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 amodel small molecule system is carried out to develop suitableconditions for the direct arylation polymerization (DArP) of fluorinatedcopolymers, which are incompatible with conditionspreviously utilized successfully for nonfluorinated systems. Themodel system features a coupling between a 2-substituted thiopheneand a pentafluorobenzene, where one of the partnerswas brominated. A substantial difference in reactivity isobserved, demonstrating that the optimal functionalization fordirect arylation between a thiophene-based donor and a highlyfluorinated acceptor is a halogenated thiophene and anunfunctionalized fluorinated unit, which is opposite of typicalcross coupling reactions, where the acceptor is typicallyhalogenated. The best conditions are applied to the copolymerizationof 1,2,4,5-tetrafluorobenzene and 2,2’-(2,5-bis((2-hexyldecyl)oxy)21,4-phenylene)dithiophene. Polymers arefree of β-defects and significant homocoupling. This work furtherunderscores the attractive simplicity, relevance, and easeof DArP while reconfirming its broad compatibility withincreasingly popular fluorinated copolymers.