Copolymers of aniline and 3-aminophenol derivatives with oligo(oxyethylene) side chains as novel water-soluble conducting polymers

A novel water-soluble copolymer of aniline and aminophenol (AP) grafted with oligo(oxyethylene) (PEO) side chains (AP-g-PEO) was synthesized. The AP-g-PEO macromononer was prepared starting from an N-protected 3-aminophenol (protection group: tert-butoxycarbonyl) followed by the substitution of tosylated oligo(oxyethylene) on the hydroxide moiety of the AP and deprotection. Finally, AP-g-PEO was copolymerized with aniline at various feed mole ratios (AP-g-PEO/aniline). The copolymers and various intermediates were characterized by FTIR, MS, NMR, GPC, UV-vis, and chemical elemental analysis. The increase of the aniline content and the decrease of the PEO side chain length generated lower oligo(oxyethylene) grafted concentrations and solubilities in water but longer conjugation lengths and higher conductivities. Four AP-g-PEOs were prepared from four oligo(oxyethylene) methyl ethers with M-n = 164, 350, 750, and 2000. The poly((AP-g-PEO-750)-co-aniline) at a feed mole ratio of 3/1 was water-soluble and possessed a relatively high conductivity (0.12 S/cm). AP-g-PEOs were found to have low reactivities and to generate low homopolymerization degrees because of the torsional effects of the PEO side chains on the backbone of the copolymer. A possible copolymerization mechanism was suggested. Furthermore, the copolymers with high PEO content had lower oxidation and doping levels of their backbones, which were confirmed by X-ray photoelectron spectroscopy.