Electroactive materials monolayers

Finally, the SECM is not limited to electroactive materials. Novel approaches based on other modes, currently under investigation, will enable us to modify surfaces with organic monolayers, polymers, and biological molecules. This is the area in which the future of SECM nanofabrication looks most bright. Elowever, the fulfillment of its promise depends on the development of generic techniques that will increase the speed at which it can carry out modification. 

Similar monolayers have been prepared with a diversity of electroactive units with the ultimate goal of elucidating the subtle balance between the structural and the electronic factors that regulate interfacial electron transfer.5,9,10 In particular, these studies have focused their attention on the rationalization of the influence that the distance between the electrode surface and the redox centers as well as the nature of the linkers between them have on the rates of electron transfer. In parallel to these fundamental investigations, the ability of thiols to anchor electroactive units on metallic electrodes has also been exploited to fabricate a wealth of nanostructured materials with tailored functions and properties.6-8 Indeed, these convenient building... 

Chapter 13 was largely concerned with adsorbed species that are not electroactive. In this chapter we consider electroactive monolayers and thicker films on conductive substrates these are frequently called chemically modified electrodes. This area of electrochemistry has been a very active one in recent years, and a number of reviews discussing the preparation, characterization, and electrochemical behavior of chemically modified electrodes are available (1-14). These electrodes are often prepared by the modification of a conductive substrate to produce an electrode suited to a particular function, whose properties are different from those of the unmodified substrate. Modified electrodes can be prepared in several different ways, as discussed in vSection 14.2, including irreversible adsorption, covalent attachment of a monolayer, and coating the electrode with films of polymers or other materials. 

Figure 6.4. The treatment of electrochemical systems with adsorption is significantly more complicated given that we must select a suitable model to describe the adsorption process which will introduce new variables, uncertainties and approximations. Moreover, as will be discussed below, in general the models will lead to non-linear terms in the mathematical problem. For all the above reasons, it is common practice to try to minimise the incidence of adsorption by means of the experimental conditions (mainly the electrode material and solvent). However, in some situations adsorption cannot be avoided (being even intrinsic to the process under study) or it can be desirable as in the modification of electrodes with electroactive monolayers for electroanalysis or electrocatalysis.

By its very nature, copolymerization offers the unique capability or opportunity for chemists to design and construct molecules with special electronic properties using established techniques. The Langmuir-Blodgett (LB) technique, for instance, enables the chemist to organize molecules into highly ordered monolayers and to manipulate a multilayer film to a desired architecture. Copolymerization enables the molecular architect or tailor to incorporate various molecules, e.g. biological components, into electroactive PP and PT polymers. The number of potential applications for these unique materials is unlimited. 

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