Synthesis and properties of aniline, thiophene and Schiff base copolymer

Electronically conducting polymers have attracted considerable attention in the last two decades, ever since it was discovered that a conjugated polymer can be converted into an electrical conductor by simple doping process. Among all the conducting polymers known, polyaniline is the most unique polymer from both science and technology point of view. Polyaniline can be prepared by either chemical or electrochemical oxidation of aniline. However, one of the disadvantages associated with the conventional synthesis of polyaniline is the occurrence of side reactions like crosslinking and degradation of the polymer. We have devised a new method for the synthesis of polyaniline and its derivatives, in which a small amount of aromatic additives such as p-phenylenediamine, benzidine, p-amino diphenylamine, etc is introduced in the polymerization system. In the presence of these aromatic additives, the rate of polymerization increases drastically and the lower applied potentials or milder oxidants can be employed in the polymerization system. A series of gel permeation chromatography studies was performed on the electrochemically synthesized polyaniline under various conditions. The effect of the additives and their concentration on the molecular weight and molecular weight distribution of the resultant polyaniline was investigated. We have successfully synthesized a series of copolymers of aniline with alkyl, alkoxy, and chloro substituted anilines via chemical and electrochemical polymerization. The compositions of the copolymers were determined by 1H NMR spectroscopy and elemental analysis and can be changed by variation of the monomer feed ratio. The relationship between the copolymer composition and monomer feed ratio was established. And the reactivity ratios of the monomers could be interpreted based on the proposed mechanism. One of the major problems in the applications of polythiophene another important conducting polymer, is the poor mechanical properties of the polymer. A new polymer, poly(2,2'-bithienylmethyl methacrylate) was synthesized and used as a polymeric initiator in the polymerization of 3-alkylthiophenes to afford a new family of comb like polymers. These comb type polymers were found to have improved conductivity in comparison to the polythiophene composites. A new acetylene terminated Schiff base monomer was synthesized and characterized. The polymers prepared exhibited excellent thermal stability.