Solution-processable CEPs

Polyaniline (PAn) is most amenable to solution processing. The emeraldine base (EB) form of PAn is soluble in selected solvents such as methyl pyrrolidinone1 or strong acids.2 3 More recently, it has been discovered that solubility of the doped form can be induced by the use of appropriate surfactant-like molecules as dopants.4 Camphorsulfonic acid (HCSA) and dodecylbenzenesulfonic acid have proved particularly useful in this regard. Once solubilized, these PAn s can be cast into sheets or blended with other conventional polymer structures. For example, the pres- 

When PAn/CSA is dissolved in m-cresol with poly(methyl methacrylate)-(PMMA), this can be spun-cast to form optically transparent films.5 

Pron and coworkers6 have blended PAn with cellulose acetate and cast from m-cresol to produce highly transparent and conductive ( 1 S cm-1) PAn. Addition of plasticizers (in particular, phenylphosphonic acid) not only resulted in more flexible films but lowered the percolation threshold for PAn to an amazing 0.05% (w/w). 

De Paoli and coworkers7 have used the more soluble poly(o-methoxyaniline) doped with p-toluene sulfonic acid to prepare a composite blend with poly(epichlorohydrin-co-ethylene oxide), but conductivities were relatively low (10-3 S cm-1) even with a high 50% (w/w) conducting polymer loading. 

Others8 have blended PAn doped with dodecylbenzenesulfonic acid with poly(vinyl alcohol) (PVA) in water or with polyacrylate in organic solvents to obtain transparent conductive composites. 

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Printing is also an old art that is now seen in a new light for fabrication of advanced products including electronic components. Solution-processable CEPs are inherently suitable for fabrication using printing methods, and their availability is already leading to low-cost sensors and cheap, disposable electronics. 

Integration/fabrication after polymerization Solution processable CEPs Melt-processable CEPs... 

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