Angelw: copolymerization of ethylene with functional polar endoolefins

1、 Background polyolefin materials have important applications in industry and people's livelihood In addition to the common non-polar olefin polymers such as ethylene and propylene, the polar olefin polymerization, especially the copolymerization process of ethylene and polar olefins, is a hot topic in the field of polyolefin research Since 1987, klabunde and itten developed the shop type nickel catalyst to realize the copolymerization of ethylene with special polar olefins, a variety of nickel and other pre transition metal catalysts have been proved to be able to achieve such copolymerization However, it is difficult to realize the copolymerization of polar olefins with ethylene Functional polar alkenes refer to the functional polar functional groups directly connected to the C = C double bond Due to the strong electron absorption and large potential resistance effect of functional groups, it is difficult for functional polar alkenes to participate in the polymerization Until 1996, Professor Brookhart realized the copolymerization of ethylene and some functional polar olefins with Pd catalyst In 2002, a new Pd catalyst system was used by Drent group to realize the copolymerization of various polar olefins and ethylene, but its insertion rate was low In 2018, the team of Nozaki, Tokyo University, Japan, realized the copolymerization of ethylene with methyl methacrylate or other similar olefins using Pd catalyst developed by the team They found that the coordination process between 1,1-disubstituted olefins and catalysts was greatly affected due to their higher steric resistance compared with mono substituted olefins (photo source: angelw Chem Int ed.) 2 Recently, Professor Chen Changle of University of science and technology of China has creatively realized the copolymerization process of 1,2-disubstituted olefin and ethylene by using single metal Pd catalyst, and successfully realized the preparation of binary copolymer Relevant research results were published on angelw Chem Int ed (DOI: 10.1002/anie 201913088) 3 Research content (picture source: angelw Chem Int ed.) (picture source: angelw Chem Int ed.) The author first used phosphonium sulfonate palladium catalyst for multifunctional 1, The copolymerization process of 2-disubstituted olefins and ethylene was explored It was found that the copolymerization process of trans crotonate methyl ester and crotonate ethyl ester could be realized, with the highest insertion rate of 3.4% The lower melting temperature of the copolymer fully confirmed the successful insertion of polar olefins However, for CIS 1,2-disubstituted olefins, palladium catalyst is difficult to realize the copolymerization process In this paper, the kinetics of copolymerization of ethylene and dimethyl maleate with CIS and trans structure was studied It was found that the K value of copolymerization of trans structure substrate was much higher than that of CIS structure substrate At the same time, the trans structure of dimethyl maleate was successfully prepared From the single crystal structure, CIS alkenes will conflict with catalyst ligands, so it is difficult to realize the coordination process Is it difficult to realize the copolymerization of CIS olefins with ethylene? The answer is No The author creatively solves this problem by using series reaction First, the end olefins were prepared by the decomposition of CIS olefins with Grubbs catalyst at low temperature Then, the decomposition of olefins was inhibited by Grubbs catalyst when the temperature was increased, and the olefin polymerization was carried out quickly with phosphonium sulfonate and palladium catalyst, thus the binary copolymers were prepared It is found that higher insertion rate of polar olefins will have a great influence on the viscosity and other properties of binary copolymers 4 Conclusion the copolymerization of trans 1,2-disubstituted olefins and ethylene is realized, and the copolymerization of CIS disubstituted ethylene and ethylene is realized by series reaction.