Wang Fosong

Polymerization of substituted aniline and characterization of the polymers obtained

Abstract Chemical polymerization of m -toluidine, o -chloroaniline and nitroaniline has been studied, and characterization of the resulting polymers performed by DSC, X-ray, i.r., XPS and conductivity measurements. It is found that the substituted group of aniline affects not only the polymerization reaction, but also the properties of the polymers obtained. The polymerization conditions, such as the pH value of the polymerization solution, have a certain influence on the polymer yield and its conductivity. The solubility of polymers of substituted aniline (SPA n ) is similar to that of polyaniline. The results on X-ray diffraction of SPA n reveal that the substituted group has some effect on the regularity of the polymers. DSC measurements show the existence of an endothermic peak as a disordering of the regular segments. The spin concentration of SPA n increases with increasing conductivity of the polymers to a certain degree. On the basis of the XPS and doping reaction of SPA n , a possible structure of the conducting polymer is proposed.

Study on the Crystallinity of Polyaniline

Abstract WAXD, SEM, DSC and TGA were used to investigate the crystallinity of polyaniline (PAn). The results show that the crystallization behaviors of undoped PAn depend on its polymerization conditions. The crystallinity of undoped PAn decreases with the increasing acidity from 0.001 to 7N in polymerization solution. Doped PAn crystallizes more easily than undoped one and the crystallinity increases with increasing doping level. Appropriate heat treatment can enhance the crystallization ability of PAn.

On the metallic temperature dependence of the conductivity of doped polyacetylene

Abstract The true metallic temperature dependence of the conductivity of various doped polyacetylene films of both fibrillar and granular morphology has been experimentaly demonstrated by voltage shorted compaction measurements.

STUDY ON POLYANILINE FILM WITH HIGH DENSITY AND HIGH MECHANICAL STRENGTH

Free-standing film of polyaniline with excellent mechanical and electrical properties has been successfully prepared by using the solution-casting method. The results show that its tensile strength, Youngs modulus and elongation at break are about 87.9 MPa, 1563.9 MPa and 10.2%, respectively. It is essential that the soluble polyaniline should be appropriately treated in some suitable organic solvents before making a free-standing film. Films having lustrous, smooth surface, high density and good flexibility can only be doped by protonic acids of small molecular sizes, such as HCl, HClO4 and H2SO4, to the metallic conducting regime (σ=6.7 S/cm). Discussions have been made in terms of doping behavior essentially affecting drawability and mechanical strengths.