In this study, a series of polar functionalized polypropylene materials with tunable molecular weights and high incorporation ratios were synthesized by copolymerizing propylene and various polar monomers (MA, AA, BA, 6FA and HA) using some elaborate iminopyridyl Pd(II) catalysts. In propylene homopolymerization, the rotation-restricted substituent variations of the Pd(II) catalysts are observed to have a systematic influence on the polymerization reaction with respect to the molecular weight of the polymer (Pd1-free rotation: 0.4–0.5 kg mol⁻¹, Pd2-restricted rotation: 0.6–0.8 kg mol⁻¹ and Pd3-fixation: 2.6–31.4 kg mol⁻¹). More importantly, compared with the classical α-diimine palladium catalyst, iminopyridyl Pd(II) catalysts with 8-aryl naphthyl or dibenzosuberyl substituents can lead to a significantly higher molecular weight (M_w up to 99.6 kg mol⁻¹). Meanwhile, the ligand structure of the catalysts can significantly affect the microstructure (BD: 94–251/1000C) of the obtained polypropylene. A similar tendency is also observed during the copolymerization of propylene with polar monomers. Most importantly, iminopyridyl Pd(II) catalysts can produce various polar functionalized polypropylene materials with significantly higher incorporation ratios (up to 30.6 mol%) in comparison to the classical α-diimine palladium catalyst. The semi-open structure of the iminopyridyl ligand allowed the large propylene and polar monomer molecules to easily coordinate to the metal center, thus, leading to an adequate incorporation in the polymer chains.

中文翻译：

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直接合成具有可调分子量和高掺入率的各种极性功能化聚丙烯材料

在这项研究中，通过使用一些精心制作的亚氨基吡啶基 Pd( II ) 催化剂将丙烯和各种极性单体（MA、AA、BA、6FA和HA）共聚，合成了一系列具有可调分子量和高掺入率的极性官能化聚丙烯材料。在丙烯均聚中，观察到Pd( II ) 催化剂的旋转受限取代基变化对聚合反应相对于聚合物的分子量有系统的影响（Pd1自由旋转：0.4-0.5 kg mol ^-1 , Pd2-限制旋转：0.6-0.8 kg mol ^-1和Pd3 -固定：2.6-31.4 kg mol ^-1）。更重要的是，与经典的 α-二亚胺钯催化剂相比，具有 8-芳基萘基或二苯并辛基取代基的亚氨基吡啶基 Pd( II ) 催化剂可导致显着更高的分子量（M _w高达 99.6 kg mol ^-1）。同时，催化剂的配体结构会显着影响所得聚丙烯的微观结构（BD：94-251/1000C）。在丙烯与极性单体的共聚过程中也观察到类似的趋势。最重要的是，亚氨基吡啶基 Pd( II) 催化剂可以生产各种极性官能化聚丙烯材料，与经典的 α-二亚胺钯催化剂相比，具有显着更高的掺入率（高达 30.6 mol%）。亚氨基吡啶配体的半开放结构使大丙烯和极性单体分子很容易与金属中心配位，从而导致在聚合物链中充分掺入。