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Poly(2,5-dimethoxyaniline) (PDMOA) and its copolymers with aniline (PADMOA), which exhibit remarkably improved solubility in common organic solvents, were obtained by chemical polymerization, and characterized by a host of physical techniques. The lowering of the quinoid absorption in the IR spectra and the upshifting of the N 1s envelope in the XPS spectra indicate residual doping in the XPS polymers and thermal characteristic of the polymers provide evidence for hydrogen bonding, which appear to enhance the thermal stability of the homopolymer. These polymers are highly planar and conjugated, with well-developed polaronic features, shown by the XRD, ESR and UV-spectral data. The conductivity, however, is not high and apparently may be due to localization of polaronic charges at the hydrogen-bonding sites and the increased proportion of the insulating methoxy component in the polymer matrix.

Polyaniline (PAN), poly(o-bromoaniline) (POBA), and poly(aniline-co-o-bromoaniline) (PABA) were synthesized by oxidative coupling. These polymers are protonated by 10 -20% methane sulfonic acid (MSA) and 1M HCl. The new polymer bases have greater solubility than that of PAN in common polar organic solvents; PAN-MSA was observed to be the most thermally stable of these polymers. POBA is associated with residual quinoid diimine units as illustrated in the IR and UV-vis spectra, after reduction with hydrazine dihydrochloride. Both the doping agents cause a downward shift of the quinoid absorption in the IR spectra. MSA-and HCl-doped PAN and PABA polymers exhibit a coil-like conformation in DMSO, whereas only MSA-doped PAN and PABA show an "expanded coillike" conformation in m-cresol with a "free carrier tail" above 800 nm in their electronic spectra. XPS spectra indicated the presence of covalent bromine in the POBA and PABA polymers. Bromine retention was greater in the homopolymer as evidenced by the IR studies after aging at 350°C. Compared to HCl, MSA is found to be a more effective dopant, enhancing the conductivity of the copolymers by 10 2 -10 3 times in magnitude.