title: Crystalline Isotactic Polar Polypropylene from the Palladium-Catalyzed Copolymerization of Propylene and Polar Monomers.
abstract: Moderately isospecific homopolymerization of propylene and the copolymerization of propylene and polar monomers have been achieved with palladium complexes bearing a phosphine-sulfonate ligand. Optimization of substituents on the phosphorus atom of the ligand revealed that the presence of bulky alkyl groups (e.g. menthyl) is crucial for the generation of high-molecular-weight polypropylenes (Mw ≈10(4) ), and the substituent at the ortho-position relative to the sulfonate group influences the molecular weight and isotactic regularity of the obtained polypropylenes. Statistical analysis suggested that the introduction of substituents at the ortho-position relative to the sulfonate group favors enantiomorphic site control over chain end control in the chain propagation step. The triad isotacticity could be increased to mm=0.55-0.59, with formation of crystalline polar polypropylenes, as supported by the presence of melting points and sharp peaks in the corresponding X-ray diffraction patterns.
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ota
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Shingo
authors.identifier: 0000-0003-1776-4608
authors.initials: S
authors.lastname: Ito
authors.affiliation: Japan Polychem Corporation, 1 Toho-cho, Yokkaichi, Mie, 510-0848, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: Japan Polychem Corporation, 1 Toho-cho, Yokkaichi, Mie, 510-0848, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Kitade
authors.affiliation: Japan Polychem Corporation, 1 Toho-cho, Yokkaichi, Mie, 510-0848, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Sakata
authors.affiliation: Japan Polychem Corporation, 1 Toho-cho, Yokkaichi, Mie, 510-0848, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Tayano
authors.affiliation: Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan. nozaki@chembio.t.u-tokyo.co.jp.
authors.forename: Kyoko
authors.identifier: 0000-0002-0321-5299
authors.initials: K
authors.lastname: Nozaki
keywords: homogeneous catalysis; isospecificity; palladium; polymerization; propylene