious after-synthesis dopant ion exchange. Matrix-guided electropolymerization also yields superior products. 

For consistent and reproducible operation it is important to control chemosensor features like thickness of the MIP coatings. Generally, MIPs were prepared and immobilized on PZ resonators by using two distinct procedures, namely in situ assembling on the resonator surface [103] or physical entrapment of the preprepared MIP particles in an inert polymer matrix attached to this surface [21]. Typically, thickness of the polymer is 20 nm to 5 pm. In situ immobilization of MIPs (see below in Sects. 3.2.1-3.2.4) can be accomplished by surface grafting, sandwich casting, electropolymerization, physical entrapment or chemical coupling [102],... 

M thiocyanate solution. The lifetime of these electropolymerized electrodes (at least 2 months) is a significant improvement over that of PVC-based electrodes that use cobalt porphyrins (28, 29). The latter electrodes were selective toward thiocyanate, but the slopes of the calibration curves deteriorated substantially in less than one month. The improved lifetimes of the poly[Co(o-NH2)TPP] electrodes may be attributed to the covalent fixation of the ionophore to the polymeric matrix ... 

Suspensions of polypyrrole were prepared by the FeCls oxidation of pyrrole in an aqueous solution of methylcellulose (49). The product was dried and yielded films with conductivities of 0.2 S/cm. Scanning electron microscopy revealed globular polypyrrole embedded in the methylcellulose matrix. After several months, these suspensions remained stable with no detectable precipitation. Similarly, the electropolymerization of 3-methyl-thiophene in solutions of poly(methyl methacrylate) and poly(vinyl chloride) was reported (50, 51). 

Composites of polypyrrole and poly(vinyl chloride) have been prepared by several groups (64-67). Polythiophene-poly(vinyl chloride) composites have also been prepared (68). The electropolymerization of pyrrole on poly(vinyl chloride)-coated electrodes yielded composites with mechanical properties (tensile strength, percent elongation at break, percent elongation at yield) similar to poly(vinyl chloride) (65) but with a conductivity of 5-50 S/cm, which is only slightly inferior to polypyrrole (30-60 S/cm) prepared under similar conditions. In addition, the environmental stability was enhanced. Morphological studies (69) showed that the polypyrrole was not uniformly distributed in the film and had polypyrrole-rich layers next to the electrode. Similarly, poly(vinyl alcohol) (70) poly[(vinylidine chloride)-co-(trifluoroethylene)] (69) and brominated poly(vinyl carbazole) (71) have been used as the matrix polymers. The chemical polymerization of pyrrole in a poly(vinyl alcohol) matrix by ferric chloride and potassium ferricyanide also yielded conducting composites with conductivities of 10 S/cm (72-74). 

Electronic matrix element 6 Electron transfer 312 Electroorganic reaction 329 Electroosmosis 268 Electrooxidation 79 Electropolymerization 102... 

Ultrasound was also used for the dispersion of a surfactant pyrrole, prior to electrooxidation to the conducting polymer [233]. An amphiphilic (pyrrolylalkyl) ammonium monomer dispersion was used to coat the electrode surface with monomer, subsequently electropolymerized to thin films using an aqueous electrolyte for this step. Ultrasound has also been used to assist impregnation of pyrrole monomer into, for example, a conventional polymer matrix prior to polymerization to yield a composite of the conducting and conventional polymers, but is also a pretreatment effect of ultrasound rather than a sonoelectrochemical one [234],... 

FIGURE 3.5 A matrix formed by electropolymerizing pyrrole using human red blood cells and poly(vinyl sulfate) as dopant anion (using a current density of 0.5 mAcm 2 for 10 sec). 

Li+ salts with conservation of the rotaxanated topography. This was proved when Cu1 was nearly quantitatively reincorporated into the polyrotaxane. An X-ray absorption spectroscopy (XAS) study confirmed that the Cu1 is in a similar environment to model compounds, but that the symmetry of the coordination sphere is reduced due to steric constraints of the polymer matrix.71 Attempts to replace Cu1 with Co11 or Zn11 using the Li+ intermediate, or by electropolymerizing rotaxane 93 with Co11 or Zn11 in the place of Cu1 failed.72... 

The electropolymerization process and the incorporation of the metallic macrocycle into the polymer matrix can be followed in situ by spectroscopic techniques. 

In this work, we describe the synthesis and characterization of SWNT/PANI composite films with SWNT incorporated into PANI matrix via electrochemical composite codeposition technique during electropolymerization. The SWNT/PANI composite film modified by electrochemically depositing platinum subsequently shows much higher mass activity and long-term stability for formaldehyde oxidation than a pure PANI film. 

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