Mass-transfer, polymer domain

Another promising area for polymer development, as alluded to by Tirrell [5], is microelectronics. Plasma polymerization can be used to produce a polymeric coating directly on a substrate changing the composition of the gas feed allows a wide variation in the chemical composition of the surface produced [32], The same technique can also be used to modify surfaces for other applications, such as to improve the blood compatibility of biomaterials. The essential processes occurring in a plasma—mass transfer and reaction kinetics—have long been the domain of chemical engineers. 

Interfacial electron-transfer reactions between polymer-bonded metal complexes and the substrates in solution phase were studied to show colloid aspects of polymer catalysis. A polymer-bonded metal complex often shows a specifically catalytic behavior, because the electron-transfer reactivity is strongly affected by the pol)rmer matrix that surrounds the complex. The electron-transfer reaction of the amphiphilic block copol)rmer-bonded Cu(II) complex with Fe(II)(phenanthroline)3 proceeded due to a favorable entropic contribution, which indicated hydrophobic environmental effect of the copolymer. An electrochemical study of the electron-transfer reaction between a poly(xylylviologen) coated electrode and Fe(III) ion gave the diffusion constants of mass-transfer and electron-exchange and the rate constant of electron-transfer in the macromolecular domain. 

The mass-transfer and electron-transfer in the polymer domain is shown as a function of the thickness of the coated pol)rmer film in Figure 6. The currents i and 2 at infinite rotation were calculated by using Routecky-Levich equation (1 ) they represent the mass-transfer and electron-transfer in the pol)rmer domain. The i infinite value decreases with the film thickness, which means that contribution of the mass-transfer process to the redox reaction decreases with the film thickness. 

Polymer Domain Domain Substrate Mass-transfer Electron- transfer... 

These results suggest some factors for the preparation of electrodes with electron-transfer ability, (i) There is an optimum thickness of the coated polymer film for the electron-transfer reaction, (ii) The polymer matrix should be flexible. Otherwise, the matrix retards the diffusion of a counter ion and suppresses the effective collision between redox sites. (iii) A hydrophilic but uncharged polymer domain is suitable for the mass-transfer process in catalysis. A series of polymer complex coated electrodes were prepared as interfacial catalysts (16), one example is given below. 

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