Influence of functionality on direct arylation of model systems as a route toward fluorinated copolymers via direct arylation polymerization (DArP)

A screening of direct arylation conditions on a model small molecule system is carried out to develop suitable conditions for the direct arylation polymerization (DArP) of fluorinated copolymers, which are incompatible with conditions previously utilized successfully for nonfluorinated systems. The model system features a coupling between a 2‐substituted thiophene and a pentafluorobenzene, where one of the partners was brominated. A substantial difference in reactivity is observed, demonstrating that the optimal functionalization for direct arylation between a thiophene‐based donor and a highly fluorinated acceptor is a halogenated thiophene and an unfunctionalized fluorinated unit, which is opposite of typical cross coupling reactions, where the acceptor is typically halogenated. The best conditions are applied to the copolymerization of 1,2,4,5‐tetrafluorobenzene and 2,2'‐(2,5‐bis((2‐hexyldecyl)oxy)?1,4‐phenylene)dithiophene. Polymers are free of β‐defects and significant homocoupling. This work further underscores the attractive simplicity, relevance, and ease of DArP while reconfirming its broad compatibility with increasingly popular fluorinated copolymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2598–2605