Poly(ester)s and poly(amide)s with fluorene and diphenyl-silane units in the main chain: Effects of iodine doping on the structure and electrical conductivity

摘要

Intramolecular charge transfer interaction between the electron donor and electro acceptor units within the polymeric structure and its optoelectronic properties were studied. The monomer, 9H-fluorene-2,7-dicarboxylic acid, was prepared from 9H-fluorene-2,7-dicarbonitrile using CuCN/N,N-dimethylformamide followed by the decomposition of the complex with FeCl _3x6H _2O in HCl and KOH/H _2O. The formation of two new classes of polymers was reported at different reaction times. The poly(ester) (PEF) was synthesized by the reaction of the diacid monomer with bis(4-hydroxiphenyl) diphenylsilane using tosyl chloride/pyridine/dimethylformamide system as condensing agent. Alternatively, the poly(amide) (PAF) was synthesized by the direct polycondensation of the diacid monomer and bis(4-aminophenyl) diphenylsilane in N-methyl-2-pyrrolidine solution containing dissolved calcium chloride. The resulting new polymers were obtained in good yields and were characterized by FTIR, NMR (~1H, ~(13)C, and ~(29)Si), ESI, Raman, UV (optical gap) and fluorescence spectroscopy. The thermal properties were characterized by DSC and TGA. The electrical conductivity of the polymers was measured before and after exposure to iodine vapor, utilizing films of different thickness. Ellipsometric studies were used for the determination of the film thickness. Morphological differentiation was carried out by SEM-EDX analysis. Oxidation of the polymer films of low thickness decreased their conductivities, mainly due to the small structural changes. For a polymeric sample with a higher thickness, the doping process slightly increased the conductivity.