Global analysis of polyfluorene via AB-type Suzuki–Miyaura polymerization: Empirical and mechanistical rationalization of structural and reaction parameters on molar mass, dispersity and yield

The preparation of conjugated polymers with precisely tuneable opto-electronic properties is based on modern polymerization techniques. In addition to conventional step growth polycondensation for the underlying C−C coupling steps, the Suzuki-Catalyst-Transfer- Polymerization (SCTP) continues to attract great interest, as it enables a chain growth with controlled molar masses, dispersity values and end group fidelity. The combination of these beneficial properties allows for the use in defined block copolymers or as functional building blocks in functional polymer architectures aiming to control energy- and charge transfer at the macromolecular level. For an ideal SCTP mechanism, a ring-walking step is crucial – and many experimental parameters contribute to the overall success of the polymerization to tailor the desired degree of polymerization, low dispersity values and high yields. Many reports explored specific combinations within the available parameter space, yet a unifying analysis to identify limitations as well as promising future directions to advance the synthetic methodologies is needed. In this work, all available experimental data for the AB-type 2,7-linked poly(fluorene) is collected and an algorithmic global analysis is presented, including the tabulated results for machine learning and re-inspection of the collected raw data. It is found that SCTP is typically obeyed for monomer-to-catalyst ratios up to 25, while the combination of a tBu3P-based Pd pre-catalysts and a boronate-based monomers enable excellent SCTP fidelity with monomer-to-catalyst ratios up to 500.