Selenium Dioxide Catalyzed Polymerization of N-doped Poly(benzodifurandione) (n-PBDF) and Its Derivatives

The recent discovery of highly conductive, solution-processable, n-doped poly(benzodifurandione) (n-PBDF) marks a milestone in the development of conducting polymers. Currently, n-PBDF is prepared by either duroquinone-mediated or copper-catalyzed polymerizations, where scalability and cost-effectiveness may present challenges. Here, we report a general, scalable, and cost-effective method for n-PBDF and its derivatives, namely selenium dioxide (SeO₂) catalyzed polymerization. We discovered that a catalytic amount of selenium dioxide leads to high monomer conversions (>99 % by NMR). The obtained n-PBDF exhibits a consistently narrow hydrodynamic diameter distribution and its thin films show high conductivities. Furthermore, we revealed that this polymerization involves a mechanism distinct from the previously reported radical pathway. It involves successive Riley oxidation and aldol polycondensation processes. It was also found that the reduced selenium precipitates from dimethyl sulfoxide (DMSO) when the catalytic cycle is terminated, allowing for a straightforward purification process through centrifugation and filtration. This method thus eliminates the need for the costly and slow dialysis process. Finally, we demonstrated that SeO₂ catalyzed polymerization is applicable to n-PBDF derivatives, proving the generality of this method.