Sustainable Synthesis of a Fluorinated Arylene Conjugated Polymer via Cu-Catalyzed Direct Arylation Polymerization (DArP)

Direct arylation polymerization (DArP) has enabled the more sustainable synthesis of conjugated polymers through the reduction of waste, elimination of toxic and hazardous byproducts, and through the reduction of overall synthetic steps. However, DArP methodologies have almost exclusively relied on the use of noble metal catalysts, such as those with Pd, counter to the efforts toward sustainability. Herein, we report the optimized synthesis of a flourinated arylene conjugated copolymer via DArP using a low-cost, sustainable copper catalyst. Through optimization of the polymerization conditions, we are able to lower the loading of the catalyst from 50 to 5 mol %. As an example, we are able to obtain molecular weights of 16.4 kDa, accompanied by a yield of 54%, with a loading of only 5 mol % for the Cu catalyst. The synthesized polymers were characterized using H-1 and F-19 NMR spectroscopy, showing agreement with those previously prepared with a minimization or exclusion of defects. This work also demonstrates that Cu-catalyzed DArP methodologies can be compatible with substrates that do not possess directing groups, which can help to facilitate C-H functionalization, allowing for a broadening of substrate scope.