High-Throughput Experimentation in Atom Transfer Radical Polymerization: A General Approach Toward a Directed Design and Understanding of Optimal Catalytic Systems
作者：Huiqi Zhang, Veronica Marin, Martin W. M. Fijten, Ulrich S. Schubert*
關(guān)鍵字：Atom transfer radical polymerization, high-throughput, optimal catalytic systems
論文來源：期刊
具體來源：Journal of Polymer Science Part A Polymer Chemistry 2004, 42(8):1876-1885.
發(fā)表時間：2004年
High-throughput experimentation (HTE) was successfully applied in atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) for the rapid screening and optimization of different reaction conditions. A library of 108 different reactions was designed for this purpose, which used four different initiators [ethyl 2-bromoisobutyrate, methyl 2-bromopropionate, (1-bromoethyl)benzene, and p-toluenesulfonyl chloride], five metal salts (CuBr, CuCl, CuSCN, FeBr2, and FeCl2), and nine ligands (2,2′-bipyridine and its derivatives). The optimal reaction conditions for Cu(I) halide, CuSCN, and Fe(II) halide-mediated ATRP systems with 2,2′-bipyridine and its 4,4′-dialkyl-substituted derivatives as ligands were determined. Cu(I)-mediated systems were better controlled than Fe(II)-mediated ones under the examined conditions. A bipyridine-type ligand with a critical length of the substituted alkyl group (i.e., 4,4′-dihexyl 2,2′-bipyridine) exhibited the best performance in Cu(I)-mediated systems, and p-toluenesulfonyl chloride and ethyl 2-bromoisobutyrate could effectively initiate Cu(I)-mediated ATRP of MMA, resulting in polymers with low polydispersities in most cases. Besides, Cu(I) halide-mediated ATRP with 4,5′-dimethyl 2,2′-bipyridine as the ligand and p-toluenesulfonyl chloride as the initiator proved to be better controlled than those with 4,4′-dimethyl 2,2′-bipyridine as the ligand, and polymers with much lower polydispersities were obtained in the former cases. This successful HTE example opens up a way to significantly accelerate the development of new catalytic systems for ATRP and to improve the understanding of structure–property relationships of the reaction systems.