Ambient Direct Arylation Polymerization

Doktorsavhandling, 2025

Conjugated polymers hold a vast array of applications as organic semiconductors owing to their light weight, flexibility and tunability. This enables their implementation in wearable and implantable devices, advancing next-generation bioelectronics through their use as organic mixed ionic-electronic conductors (OMIECs) in organic electrochemical transistors (OECTs). Though promising materials, conjugated polymers often require lengthy, toxic, and energy-intensive syntheses. To develop sustainable technologies, environmentally benign synthesis at large scale to high-performance conjugated polymer materials is essential. This thesis covers the synthesis of conjugated polymers, addressing green chemistry principles and the production/performance trade-off, along with their subsequent evaluation as OMIEC materials.

Direct arylation polymerization (DAP) is a promising green synthesis method to conjugated polymers but still requires high temperatures, toxic solvents and is prone to side reactions. Optimization of DAP parameters led to ambient direct arylation polymerization (ADAP), an open-flask, room-temperature, green-solvent process, yielding over 100 grams of polymer. Mechanistic studies reveal a bimetallic Pd/Pd catalytic system with an initial homocoupling initiation cycle that allows the reaction to proceed at lower temperatures. Unexpectedly, improved structural order arose from the created homocoupling defects, which led to state-of-the-art performance in OECTs. Batch-to-batch variation was addressed by translating ADAP to a continuous droplet-flow reactor. As the reaction in flow tolerated high water content, fully aqueous synthesis was explored using water-soluble monomers and catalysts, showing promising results. Given the robustness of ADAP, instructions for cost-effective synthesis and application teaching labs are outlined, allowing students from diverse scientific backgrounds to engage with advanced polymer chemistry.

Ultimately, the cost, safety and scalability considerations developed throughout this work will aid the advancement of conjugated polymer synthesis.