Method of preparing polyaniline films and highly self-oriented films obtained

A method for preparing a film of on polyanilines a solid support comprising:

• (1) oxidative polymerization in an aqueous acid polymerization medium comprising a) an aniline monomer of formula (An) Rm Ro —C6 H3 —NHR′, in which Rm, Ro and R′, independently of each other, represent H or a linear or branched alkyl, alkoxy, alkylcarboxy or alkylsufonic group containing 1 to 6 carbon atoms, b) an acid, c) an oxidizing agent and d) a salt of formula MXx in which M represents Li, Ca, Na, or K and X represents Cl and x represents 1 or 2 depending on the valency of M, wherein the acid is formic acid and the polymerization takes place in the presence of formic acid and said Cl salt to obtain polyanilines;
• and
• (2a) depositing said polyanilines on said solid support immersed in the polymerization medium to form a film adhering to said support;
• or
• (2b) separating said polyanilines, washing the separated polyanilines with an aqueous solution of an acid which is formic acid, sulphuric acid, sulphonic acid, phosphoric acid, acetic acid or a mixture of any two or more of the foregoing and depositing the washed polyanilines on said support to form a free-standing film;
• wherein the polyanilines of the formed film are at least 80% crystalline and strongly oriented without dissolving said polyanilines in an organic solvent, to obtain a solution, casting of the resulting solution on the support and stretching the resulting film.