ELECTROCHEMICAL AND XPS INVESTIGATIONS OF THE ANODIC SUBSTITUTION OF AN ELECTRONIC CONDUCTING POLYMER - CYANATION OF OLY[(1,4-DIMETHOXYBENZENE)-CO-(3-METHYLTHIOPHENE)]

The oxidation of BF4--doped oly[(1,4-dimethoxybenzene)-co-(3-methylthi ophene)] (PDMB-PMeTh) at 1.2 +/- 0.1 V (vs. 10(-1) M Ag+\Ag) in dry CH 3CN + 0.2 M NEt4CN leads to a new CN-substituted copolymer. Comparativ e to the PDMB homopolymer, this electrochemical reaction is more effic iently performed, owing to better film properties provided by PMeTh. T he electrochemical and XPS data show that the anodic cyanation is achi eved specifically on PDMB and results mainly in the aromatic substitut ion of hydrogen on the DMB unit rather than the replacement of aromati c methoxyl by nitrile. Thus the cyanation mechanism would be different from that demonstrated in solution with DMB, for which p-methoxybenzo nitrile was generated. The ratio of the MeTh and DMB units in the copo lymer is estimated at 0.4 +/- 0.05 and the cyanation results in the li nkage of 1.4 +/-: 0.2 C = N group per DMB unit. Moreover, this study r eveals that cations and anions from the electrolyte are strongly retai ned in the copolymer and partially exchanged after the electrosynthesi s, cyanation and chemical treatment steps. (C) 1997 Elsevier Science S .A.