SYNTHESIS AND CHARACTERIZATION OF POLY(2-METHOXY-5-NITRO-1,4-PHENYLENEVINYLENE) AND POLY(1,4-PHENYLENEVINYLENE-CO-2-METHOXY-5-NITRO-1,4-PHENYLENEVINYLENE)S

Abstract

The preparation of poly(2-methoxy-5-nitro-1,4-phenylenevinylene) (PMNPV) and a series of poly(1,4-phenylenevinylene-co-2-methoxy-5-nitro-1,4-phenylenevinylene)s (poly(PV-co-MNPV)s) is described. All the polymers could be synthesized via the water-soluble polyelectrolyte precursor route. The precursor copolymers revealed diminished solution viscosity values with increasing content of the MNPV unit. The UV-vis spectra of the copolymers were blue-shifted when compared with that of the parent PPV, which implies an increased band-gap. This can be ascribed to the strong electron-withdrawing nature of the NO2 group, which overwhelms the electron-donating power of the OCH3 group. In spite of such spectroscopic characteristics, the copolymers containing a low level of MNPV units exhibit improved dopability toward I2 and FeCl3. Electrical conductivity of the doped copolymers depends strongly on their composition; it reaches a maximum value at about 5 mol % of MNPV units and then drops rapidly with further increase in the content of the comonomer unit. For this maximum composition, conductivity values are 5.2 x 10(-3) and 2.2 x 10 S cm-1, respectively, for the two dopants. Uniaxially stretched samples, in general, showed much higher conductivities along the drawing direction.