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Polyaniline coated poly(butyl methacrylate) core–shell particles were synthesized and formulated into electrically conductive colloidal inks appropriate for use in roll-to-roll printing. Since the first demonstration of an organic field-effect transistor, a specific interest in fabricating low-cost, large area organic electronics through the exploitation of conventional ink-jet, screen, or roll-to-roll printing technologies has developed. Using a commercial roll-to-roll printing press, interdigitated test figures were printed with the core–shell colloidal ink down to a line thickness of ca. 40 µm. The printed zones exhibited a conductivity of ca. 0.5 Ω−1 cm−1, though this conductivity could be modified by altering the composition of the ink to include more uncoated poly(butyl methacrylate) particles. Heating the printed zone above 35 °C allowed the core to flow, resulting in enhanced mechanical properties of the printed zone.

Chemical oxidative polymerization of aniline was performed in a micellar solution of dodecylbenzene sulfonic acid (DBSA, anionic surfactant) to obtain conductive nanoparticles with enhanced thermal stability and processability. DBSA was used to play both the roles of surfactant and dopant. The polymerization kinetics and optimum polymerization conditions were determined by UV–VIS spectra. The optimum molar ratio of oxidant to aniline was 0.5 and DBSA content was the most important factor in the formation of polyaniline (PANI) salt. The polymerization rate was increased with increasing DBSA concentration. The reaction model was proposed on the basis of the roles of DBSA. The electrical conductivity varied with the molar ratio of DBSA to aniline and the highest conductivity of particles was 24 S/cm. The layered structure due to PANI backbone separated by long alkyl chains of DBSA was observed and it seems to facilitate the electrical conduction. The doping level of particle was fairly high and was dependent on the preparative conditions. The average size of the PANI particles determined by Guinier plot of small-angle X-ray scattering (SAXS) measurement was 20–30 nm, which was well coincidence with scanning electron microscopy (SEM) results

Poly(styrene- co -styrene sulfonate) (PS-PSS) latexes have been coated with thin overlayer of polyaniline (PANI) to produce electrically conductive ‘core-shell’ particles (PANI/PS-PSS) in the size of range 30–50 nm in diameter. PS-PSS core particles were prepared by radical emulsion copolymerization and PANI was oxidatively polymerized using ammonium peroxydisulfate (APS) on the surface of PS-PSS latex. PANI thin overlayer was observed in transmission electron microscopy (TEM) images indicating polymerization of aniline takes place preferably on the PS-PSS surface rather than in the aqueous bulk phase. Elemental analysis revealed that the weight percent of styrene sulfonate in PS-PSS copolymer was ca. 5.4% and the conductivities of PANI/PS-PSS pellets were greatly increased with the increase of nitrogen content. Thermal gravimetric analysis (TGA) thermograms showed two main degradation stages beginning at 360 and 460°C that correspond to the decomposition of PS-PSS and PANI, respectively.

Conductivity stability at thermal environment of conductive polyaniline-complexes/polyimide (PANI-complexes/PI) blends, which were doped by camphorsulfonic acid (CSA) and dodecylbenzenesulfonic acid (DBSA), respectively, were investigated by conductivity measurements, electron spin resonance (ESR) spectra, differential and scanning thermometer (DSC). In the conversion process of PANI/Polyamic acid (PAA) to PANI/PI, the blend endeavored some kinds of alteration such as decomplexation of moisture and solvent, dissociation of dopant, crosslinking of PANI chain, and the imidization of PAA chain. PANI-DBSA/PI showed higher thermal stability of conductivity than PANI-CSA/PI, and both samples showed nearly linear decay of conductivity with increasing temperature showing greatly enhancement of conductivity stability. When they were exposed at near or over glass transition temperature, the conductivity decay became faster. The conductivity stability at base environment was also higher for PANI-DBSA/PI due to difficulty in accessing of hydroxyl ion to PANI, which were resulted from dopant. DBSA-doped blends showed increased polaron mobility and concentration at relatively high temperature, which led to extremely higher conductivity and its stability at high temperature. Copyright © 2002 John Wiley & Sons, Ltd.

