Flow Synthesis of Organic Electronic Materials
In 2012 we first reported a stable droplet flow reactor for the preparation of poly(3-hexylthiophene) (P3HT) —one of the principle polymeric semiconductors used throughout organic electronics research.
Our droplet-flow approach sees the reaction phase dispersed into an inert perfluorinated "carrier" oil to form a stream of near-identical microlitre-sized droplets. Each droplet behaves like a microlitre flask where rapid heat and mass transfer ensure a highly uniform and reproducible reaction environment. Importantly, the carrier oil preferentially wets the PTFE reactor walls and thereby prevents the reaction phase from contacting the wall, which invariably leads to reactor fouling in continuous flow analogues.
A video of the polymerisation of P3HT is shown below. Here, the droplets—containing monomer and catalyst—enter the heated reactor in the centre of the spiral, where polymerisation is initiated. The reaction proceeds rapidly inside the droplets resulting in a colour change from yellow through to deep red. The polymer is then collected into a protic solvent and isolated over a filter.