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A bilayer structure usually consists of two different films deposited on a substrate, one overlying the other. A typical system consists of a Pt substrate with an electro-deposited film of poly-[Ru(vbpy)3 ] on which a film of poly-[Os(bpy)2(vbpy)2" ] is elec-trodeposited (25). Another type of sandwich structure involves a pair of closely spaced electrodes such as in an electrode array (26), bridged by a polymer film. Alternatively, a different polymer can be deposited on each electrode of an array pair to form a bilayerlike arrangement having a junction where the films meet. Three-electrode devices of this type can produce a structure functionally equivalent to a field effect transistor (FET) (27). 

The sensitivity of film viscoelastic properties to the ambient medium applies not only to the solvent but also to the electrolyte. This is illustrated for the case of poly[Os(bipy)2Cl(PVP)io] (where... 

The simple models of intercalation thermodynamics have been found adequate for lithium intercalation in LixMogScg [65], lithium intercalation in Li,TiS2 [66] and CIOJ intercalation in poly(Os(bpy)2(vpy)2) [67]. The... 

This technique has revealed the potential dependency of the d.c. conductivity of poly[Os(bpy)2(vpy)2](C104)jt (x = 0-3) (bpy = 2,2 -bipyridine and vpy = 4-vinylpyr-idine) (13) [17,18]. Conductivity of 13 maximizes at three mixed valence states but the values are different... 

FIGURE 9.24 Analysis of ultrahigh poly(ethylene oxide), MW about 37 million. Eluent O.OS M NaNOj. Flow rate 0.3 ml/min. Columns PSS Suprema 20 /tim, 30000, 8 x 300 mm. Oven temp 30°C. Detector Rl. Standards PSS PEO standards. 

Kenausis G, Taylor C, Katakis I, Heller A. 1996. Wiring of glucose oxidase and lactate oxidase within a hydrogel made with poly(vinyl pyridine) complexed with [Os(4,4 -dimethoxy-2,2 -bipyridine)2Cl]. J Chem Soc Faraday Trans 92 4131-4136. 

Characterization. The series of poly(alkyl/arylphosphazenes) (1-6) was studied by a variety of standard dilute solution techniques including viscosity measurements, membrane os-... 

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...

Many of these systems employ charged polymers or polyelectrolytes that confer on them particular properties due to the existence of electrical charges in the polymer structure. Oyama and Anson [14,15] introduced polyelectrolytes at electrode surfaces by using poly(vinylpiridine), PVP, and poly-(acrylonitrile) to coordinate metal complexes via the pyridines or nitrile groups pending from the polymer backbone. Thomas Meyer s group at North Carolina [16, 17[ also employed poly(vinylpyridine) to coordinate Ru, Os, Re and other transition-metal complexes by generating an open coordination site on the precursor-metal complex. 

Figure 2.4 Redox-active building blocks used in LbL self-assembly. PAH-Os Osmium pyridil-bipyridil modified poly(allylamine) [28,58, 69, 72, 148, 150-154, 184, 185, 191, 203-205] ...

PVP-Os Osmium-bipyridyl-modified quaternized poly 4-vinylpyridine) [102,206,207] PAH-Fc Ferrocene-modified polyallylamine [77, 101, 208] P(CM-FcJ Poly(vynil ferrocene) copolymer [224] PVn Polyalkylviologens (PVn, n number of methylene groups) [67, 104,... 

Figure 2.5 Schematic representation of the Au/MPS/PAH-Os/solution interface modeled in Refs. [118-120] using the molecular theory for modified polyelectrolyte electrodes described in Section 2.5. The red arrows indicate the chemical equilibria considered by the theory. The redox polymer, PAH-Os (see Figure 2.4), is divided into the poly(allyl-amine) backbone (depicted as blue and light blue solid lines) and the pyridine-bipyridine osmium complexes. Each osmium complex is in redox equilibrium with the gold substrate and, dependingon its potential, can be in an oxidized Os(lll) (red spheres) or in a reduced Os(ll) (blue sphere) state. The allyl-amine units can be in a positively charged protonated state (plus signs on the polymer...

Nitrite sensor Osmium-bipyridyl-modified quaternized poly(4-vinylpyri-dine) (PVP-Os) PSS or poly[aniline-co-N- (3-sulfopropyl)aniline (PAPSH) [206]... 

The boundary between cases I-II has been explored by Flexer et al. [69] with LbL self-assembled GOx multilayers and poly(bipyridine-pyridine) redox polymer (PAH-Os). Figure 2.29 shows the catalytic response in excess glucose as a function of the number ofself-assembled polymer-enzyme bilayers. For the first bilayers (thin films)... 

For example, the small scale of the device was intended as a demonstration of architecture suitable for implanted applications. Mano et al. demonstrated a miniature fuel cell with bilirubin oxidase at the cathode catalyst that is more active at pH 7 and tolerates higher halide concentrations than does laccase. Additionally, the long-side-chain poly-(vinylpyridine)—Os(dialkyl-bis-imidazole)3 redox polymer discussed above was employed to both lower the anode potential and, via the long side chains, enhance electron transport from the biocatalyst. The cell achieved a current density of 830 at 0.52 V... 

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