Synthesis of Highly Fluorescent All-Conjugated Alternating Donor Acceptor (Block) Copolymers via GRIM Polymerization

Although controlled polymerization procedures for conjugated polymers have considerable advantages with respect to molar mass and end group control, the material scope has been very limited, in particular considering block copolymers and donoracceptor type all-conjugated polymers, imposing considerable challenges upon the synthetic polymer community. In this work, a pushpull monomer consisting of a thiophene (donor) and a pyridine (acceptor) unit is synthesized and subsequently polymerized via Kumada catalyst-transfer polymerization using a nickel catalyst (GRIM polymerization). In this way, an alternating donoracceptor copolymer is obtained via a chain-growth mechanism. Furthermore, an all-conjugated block copolymer containing a poly(3-hexylthiophene) block and the alternating copolymer is successfully prepared in a one-pot procedure as well. The diblock structure is confirmed by comparison of the thermal, electrochemical, and spectroscopic properties of the block copolymer and its constituting polymer parts.