Approaches for Improving the Sustainability of Conjugated Polymer Synthesis using Direct Arylation Polymerization (DArP)
Direct arylation polymerization (DArP) provides a more sustainable alternative to conventional methods for conjugated polymer synthesis, such as Stille-Migita or Suzuki-Miyura polymerizations. DArP proceeds through a C-H activaiton pathway, allowing for a reduction in the synthetic steps needed to access the monomer, since the installation of a transmetallating reagent, such as an organostannane or organoboron, is not required. However, compared to small-molecule synthesis, the prevalent conditions employed for DArP still require hazardous or unsustainably sourced reaction components, such as the solvent and transition-metal catalyst. This mini-review highlights recent work on the implementation of sustainable solvents, transition metal catalysts, and overall polymerization methods for DArP. The extension of small-molecule direct arylation conditions towards polymer synthesis is also discussed, along with the associated challenges, mechanistic considerations, and outlook for future work.