Kumada Catalyst‐Transfer Polycondensation: Mechanism, Opportunities, and Challenges

Abstract

Kumada catalyst-transfer polycondensation (KCTP) is a new but rapidly developing method with great potential for the preparation of well-defined conjugated polymers (CPs). The recently discovered chain-growth mechanism is unique among the various transition metal-catalyzed polycondensations, and has thus attracted much attention among researchers. Most progress is found in the areas of mechanism and external initiation via new initiators, but also the number of monomers other than thiophene that can be polymerized is steadily increasing. Accordingly, the variety of CP chain architectures is increasing as well, and a considerable contribution of KCTP toward more efficient materials can be expected in the future. This review critically focuses on very recent progress in the synthesis of CPs and the mechanism of KCTP, and is finally aimed at providing a comprehensive picture of this exciting polymerization method.

Comparing blends and blocks: Synthesis of partially fluorinated diblock polythiophene copolymers to investigate the thermal stability of optical and morphological properties

“…In the case of P3OT- b -F-P3OT 1:4, the discrepancy likely arises from the fact that the activated M–H monomer is intrinsically comprised of ca. 20% of a regioisomer which is relatively unreactive towards KCTP when using 1,2-bis(diphenylphosphino)propane as ligand [32,46,48–49]. This results in a reduced effective concentration of 2 relative to 4 , since in the case of 4 the regioselectivity of the monomer activation is over 95% [42].…”

“…The Grignard Metathesis (GRIM) polymerization, also known as the Kumada catalyst transfer polymerisation (KCTP), is a popular method to synthesize conjugated block copolymers because its chain growth behavior avoids any issues of triblock copolymers, and also provides good control over the molecular weight and relative block lengths [24–31]. In addition to enabling the formation of a diblock copolymer via sequential monomer addition , the KCTP can lead to controlled end-functionalization [1,28,32]. This has been used as a handle for further applications such as macroinitiation [7,10,21,31,33], endcapping [34], and grafting [35–39].…”

Application of named reactions in polymer synthesis

“…Since the discovery of the chain-growth mechanism in 2004 [22][23][24][25], Kumada polymerization has been considered to be a wellsuited tool for the preparation of well-defined polymers with low polydispersities, controllable molecular weights, and chain-end functionality. A plethora of electron-rich monomers based on thiophene, fluorene, selenophene, pyrrole, benzene, and carbazole have been successfully polymerized using appropriate nickel catalysts, and the properties of the obtained materials matched those expected for a well-controlled polymerization process [28].…”

Gradient Sequence π-Conjugated Copolymers

“…15). This synthetic method, now known as catalyst transfer polycondensation (CTP) (13)(14)(15)(16)(17)(18)(19), paved the way for synthesizing all-conjugated diblock copolymers (20)(21)(22)(23)(24)(25)(26)(27), star polymers (28,29) and surface-grafted polymers (30)(31)(32). CTP also provides access to all-conjugated gradient sequence copolymers (33)(34)(35)(36).…”