The effect of solvent and dopant on the thermal transition of polyaniline (PANI) has been investigated principally by dynamic mechanical analysis (DMA). Solvent (NMP) containing film was found to exhibit three thermal transitions in tan δ curve (142, 198, and 272°C). The two lower transitions were disappeared when NMP was removed. Hence, the third peak was suggested to be real glass transition of PANI. The shape of DMA spectra was varied with thermal curing temperature, which is directly related to NMP content. Two other peaks seemed to be due to the evaporation of solvent existing as different environment (free NMP and hydrogen-bonded NMP), which was traced by TGA, FT-IR, and DMA with altering the curing temperature. It was suggested that the third peak was composed of cross-linking reaction between adjacent chains as well as glass transition of polyaniline backbone. NMP free films were prepared by two methods (repeating doping–dedoping cycle and thermal curing). In these films, only one tan δ was observed at over 250°C. When the NMP free film was doped, the DMA peak observed over 250°C was broadened and shifted toward lower temperature.

Small-angle X-ray scattering patterns of polyaniline (PANI) complexes/polyimide (PI) blends were observed in order to analyze the compatibility between two components of the blends. From the experimental results, it was concluded that the microphase separation or molecular level mixing, which was the reflection of compatibility, was dependent on the kinds of dopant (camphorsulfonic acid (CSA) and dodecylbenzene sulfonic acid (DBSA)), PANI content and the imidization state. On account of self-assembling nature of PANI–DBSA, PANI–DBSA/poly(amic acid) (PAA) shows phase-separated morphology. On the other hand, PANI–CSA/PAA blends exhibited well-mixed and high compatible morphology. Thermal curing of these blends brought about the change of blend morphology, which was in correlation with altered chain structure from PAA into PI, and was also a function of PANI content. It was supposed that conversion from PAA to PI by thermal curing processes led to enhancement of compatibility probably due to higher interaction between two components.

Polyaniline (PANI) dispersions consisting of 10–20 nm sized nanoparticles were prepared by oxidation with ammonium peroxydisulfate (APS) in sodium dodecylsulfate (SDS) micellar solutions. Coalescence and coagulation were prevented by electrostatic repulsive interaction between anionic SDS micelles. Particle morphology was dependent on the initial shape of surfactant aggregates (micelles) and the molar ratio of SDS to aniline monomer. Spherical particles were obtained at very low monomer concentration and the shape of particles began to be distorted from the spherical shape as monomer concentration increased at constant 0.2 M SDS concentration. The size of spherical particles was the same order of the micellar size or slightly larger. UV–VIS spectroscopy, compositions of PANI powder, morphology, crystalline structure, thermal stability, molecular weight and conductivity of PANI particles synthesized at various monomer and surfactant concentrations were investigated.

Dielectric responses of polyaniline (PANI) salt films, made from two different methods, were compared to investigate the effect of a dopant and film-formation methods on the dielectric properties. One of the film-formation methods for emeraldine salt was the film-doping method, and the other, the solution-doping method. The conductivity relaxation and dielectric properties were measured by a microdielectrometer at 293 K in the frequency range of 1–100,000 Hz. Dielectric spectra were a function of the dopant in the case of the film-doping method, whereas it was a function of solvent–dopant combinations as well as the dopants in the solution-doping method. The dielectric responses of film-doped samples had similar patterns irrespective of the dopants, while those of solution-doped samples were varied, probably due to different conjugation conditions or/and the conduction mechanism. In the case of film-doped samples, dielectric loss and permittivity values were increased with decreasing dopant sizes. The dielectric relaxation times were also varied depending on the kind of dopants. The different solvent–dopant combinations led to variation of the dielectric responses in the solution-doped PANI due to an altered chain structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2760–2769, 2001

Chemical oxidative polymerization of aniline was studied in a conventional aqueous solution and in micellar solutions of sodium dodecyl sulfate (SDS, anionic surfactant) and nonylphenol ethoxylate(9) (NP-9, nonionic surfactant) to investigate the effect of molecular structure of surfactants on the polymerization kinetics and particle size. The polymerization kinetics in NP-9 micellar solution were very slow, and this result was explained based on the structural characteristics of surfactant. SDS micellar solutions resulted in a highly transparent solution without any precipitates, whereas some precipitates were visually observed in the NP-9 micellar solution after the reaction finished. The electrical conductivities of polyaniline pellets formed with particles prepared in SDS and NP-9 micellar solutions and aqueous solution showed about 20, 4, and 4 S/cm, respectively. The highest electrical conductivity of particles from SDS micellar solution might be due to the smallest size of particles and the highest...

