STRUCTURES AND PROPERTIES OF THE SOLUBLE POLYANILINES, N-ALKYLATED EMERALDINE BASES

The N-alkylated emeraldine bases (N-butyl, N-hexyl, N-octyl, N-decyl, N-dodecyl, and N-hexadecyl) are synthesized by incorporation of flexib le alkyl chains onto the polyaniline (PAn) through an N-alkylation met hod with the emeraldine base. The solubility of PAn in common organic solvents is improved remarkably with the alkylation and the oxidation level is maintained at 40-50 mol% (close to that of the original emera ldine base, 50%) allowing for an adequate acid doping. When carbon num ber of the alkyl side chain is six or more, the polymers can be dissol ved in common organic solvents (such as tetrahydrofuran, dichlorometha ne, and chloroform) even in the presence of a protonic organic acid as dopant, such as dodecylbenzene sulfonic acid (DDBSA) and camphor sulf onic acid (CSA), and free-standing films can be obtained by casting fr om the solutions. When the carbon number is 12, the polymer film is fl exible. DDBSA-doped N-alkylated emeraldine salt films cast from polyme r solutions in dichloromethane in the presence of the acid dopant have maximum conductivities in the range 10(-2) - 10(-4) S/cm, being two t o three orders of magnitude higher than those of the reported HClO4-do ped poly(N-alkylaniline)s. (C) 1998 Elsevier Science S.A.