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Copolymers of poly(ethyl cyanoacrylate- co -methyl methacrylate) (PECA- co -PMMA) with various compositions were synthesized by free radical bulk polymerization in an effort to control degradation and stability as well as glass transition temperature to overcome intrinsic poor processability of the poly(ethyl cyanoacrylate) (PECA) homopolymer. The copolymers were found to have an alternating random tendency, which was responsible for the efficient inhibition of the unzipping degradation from the polymer chain. Consequently, the stability of the copolymers at elevated temperature and in solution was significantly improved compared to the PECA homopolymer. The glass transition temperatures of the copolymers were lowered by the incorporation of the methyl methacrylate (MMA), thereby further widening the operating temperature range of the polymer. On the other hand, the copolymer films exhibited hydrolytic degradation in phosphate buffered saline (PBS) solution at 37 °C, which is promising for their use as novel biomaterials.

Poly(ethyl cyanoacrylate) was synthesized using N , N ′-dimethyl- p -toluidine as an initiator through an anionic/zwitterionic pathway. The degradability and the degradation mechanism of the prepared polymer were examined from various viewpoints. A combination of TGA and GPC analysis allowed us to confirm that the thermal degradation of this polymer was predominantly due to an unzipping depolymerization process initiated from the polymer chain terminus. The polymer was inherently unstable and exhibited interesting degradation behavior in solution with basic reagents. The degradation in solution was also found to be attributed to the unzipping of the monomer from the chain end. However, the degradation behavior of the polymer could be controlled by changing solvents, temperatures, and additives. These findings give an insight into the degradation behavior of poly(alkyl cyanoacrylate)s, which is a crucial point in utilizing these polymer homologues for various applications.

Poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles with enhanced conductivity and processability were prepared by oxidative polymerization in dodecylbenzne sulfonic acid (DBSA) micellar solutions. DBSA was used to act simultaneously as a surfactant to form micelles and as a doping agent. Monomers of EDOT, which has extremely low solubility to water, were easily solubilized in aqueous DBSA micellar solution. The effects of DBSA on the resulting PEDOT structure, morphology and electrical property were investigated when DBSA was used in combination with two different oxidants, i.e., iron(III) chloride and ammonium persulfate. The electrical conductivity was varied with the polymerization conditions, and it was relatively high up to 50 S/cm. The morphology of the particles, determined by Field emission scanning electron microscopy (FE-SEM), appeared to be quite spherical and their sizes ranged from 35 to 100 nm in diameter. The colloidal properties of the PEDOT nanoparticles were also investigated.

The effect of methanol cosolvent on the synthesis of polypyrrole-silica colloidal nanocomposites using ultrafine silica sols in combination with both FeCl3 and APS oxidants has been investigated. Two protocols were evaluated: the addition of methanol to an aqueous silica sol and the addition of water to a methanolic silica sol. The latter protocol proved to be more robust, since it allowed colloidally stable dispersions to be prepared at higher methanol content (up to 50 vol% using the APS oxidant). This allowed greater control over the particle size of the nanocomposite particles. In general, the spectroscopic data, the particle size range, silica contents and electrical conductivities of these nanocomposites were similar to those reported earlier for purely aqueous formulations. Polypyrrole contents ranged from 49 to 71% by mass and particle diameters varied from around 160 to 360 nm. In terms of colloid stability, the APS oxidant was preferred for nanocomposite syntheses in the presence of methanol. However, the FeCl3 oxidant generally gave higher conductivities and narrower size distributions under comparable conditions. HF etching experiments combined with transmission electron microscopy studies indicated that, to a first approximation, these nanocomposite particles had core-shell morphologies, with a hydrophobic polypyrrole core and a hydrophilic silica shell that compose approximately one monolayer of silica sol particles. Finally, aqueous electrophoresis measurements suggested that the polypyrrole-silica nanocomposites were silica-rich and that the methanolic silica sol was more hydrophobic (lower surface charge density) than the aqueous silica sol.

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.

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.

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.