Synthesis, characterization, and olefin (co)polymerization behavior of unsymmetrical α-diimine palladium complexes containing bulky substituents at 4-position of aniline moieties

Publication date: Available online 20 September 2018Source: Journal of Organometallic ChemistryAuthor(s): Lihua Guo, Yanlan Liu, Wenting Sun, Qing Du, Yuliang Yang, Wenyu Kong, Zhe Liu, Darui ChenAbstractThree novel unsymmetrical α-diimine Pd(II) complexes containing bulky substituents at 4-position of aniline moieties were prepared and characterized. Unfortunately, the introduction of large substituents on para- N-aryl moieties did not slow the exchange between the anti and syn forms for these complexes. These unsymmetrical α-diimine Pd(II) complexes also did not improve thermal stability and broaden molecular weight distribution in ethylene polymerization. However, these α-diimine palladium catalysts could copolymerize ethylene with biorenewable comonomer acrylic acid (AA), with comonomer incorporation in the range of 1.1–2.7% and high copolymer molecular weights. The AA units are incorporated predominately at the end of the branches. In addition, a systematic investigation on the polymerization of 1-hexene, 1-octene and 1-decene using these complexes was also performed. Changes in the ligand sterics and monomer length can influence the branch density and molecular weight of poly(α-olefins). Interestingly, these α-olefin polymers show properties characteristic of thermoplastic elastomers, i.e., good elastomeric recovery and high strain at break. Pervious work has shown that ethylene or α-olefin polymerization using some nickel α-diimine catalysts can generate elast...

Source: Journal of Organometallic Chemistry - September 21, 2018 Category: Chemistry Source Type: research