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The α-diimine late transition metal catalyst represents a new strategy for the synthesis of atactic polypropylene elastomer. Taking into account the properties of the material, enhancing the molecular weight of polypropylene at an elevated temperature through modifying the catalyst structure, and further increasing the activity of α-diimine catalyst for propylene polymerization, are urgent problems to be solved. In this work, two α-diimine nickel(II) catalysts with multiple hydroxymethyl phenyl substituents were synthesized and used for propylene homopolymerization. The maximum catalytic activity was 5.40 × 105 gPP/molNi·h, and the activity was still maintained above 105 gPP/molNi·h at 50 °C. The large steric hindrance of catalysts inhibited the chain-walking and chain-transfer reactions, resulting in polypropylene with high molecular weights (407~1101 kg/mol) and low 1,3-enchainment content (3.57~16.96%) in toluene. The low tensile strength (0.3~1.0 MPa), high elongation at break (218~403%) and strain recovery properties (S.R. ~50%, 10 tension cycles) of the resulting polypropylenes, as well as the visible light transmittance of approximately 90%, indicate the characteristics of the transparent elastomer. [ABSTRACT FROM AUTHOR]

Heterogenization of nickel‐based olefin polymerization catalysts has received increasing attention in recent years. In this contribution, positional heterogenization effect in salicylaldimine nickel catalyzed ethylene polymerization is studied. The salicylaldimine nickel pre‐catalysts bearing anchor groups are synthesized, characterized, and investigated in heterogeneous catalytic ethylene polymerization. The anchoring groups are installed at different positions, including the 4‐position of the salicylaldehyde moiety and the 4‐position of the aniline moiety. It is shown that the positions of the anchoring groups have significant effects on heterogeneous ethylene polymerization catalyzed by SiO2‐supported salicylaldimine nickel catalysts. This provides a strategy worth considering for the design of high‐performance heterogeneous catalysts in the future. [ABSTRACT FROM AUTHOR]

In this study, copolymers of 1-butene with allyltrimethylsilane (TMAS) were synthesized via rac-ethylenebis(indenyl)zirconium chloride (rac-Et(Ind)2ZrCl2)/methylaluminoxane (MAO) catalyst. Combining 1H-NMR and Fourier transform infrared (FT-IR) spectroscopies, the microstructure of the copolymer was verified and the insertion rate of TMAS was calculated. Herein, we demonstrate that the isotacticity and thermal decomposition temperature of the copolymers decreased with the contents of allyltrimethylsilane in the copolymers. After blending the resultant copolymers with high isotactic poly(1-butene) powder (HI-PB), it was found that the 1-butene-allyltrimethylsilane copolymer (PB-TMAS) reduced the crystallization temperature, inhibited the formation of form I in the amorphous region at the initial stage of crystal transformation, and slowed down the crystalline transformation from form II to form I, but did not affect the time of the initial reduction of form II. [ABSTRACT FROM AUTHOR]

In this paper, nanorod CeO2 supports were prepared by hydrothermal method using Ce(NO3)3 ⋅ 6H2O as raw material. CuOx/CeO2‐r materials were prepared by calcination using Cu salt‐loaded CeO2‐r supports as raw materials. The three‐component coupling reaction of phenylacetylene, amine and aldehyde was successfully catalyzed by CuOx/CeO2‐r material as a non‐homogeneous catalyst, which showed good catalytic activity. Furthermore, a series of indolizine derivatives can be obtained in higher isolated yields by replacing benzaldehyde with pyridinecarbaldehyde and catalyzing the three‐component synthesis with the same CuOx/CeO2‐r material. The synthesis mechanisms of propargylamine and indolizine were discussed. It is worth noting that the CuOx/CeO2‐r material system is provided for two three‐component reactions, and has the advantages of less catalyst dosage, short reaction time, simple post‐treatment, and a wide range of substrates. [ABSTRACT FROM AUTHOR]