Effect of doping on the fabrication of Langmuir and Langmuir-Blodgett films of poly(o-ethoxyaniline)

The properties of Langmuir films are generally dependent on the pH of the subphase. In a previous work, for instance, we observed that Langmuir films from poly(o-ethoxyaniline) (POEA) suitable for Langmuir-Blodgett deposition were only obtained if spread on an acidic subphase. Because POEA is highly soluble in both undoped and doped states, we have now extended these studies to systematically investigate the effect of doping on the fabrication of Langmuir and LB films. The pressure-area isotherms of the Langmuir films display less hysteresis and higher collapse pressures, when the polymer is doped in solution prior to spreading of the monolayer on an acidic subphase. This procedure leads to stable films that can be readily deposited in the form of LB films.