INSITU INVESTIGATION OF ELECTROPOLYMERIZED POLYANILINE FILMS BY SCANNING-TUNNELING-MICROSCOPY

Electrolytic Scanning Tunneling Microscopy (STM) was used to investiga te in situ the nm- to mum-scale morphology of Polyaniline films prepar ed by potentiodynamic electrochemical polymerization of aniline in pre sence of p-phenylenediamine in 1M HClO4 and 1M HCl. The measurements w ere assisted by ex situ Scanning Electron Microscopy. By choosing an a ppropriate potential of the tunneling tip, it is possible to perform S TM directly in the electropolymerization solution and to image film gr owth sequences. In the sub-mum-scale, the films exhibit a granular mor phology, where the average diameter of the granular growth patterns is affected by the polymerization electrolyte. In the mum-scale it is ob served that the 3D morphology of the films is markedly influenced by t he voltammetric scan rate during electropolymerization, leading to mor e compact films with less fibrous features at very high scan rates of 50 V/s.