Catalyst transfer polymerization

[1] Benefits to using CTP over other methods are low polydispersity and control over number average molecular weight in the resulting polymers.

[2] The first reports of CTP came simultaneously from the labs of Yokozawa[3] and McCullough[4] in 2004, with the recognition that polythiophene can be synthesized with low dispersity and with control over molecular weight.

The catalyst can isomerize to other π-complexes via a process known as "ring-walking" to the π-bond adjacent to a C-X bond at the end of the chain allowing oxidative addition to occur.

[5] The propagation steps of CTP occurs through a cycle of transmetalation, reductive elimination, ring walking, and oxidative addition.

[6] A characteristic of CTP is living chain-growth character, meaning that the catalyst will have a reactive chain end for the entirety of the polymerization.

Current research into CTP focuses on finding catalysts that form strong catalyst-polymer π-complexes such that the polymerization remains living.