Organic chemical reactions have been used to functionalize preformed conducting polymers (CPs). The extensive work performed on polyaniline (PANI), polypyrrole (PPy), and polythiophene (PT) is described together with the more limited work on other CPs. Two approaches have been taken for the functionalization: (i) direct reactions on the CP chains and (ii) reaction with substituted CPs bearing reactive groups (e.g., ester). Electrophilic aromatic substitution, S_EAr, is directly made on the non-conductive (reduced form) of the CPs. In PANI and PPy, the N-H can be electrophilically substituted. The nitrogen nucleophile could produce nucleophilic substitutions (SN) on alkyl or acyl groups. Another direct reaction is the nucleophilic conjugate addition on the oxidized form of the polymer (PANI, PPy or PT). In the case of PT, the main functionalization method was indirect, and the linking of functional groups via attachment to reactive groups was already present in the monomer. The same is the case for most other conducting polymers, such as poly(fluorene). The target properties which are improved by the functionalization of the different polymers is also discussed.

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.