Novel Approach to Introduce Alkyl Chains into PEDOT:PSS and Its Effect on the Performance as a Flexible Electrode

We here report a synthetic route to introduce alky chains into poly (3,4-ethylenedioxythiophene):poly (4-styrenesulfonate) (PEDOT:PSS) by the reaction with epoxyalkanes. The reaction was analyzed by FT-IR, TGA, and XPS studies, and the conductivities of derivatives were discussed as a function of the length of alkyl chains. PEDOT:PSS-C6, which is the product from a reaction with epoxyhexane, was well dispersed in methanol and transparent films from this dispersion were successfully prepared. PEDOT:PSS-C6 film showed an increase in hydrophobicity, resulting in enhanced water resistance compared to pristine PEDOT:PSS film, and a morphological study of the film exhibited clear phase separation similar to PEDOT:PSS doped by DMSO. We also observed an improvement in the conductivity and flexibility of PEDOT:PSS-C6 film compared to those of pristine PEDOT:PSS film. This study proposes a promising method to introduce alky chains into PEDOT:PSS and to develop a flexible electrode applicable to an environment where contact with water is unavoidable.