Polypyrrole-vinyl aniline modified cyclohexanone formaldehyde resin copolymers: A comparative study of the resin preparation

In this study, the synthesis of polypyrrole-b-vinyl aniline modified cyclohexanone formaldehyde resin (PPy-b-CFVAnR) block copolymers by a combination of condensation polymerization and chemical oxidative polymerization processes was examined. First, a cyclohexanone formaldehyde resin containing vinyl aniline units [4- vinyl aniline modified cyclşohexanone formaldehyde resin (CFVAnR)] was prepared by a direct condensation reaction of 4-vinyl aniline and cyclohexanone with formaldehyde in an in situ modification reaction. CFVAnR and pyrrole (Py) were then used with a conventional method of in situ chemical oxidative polymerization. The reactions were carried out with heat-activated potassium persulfate salt in the presence of p-toluene sulfonic acid in a dimethyl sulfoxide-water binary solvent system; this led to the formation of desired block copolymers. The effects of the oxidant-monomer molar ratio, dopant existence, addition order of the reactants, and reaction temperature on the yield, conductivity, and morphology of the resulting products were investigated. PPy-b-CFVAnR copolymers prepared with a resin-to-Py molar ratio of 1:40 showed conductivity in the range 3.7 × 10^-1 to 3.8 × 10^-2 S/cm. Oxidant-to-Py molar ratios of 0.5 and 1.0 were proposed to be the optimum stoichiometries for higher conductivity and yield, respectively, of the copolymer. The morphology of the copolymer (PPy-b-CFVAnR) was investigated with environmental scanning electron microscopy analyses. The results indicate that the surface of the copolymer was composed of well-distributed nanospheres with average particle diameters of 60-85 nm. Also, the synthesized PPy-b-CFVAnR had a higher thermal stability than the pure CFVAnR. The chemical composition and structure of the PPy-b-CFVAnR copolymers were characterized by Fourier transform infrared spectroscopy and measurement.