Electrically conductive materials on poly(thiophene) base and its poly(alkyl) derivatives

Poly(thiophene), polyalkyl derivatives (poly methylthiophene and poly-octylthiphene) based homopolymers and their corresponding copolymers have been synthesized using chemical and electrochemical procedures. The chemically synthesized powders, received by oxidative polymerization in presence of FeCI3 as oxidative agent, have been characterized by FTIR, UVIVIS, TGAIDSC, optical, cyclic voltammetric and HPLC measurements. The influence of the alkyl substituent on the conjugation length (Nc), the degree of polymerization (Ndp) and the presence of defects (Nc=0) has been shown. Soluble systems have been obtained as a result of the main chain conjugation shortening and introduction of long octyl groups in the thiophene ring. The electrochemical deposition of the investigated polymers has been performed on platinum and titanium electrodes. The reduced forms of the polymer films have been characterized by FTIR and optical microscopy. The molecular masses on several soluble systems have been determined. The influence of the electrode material and the alkyl substituent length on the redox properties and the above mentioned characteristic (Nc, Ndp, Nc=0,) was shown. The kinetics of the relaxation process has been analyzed using cyclic voltammetric method by analyzing the first anodic after the polymer film was kept for some time tw at potentials corresponding to their neutral state. It was demonstrated that the alkyl substituent length and the nature of the electrode material have a great influence on the relaxation behavior of the polymer films. Considerable suppression of the relaxation was achieved in copolymers containing substituted thiophene rings with long octyl groups.(Author)