SOLUTIONS IN UNUSUAL OR DIFFICULT SOLVENTS

Some success has been achieved in preparation of solutions of CPs in the doped form in unusual or very-difficult-to-handle solvents. AsFj, cone. H2SO4 and m-cresol are some of these solvents. In an early study, Frommer [243] showed that doped (with AsFj) poly(p-phenylene sulfide) could be dissolved efficiently in ASF3. Unfortunately, however, a film cast after solvent removal would not redissolve, i.e. the solution was not reversible. 

The more common P(ANi) can be dissolved in concentrated (typically 97%) acids such as H2SO4, CH3SO3H and CF3SO3H (methane and trifluoromethane sulfonic acids). Interestingly, P(ANi) concentrations in these solvents from a few % to 20% 

In an adaptation of these concentrated acid methods, Pron et al. [246] used dialkyl esters of phosphoric acid to protonate P(ANi), either in solution (solvents such as toluene, THF, m-cresol), or by mechanical mixing with neat diester. The resulting protonated P(ANi) was soluble in the protonated form in solvents such as decaline (up to 12 w/w%). Such solutions could then be used for solubilizing poly(methyl methacrylate), poly(acrylonitrile butadiene-styrene) (ABS) or other thermoplastics, and films or fibers could be cast or spun therefrom. Curiously again, however, practical applications of these promising conductive thermoplastic blends have so far not been seen. 

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