Assembly of Conducting Polymers in Host Matrices

Conducting polymers can be integrated into other structures at the point of assembly using either the chemical or the electrochemical oxidative route. 

The simplest approach is to have a suitable host structure imbibe the oxidant or monomer. This material is then exposed to the monomer or oxidant, respectively, and the polymer material is grown throughout. For example, Bjorklund and Lund-strom27 described a procedure in which cellulose paper was first exposed to a metal salt (FeCl3) that would act as the polymerization agent. The metal salt-soaked paper was then exposed to the pyrrole monomer in liquid or vapor form. Materials with conductivities of approximately 2 S cm-1 could be produced using this approach. 

We have found similar results in our laboratories making impregnated papers with PPy and PAn for inverse thin-layer chromatography.28 The method we used to prepare PAn-modified paper was to load filter paper strips with aniline, which was allowed to diffuse throughout the paper for about 10 min. The strips were then immersed in FeCl3 that had been acidified with HC1. The PAn adheres well to the filter paper when it is dried, and no problems with chemical instability were observed. The morphology of the polymer surface was that of the filter paper substrate. 

It was noted by MacDiarmid and Epstein as early as 1989 that PAn salts may also be deposited as films on a variety of substrates by immersing the substrate in the polymerization mixture.29 In fact, during standard chemical polymerization, one often observes the deposition of a thin, extremely adherent green emeraldine salt (ES) film on the walls of glass reaction vessels, as well as the bulk precipitation of PAn/HA powder. By judicious manipulation of the polymerization conditions such as reagent concentrations/ratios and modification of the substrate surface, one can maximize the surface deposition as opposed to polymer precipitation.30 This phenomenon has been developed into a widely useful in situ polymerization technique for the preparation of PAn films on a variety of insulating surfaces such as glass and plastics, as well as on fibers and fabrics. 

In situ polymerization of aniline is generally carried out in aqueous (NH4)2S208/HC1. The glass support is typically removed from the reaction mixture during the polymerization at the stage when a blue/violet film of pernigraniline salt has formed on its surface. This film is then reduced to the green ES product by reaction with a separate 

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Assembly of conducting polymers in host matrices Chemical polymerization Interfacial polymerization Electrochemical integration Device fabrication... 

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