Synthesis and Characterization of Regioregular Cyano-Substituted Poly(p-phenylenevinylene)

A regioregular cyno-substituted poly(p-phenylenevinylene) [CN-(PPV)] with asymmetric substitutions with methoxy and long alkoxy groups was synthesized using a novel monomer. Soluble CN-PPV (1) was synthesized through alternative polycondensation of a dialdehyde and a dinitrile. Treatment of monomer with t-BuOK in refluxing toluene/t-BuOH mixture (10:1) afforded black solid 3, which was further studied. FT-IR spectra demonstrated that the peak of the cyano groups was shifted after polymerization. The regioregularity of CN-PPVs was characterized using 1H NMR spectra. Optical properties of the CN-PPVs in solutions and film states were also investigated. Thin films were spin-coated from hot chlorobenzene solutions. The regioregular CN-PPV showed stronger interchain interactions in the films and higher electron mobility than the regiorandom counterpart. The onset potentials of the oxidation peaks in CV indicate that the regioregular CN-PPV has a lower oxidation potential by 0.12 V than the regiorandom.