Effect of surface pressure on the insulator to metal transition of a langmuir polyaniline monolayer.

A remarkable change in the conductivity of a polyaniline (PAN) Langmuir monolayer in the conducting state, as a function of surface pressure, has been observed using scanning electrochemical microscopy (SECM). The film conductivity, as expressed by the SECM current response of a redox mediator, was measured in-situ in a Langmuir film balance. The conductivity of the film increases significantly with surface pressure, above a threshold value of ca. 20 mN m-1.