Electrochemical copolymerization of aniline and aniline-2,5-disulfonic acid (ADSA) was carried out in HCI solutions. The presence of ADSA inhibited significantly the growth of polyaniline (PAn), although the voltammetry of the copolymer was still similar to that of conventional PAn. As the ADSA concentration increased, the deposition rate of the copolymer decreased rapidly and finally no solid film was deposited on the electrode surface. When the ADSA concentration was lower than-5 mM, the depression effect of ADSA on the growth rate of the copolymer is mainly due to its stronger adsorption at the electrode surface. For higher ADSA concentrations, the inhibiting effect of ADSA was dominated by its termination effects, which led to more soluble oligomers and in turn resulted in lower deposition efficiency. Electrolysis of ADSA solution might result in a water-soluble fully sulfonated PAn. aniline, aniline-2,S-disulfonic acid, copolymerization, polyaniline, water-soluble

Electropolymerization of aniline-2,5-disulfonic acid in aqueous solutions results in formation of a water-soluble self-doped polymer. E€ects of synthesis conditions were investigated on conductivity and molecular-weight distribution of the polymer. The polymer shows solubility in water high up to 109 mg cm-3. The conductivity of the polymer, with best value of about 0.34 S cm-1, is independent on pH up to at least pH 9.

Electroluminescence (EL) characteristics of the double-MPc-layered devices consisting of ITO/MPc1/MPc2/Alq3/Mg-Ag were investigated, where MPc1 and MPc2 represent two metallophthalocyanines and Alq3 stands for tris(8-quinolinolato)aluminum(III). A compatible double-MPc-layered structure led to a decreased hole-injection barrier at the ITO/MPc1 interface and an increased electronblocking ability of the MPc2 layer in the device. The EL efficiency of the device was improved further by using a 4,40-bis(m-tolyphenylamino) biphenyl (TPD) layer as an additional hole-transport layer due to its good electron-blocking ability. For the double-MPc-layered devices with a TPD layer, the EL performances were dependent primarily on the electronic structure of ITO/MPc1 interface rather than that of MPc1/ MPc2 or MPc2/TPD interface.

In aqueous acidic solutions, a higher peak current and a more positive peak potential for the first oxidation peak of polyaniline (PAN) compared with those obtained in a multicycle voltammogram was observed after holding at a sufficiently negative potential. This is referred to as a memory effect in PAN. An exception to this behavior was observed at low scan rate, when the peak potential in the first voltammogram can be less positive than that in the multicycle voltammogram. When the solvent was substituted by a mixture of water and some organic solvents, the first oxidation peak obtained in aqueous solution split into two subpeaks. The first subpeak, with a less positive peak potential, contributed strongly to the memory effect observed in PAN, but the second subpeak, with a more positive peak potential, was little influenced by holding in the reduced state. The exception mentioned above could be explained in terms of the existence of these two subpeaks if it could be shown that they were present for PAN in any solvent. These two subpeaks may reflect different structures in reduced PAN or be due to solvent effects on PAN intermediates during cycling.

Influences of an inserted hole-blocking bathocuproine (BC) layer were investigated on electroluminescence (EL) performances of organic light emitting devices with a configuration of ITO/BC/Alq3/Mg–Ag, where Alq3 is tris(8-quinolinolato)aluminum(III). Variations in the thickness of organic layers and bias voltages were found to alternate the emissive region from the BC layer to the Alq3 layer, resulting in shift of the emission wavelength in the EL spectra of the devices.