The changes in protonation level ([N+]/[N] ratio), doping state, and conjugation condition for polyaniline-complexes/polyamic acid (PANI-complexes/PAA) blends and their thermally cured polyaniline-complexes/polyimide (PANI-complexes/PI) have been assessed by X-ray photoelectron spectroscopy and UV–Vis spectroscopy. It was suggested that the protonation levels were predominantly associated with dopants that show different protonation ability. By XPS N1s peak convolution, it was found that thermal treatment of blends led to dedoping when the curing temperature reached 250°C. However, stability of protonation state of blends against thermal curing was higher than pure PANI-complexes. Dopants in the blends also affect the distribution of N+ species and thermal stability to curing. Mild thermal treatment (180°C) led to the increase of conjugation length ascribing to the increased order of polymer chain, although their protonation levels were not increased.

A method had been developed to cast organic/inorganic hybrid composites by sol–gel process. This procedure was mainly controlled by the pH of mixing circumstances of organic/inorganic multicomponent solutions and was attributed to the solvent pH. Cast composite from m-cresol solution could not form a uniform hybrid composite film due to the indistinguishable growth and aggregation of silica at pH 7. But bulk conductivity from m-cresol solution was higher than that from NMP solution, which resulted from the secondary-doping effect of the solvent. These conformational changes of the polymer chain and ability to form hybrid composite film were analyzed by means of Fourier-transform infrared (FTIR), wide-angle X-ray diffraction (WAXD), microdielectrometer, thermogravimetric analysis (TGA), and conductivity measurements.

Conducting films of dodecylbenzenesulfonic (DBSA)-doped polyaniline/polyimide (PANI/PI) blends with various compositions were prepared by solvent casting followed by a thermal imidization process. Electrical and physical properties of the blends were characterized by infrared spectroscopy, an X-ray diffraction technique, thermal analysis, a UV-vis spectrophotometer, a dielectrometer, and conductivity measurements. The blends exhibited a relatively low percolation threshold of electrical conductivity at 5 wt % PANI content and showed higher conductivity than that of pure DBSA-doped PANI when the PANI content exceeded 20 wt %. A lower percolation threshold and a lower compatibility was shown between the two components in the blends than those of PANI–camphorsulfonic acid/polyamic acid (PANI–CSA/PAA). A well-defined layered structure due to the alignment of the long alkyl chain dopant perpendicular to the PANI main chain was evidenced by WAXD spectra. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2169–2178, 1999

By using camphorsulfonic acid (CSA) to protonate polyaniline (PANI), the counterion enabled the PANI–CSA complex processable as a solution phase. So camphorsulfonic acid (CSA)-doped polyaniline/polyimide (PANI/PI) blend films were prepared by the solvent casting method using N-methylpyrrolidinone (NMP) as a cosolvent followed by thermal imidization. The conductivity of the PANI–CSA/PAA (50 wt % PANI content) is greater than that of the pure PANI sample at room temperature. As the thermal imidization proceeded, molecular order of polymer chain structure was improved in the resulting PANI–CSA/PI film due to the annealing effect of PANI chain, and this PANI–CSA/PI film showed higher conductivity than PANI–CSA and PANI–CSA/PAA film. PANI–CSA/PI blend films had a good thermal stability of conductivity at high temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1863–1870, 1998

Polyanline (PANI)–silica and poly(3,4-ethylenedioxythiophene) (PEDOT)–silica colloidal composite particles having a diameter of 200–300 nm were synthesized, then converted to intrinsically conducting polymer (ICP)-inks viasolvent exchange. These inks could be inkjet-printed on indium tin oxide-coated poly(ethylene terephthalate) films (ITO-PET film) using a commercial desktop inkjet printer. These PANI–silica or PEDOT–silica/ITO-PET assemblies were utilized as the active layer in electrochromic devices (ECDs). A number of devices were fabricated that exhibited 500 µm size patterning and utilized spatially controlled printing of the particles to allow for a dual image display. In addition, the PANI and PEDOT-based particles were blended into a single ICP ink that allowed for a wider absorption tuning range of the final ECD.