Chain-growth polymerization for the synthesis of polyfluorene via Suzuki-Miyaura coupling reaction from an externally added initiator unit

Palladium-catalyzed polycondensation of 2-(7-bromo-9,9-dioctyl-9H-fluoren-2-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (1a) with (Bu3PPd)-Bu-t(Ph)Br (2) via Suzuki-Miyaura coupling reaction was investigated. The polymerization in a mixture of THF and 2 mol/L aqueous solution of Na2CO3 proceeded smoothly at room temperature and afforded well-defined polyfluorenes with narrow molecular weight distributions. MALDI-TOF mass spectroscopy showed that the obtained polymers have a phenyl group at one end. The relationships of conversion to number-average molecular weight (M-n) and feed ratio to M-n were linear. These results demonstrate that this organometallic polycondensation proceeds through a chain-growth polymerization mechanism from an initiator unit derived from the catalyst.