Pyrrole/phenylene copolymers

We have synthesized such a precursor polymer by using the Stetter reaction (scheme 2). Poly-1,4-phenylene-1, 4 -butanedione 9 was formed in the reaction of terephthalic-dicarboxaldehyde 10 and the bis-Mannich base of 1,4-diaeetylbenzene 11 in a yield of 81%. The conversion of 9 into the alternating copolymers of p -phenylene-2,5-pyrrole 12 and p-phenylene-2,5-thiophene 13 is performed with liquid NH3 and Lawesson s reagent, respectively (scheme 3). Upon doping with either Ig or AsFg both polymers 12 and 13 become electrically conducting with specific conductivities up to 0.1 S/cm. 

A copolymer of phenylene oxide and pyrrole has been synthesized by Kumar et al. [214J. Using an acetonitrile solution containing 0.6 M tetrabutylammonium perchlorate, 3 M pyrrole, and 1 M phenol, an 8-/u.m black film was formed. A current density of 10 mA/cm at 4 V was required. The film could be peeled off the electrode. A 2 1 1 ratio of phenylene oxide/pyrrole/perchlorate dopant ions was calculated from chemical analysis data. The room temperature conductivity of the film was 4 S cm". A positive thermopower value (30 fiV/K) is consistent with p-doping and moderate conductivity. 

An interesting alternative is the chemical oxidation of heterocycles (e.g. thiophene or pyrrole) dissolved in an organic solvent (e.g. ethanol) on the surface of various materials. Conductive coatings (thickness 0.01 pm) can be produced on films of poly(phenylene sulfone), block copolymers of butadiene and styrene (Ultrason, Styrolux), poly(vinyl chloride), and other polymer films to give transparent, antistatic films with conductivities of about 0.001 S cm . Ceramics and glass can also be coated in this way. In addition, porous... 

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