Complex film

Polyelectrolyte complexes composed of various weight ratios of chitosan and hyaluronic acid were found to swell rapidly, reaching equilibrium within 30 min, and exhibited relatively high swelling ratios of 250-325% at room temperature. The swelling ratio increased when the pH of the buffer was below pH 6, as a result of the dissociation of the ionic bonds, and with increments of temperature. Therefore, the swelling ratios of the films were pH-and temperature-dependent. The amount of free water in the complex films increased with increasing chitosan content up to 64% free water, with an additional bound-water content of over 12% [29]. 

The common concentration of a surfactant used in a formulation varies from 0.05 to 0.5% and depends on the surfactant type and the solids content of the dispersion. In practice, very often combinations of surfactants rather than single agents are used to prepare and stabilize disperse systems. The combination of a more hydrophilic surfactant with a more hydrophobic surfactant leads to the formation of a complex film at the interface. A good example for such a surfactant pair is the Tween-Span system of Atlas-ICI [71]. 

There is an increasing interest in the development of electrochemical sensors and microsensors for detecting and monitoring NO or N02, due to their importance in clinical and environmental analysis. It has been suggested that transition metal electrocatalysts active for NO or N02 coordination and reduction could be exploited for the development of metal-complex film electrodes for N02 and NO sensing. However, most of the sensory devices reported so... 

L.W. Wang and N.F Hu, Electrochemistry and electrocatalysis with myoglobin in biomembrane-like DHP-PDDA polyelectrolyte-surfactant complex films. J. Colloid Interface Sci. 236, 166—172 (2001). 

Cationic ions and polyelectrolytes can stabilize the formation of the PS I monolayers at the air-water interface. These complex monolayers can be transferred onto the hydrophobic substrate surfaces by horizontal lifting method. The PS I/polyelectrolyte complex film may be used for the development of a biosystem for the studies on photoinduced electron transfer and for hydrogen evolution. 

Figure 25. Schematic models of spacer effect of polymer main chain on molecular ordering of polyion complex films.

Spectral change of polyion complex films due to thermal and photochemical phase transition. 

Figure 27. Polymer effect on isothermal spectral transition induced by moisture treatment of polyion complex films, (relative humidity = 62%)...

The moisture induced isothermal transition are also observed in the complex films. The speed of the isothermal transition are also strongly dependent on the chemical structure of the counterpart polymer (Figure 27). For example, the J-aggregate in the complex film with polymer 2 is more stable than in the original cast film without polymer. 

Photochemically induced phase transition is also found in the polyion complex films. Transient behavior of the cis isomer formation is more apparent in the complex films with polymer 6 and 7. 

Figure 28. Spectral change of annealed polyion complex films of CgAzoCioN+ Br by photoirradiation, (a) with polymer 7, (b) with polymer 6.

Photochemical switching of the phase transition is also found in the polyion complex film. Figure 29 shows reversible cycles of the absorption at 370nm by the coupling of the thermal and photoinduced phase transition of the complex film with carboxymethylcellulose 8. In conclusion, we indicate that the immobilized bilayer membranes containing the azobenzene chromophore are available to the erasable memory materials based on the phase transition triggered by thermal and photochemical processes. The polyion complex technique is clearly shown to be a very useful method for materialization of the immobilized bilayer membranes. 

Figure 29. Reversible cycles of spectral change of polyion complex film by coupling of heating (higher absorbance) and photoirradiation (lower absorbance). 

New Photodiode Composed of a Polymer-metal Complex Film... 

An anisotropic photoinduced electron flow is important to produce an efficient photocurrent. The anisotropic arrangement of the reaction components is necessary for that purpose. Polymer materials are very useful to achieve such arrangement. The arrangement of Ru(bpy)j+ and MV2+ was attained by coating electrode at first with a polymer pendant Ru complex film and then with a polymer pendant MV2+ (28) film. The photocurrent induced by this bilayer coating system is shown in... 

Title Hydrophobic Fluorinated Polyelectrolyte Complex Films and Associated Methods... 

In all the cases of poly acetylene, polythiophene, and polypyrrole coating, the amount of plasma-film deposition was different, caused by the difference in the structure of the three different monomers and their reactivity during the plasma process. PPy- and PTh-silica are more hydrophobic than PA-silica, probably due to the presence of different chemical moieties in the complex film structure deposited onto the silica surface. 

The reaction of interest—response of the monomolecular complex film to changes of pH—occurred more rapidly than the measurement technique could follow—i.e., in less than ca. 10 seconds. Such rapid response implied that the dissociation equilibrium was mobile and depended principally upon the electrostatic state of the film. 

If it is assumed that the magnitude of the change in complex film surface pressure reflects the extent of protein-detergent interaction, it is possible to identify and characterize the binding groups. 

Studies by Nishiyama and Fujihara [149] utilizing azobenzene derivative (27) as isomerizable chromophores have demonstrated the importance of reaction cavity free volume in L-B films. The L-B films of amphiphilic derivative 4-octyl-4 -(3-carboxytrimethyleneoxy)-azobenzene (27) upon irradiation was found to be stable, no geometric isomerization of the azobennzene moiety occurred. This compound forms L-B films with water soluble polyallylamine 28 at an air-water interface. Reversible cis-trans photoisomerization occurs in the film containing 28. The reversible photoisomerization reaction in polyion complexed films is thought to occur because of the increased area per molecule provided in the film. The cross sections of molecule 27 in the pure film and in film containing 28 were estimated to be 0.28 and 0.39 nm2. Such an increased area per molecule... 

A typical method for fabricating multiple complex layers is illustrated in Figure 2.11,12 First, an Au/mica or Au/ITO plate is immersed in a chloroform solution of tpy-AB-SS-AB-tpy (tpy=2,2 6, 2" -terpyridyl), providing Au-S-AB-tpy SAM on the plate. In the case of connecting the Fe(II) ion, the tpy-terminated plate is immersed in 0.1 M Fe(BF4)2 aq or (NH4)2Fe(S04)2 aq to form a metal complex. Subsequently, the metal-terminated surface is immersed in a chloroform solution of the ligand Lj or L2 to form a bis(tpy)iron structure (Fig. 2b). The latter two processes are repeated for the preparation of multilayered bis(tpy)iron (II) complex films with linear structures. When L3 is used instead of Lj or L2, the resulting molecular wires have a dendritic structure (Fig. 2c). 

A. Bottom-Up Fabrication of the Porphyrin-Terminated Redox-Conducting Metal Complex Film on ITO... 

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