Studies On Solid-state Synthesis Of Nitrogen-and Sulfur-containing Conducting Polymers

In this paper, polyaniline (PNAI), poly(o-methoxyaniline) (POMA) and poly(o-toluidine) (POT) were prepared by a novel solid-state polymerization method with the dicarboxylic acid (oxalic acid, maleic acid, succinic acid) as doping agents, respectively. And we attempt to study the effect ofβ-cyclodextrin (β-CD) on the solid-state polymerization reaction of PANI salts doped with HCl, using ammonium peroxydisulfate (APS) as oxidant. Polyindole (PIN), polytrithiophene (PTT) were also synthesized by solid-state polymerization method. Relative conducting polymers were characterized by FTIR spectroscopy, UV-vis spectroscopy, X-ray diffraction, scanning electron microscope (SEM) and transmission electron microscopy (TEM). The electrical conductivity of the polymers was also measured. The main results are summarized as follows:1. PANI, POMA and POT doped by oxalic acid with small molecular size displayed higher doping level. However, the polymers doped by maleic acid withπelectron in the structure had the highest electrical conductivity. POMA and POT doped by acids with big molecular size could be soluble in some ordinary organic solvents.2. In the presence ofβ-CD, PANI salts doped with HCl were prepared. The role ofβ-CD would vary from an encapsule to a bulky dopant with the increase of content ofβ-CD. When the molar ratio of aniline toβ-CD was 80/20, the obtained PANI salt displayed higher crystallinity, conductivity and electrochemical properties. However, these properties were opposite on condition that the molar ratio of aniline toβ-CD was 50/50.3. The PANI/MnOx composite was prepared by one step solid-state polymerization. And we attempt to study the reductive mechanism of KMnO4. By controlling reactive temperature, time, the molar ratio of oxidant/monomer, we can obtained different composite.4. PIN was synthesized using APS as an oxidant by solid-state polymerization at room temperature. It was observed that yield and conductivity of polymer were highest when the molar ratio of APS/indole was 2, and that polymerization mainly happened at the 2, 3-position of indole molecule. And obtained PIN displayed better crystallinity and good electrochemical properties.5. PTT nanoparticles were successfully synthesized by solid-state polymerization using APS, hexahydrated ferric chloride (FeCl3·H2O) and the mixture (MIX) of APS and FeCl3·H2O as oxidants, respectively. TEM showed that the diameter of particles is about 30-50 nm. The results showed that PTT synthesized using Mix as oxidant displayed higher degree of polymerization, longer conjugated length and higher conductivity than that of PTT synthesized by using APS or FeCl3·H2O as oxidants.