Self-assembled polyaniline thin films: Comparison of poly(styrene sulphonate) and oligonucleotide as a polyanion

An electrostatic self-assembly process based on layer-by-layer deposition was employed to prepare thin films of charged polyaniline (PANI) and two polyanions: poly(styrene sulphonate) (PSSA) and an 18-base oligonucleotide (ON). The concentrations of polyion depositing solutions were varied and the effect on the thin films' properties was examined. The layer-by-layer deposition was monitored by means of UV–Vis spectroscopy, and it was shown that in all investigated cases the deposition of bilayers is linear in respect to the number of deposited bilayers. The UV–Vis results confirmed that ONs easily incorporate into PANI/ON films. Cyclic voltammetry experiments revealed different electrochemical behaviour of PANI/PSSA and PANI/ON films, with PANI/ON films showing less electroactivity. Scanning Electron Microscopy analysis showed significantly different morphology of those films.