Fabrication of Polypyrrole Functional Nanofilms by Nucleophilic Addition—Part I: Synthesis and Characterization

Abstract

Polypyrrole (PPy) nanofilms were deposited by in situ chemical oxidative polymerization on polyethylene or polypropylene. The thickness is determined by SEM of the cross-section. Thin thickness nanofilms (180 ± 5 nm) are deposited. The nanofilms are then modified by nucleophilic addition to attach functional groups to the nanofilms. Strong nucleophiles (e.g., thiols) react by conventional heating. Weak nucleophiles (e.g., nitroanilines) only react when applying microwaves. The spectroscopic (UV–visible, FTIR, XPS and XANES) characterization shows the attachment of functional groups and the change in electronic properties upon the reaction. The conductivity of the functionalized PPy nanofilms are lower than unmodified PPy nanofilms, likely due to steric effects on the extended conjugation and disturbance of the electron hopping between chains. While reaction with some nucleophiles (e.g., bisulfite ion) makes nanofilms more hydrophilic, modification with long alkyl chains or fluorinated long chains produces highly hydrophobic nanofilms. No noticeable effect of the reaction on the film thickness is observed, suggesting little or no loss of polymer due to dissolution.