Electrochemical AFM on surface grafted poly(ferrocenylsilanes)

Ethylenesulfide and trimethylenesulfide end-functionalized poly(ferrocenyld imethylsilanes) CES-PFS and TMS-PFS) with different degrees of polymerizati on were prepared via anionic ring-opening polymerization. Molecular charact erization of ES-PFS was carried out by using H-1-NMR, GPC, FTIR, and elemen tal analysis. Thin films of ES-PFS were prepared by immersing gold(111) sub strates into 1.0 mg/ml solutions of the polymers in toluene. The polymeric films were characterized by FTIR, XPS, and contact angle measurements. Thic knesses of the grafted films were measured by SPR. Thicknesses determined b y SPR and the theoretically calculated values are in a reasonable agreement . The morphology of the films was studied by tapping mode AFM. The electroc hemical behavior of the films was monitored by cyclic voltammetry (CV). CVs show two reversible redox peaks, indicating a stepwise oxidation of the ir on atoms in the polymer chains. Scanning Electrochemical Force Microscopy ( SEFM) allowed us to study in situ the morphological changes occurring in th e film upon electrochemical oxidation or reduction. AFM images indicated th at in the oxidized form the chains were stretched due to electrostatic repu lsion.