(PHENYLEN-CARBAZOLYEN)S COPOLYMERS - NEW ELECTROACTIVE MATERIALS WITH ADJUSTABLE PROPERTIES

(phenylen-carbazolylen)s copolymers with variable composition and properties were prepared from a dehalogenative polycondensation of 4,4' dihalogenobiphenyl and 3,6 dibromo-N-alkylcarbazole mixture in the presence of zero-valent nickel catalyst. These copolymers are partly soluble in dipolar aprotic solvents, this solubility comes from carbazolylene unit and is depending on the composition of the material; for a given composition, it increases with the length of aliphatic substituent on nitrogen atom. Conductivity upon doping of these materials is variable between that of each homopolymer by checking its composition. Owing to the partial solubility of carbazolylene-rich copolymers in organic solvents, thin films can be coated onto various supports from a solution. On the other hand thin films of copolymers-rich in phenylene unit can be deposited by cathodic reduction of monomers mixture onto solid cathod (ITO glass, glassy carbon...). Electrochemical behaviour of these films in the range 0-1,7 V versus SCE in CH3CN/LiClO4 medium is strongly dependent on the copolymer composition. For a carbazolylene-rich film, electrochemical properties exhibit two redox systems as for poly (N-alkyl-3,6 carbazolylene), while poor carbazolylene films display one additionnal oxidation process; furthermore, in the last case, films are both oxidizable and reducible into acetonitrile with NBu4BF4 as supporting salt. All these data show that these copolymers compose a new class of electroactive materials with adjustable properties.