Internal donors on supported Ziegler Natta catalysts for isotactic polypropylene: a brief tutorial review

Abstract

The scientific and technical advances in the field of polymer science has been abundant in recent years. Amongst the various polymeric materials available in market, synthesis of polyolefins has been in the forefront since decades. A major challenge in this domain remains in attaining stereoregular polyolefins especially polypropylene (PP) and significant efforts were carried out by synthesizing various internal donors (ID) aiding the catalysts involved in producing them. This short review gives an overview of i) various generations of Ziegler–Natta (ZN) catalyst systems ii) general classes of ID that has been demonstrated by the researchers over the past decades iii) their influence on PP isotacticity and polymer properties. The coordination modes of different donor classes on supported ZN system and comparative study especially between phthalate and diether ID classes were also addressed here. This review also presents the studies carried out on phthalate catalyst structure analysis, detailed comparison study on phthalate and diether IDs in terms of PP isotacticity, regioselectivity, hydrogen response, and also their cross combination study and competitive behavior. Further a brief description on other structurally varied IDs like malonates, maleates, silyl diol esters, bifunctional donors, multi ether donors demonstrated for isotactic PP were also presented. Studies conducted on compatibility of incorporation of two different classes of IDs on a single supported ZN system for the fundamental understanding of the catalyst behavior; and also on how mixed donor approach enables in tuning the catalyst for polymer properties were also presented. This review also provides an opportunity to the young minds and the basic researchers from academic point of view by and large to create new polymeric materials with useful properties or modify the existing materials for new applications by incorporating new IDs for further improvisation of the stereo regularity in obtaining the polymers. Graphic Abstract

Polyolefin Catalyst Research: A Product‐Driven Industrial Perspective

“…Additionally, the country has a vast number of polyolefin compounding and plastics processing industries. Therefore, from a total perspective and on principle, Saudi Arabia requires [69] 2018 Laboratory reactors and procedures for catalyst evaluation (book chapter) [70] 2018 Scale-up of catalyst recipes to commercial production (book chapter) [71] 2018 Supported titanium/magnesium Ziegler-Natta catalysts for producing polyethylene (book chapter) [72] 2018 Stereospecific α-olefin polymerization with heterogeneous catalysts (book chapter) [73] 2018 MgCl 2 -supported Ti catalysts to produce morphology-controlled polyethylene (book chapter) [74] 2018 Phillips chromium catalyst for ethylene polymerization (book chapter) [75] 2018 An up-to-date and advanced compendium on industrial polyethylene and technology (handbook) [76] 2019 Developments in supported polyolefin catalysts, and chronological developments of new precatalysts (metallocenes and nonmetallocenes) and iPP donors commercialized by major polyolefin producers (book chapter) [77] 2019 Development of supported catalysts, particularly for multimodal polyolefins and manufacture processes (book) [78] 2020 Ultrahigh molecular weight polyethylenes: catalysts (ZÀ N, metallocene, and post-metallocene), structure, properties, processing, and applications (review) [79] 2020 Versatile polypropylenes with tunable molecular structure using tailor-made catalysts, and recent commercial level i-PP metallocenes, postmetallocenes, internal and external donor disclosures, and PP processes (book chapter) [24] 2021 Advancement on industry-relevant stereoselective propylene catalysts using C 1 symmetric Group 4 ansa-metallocenes having multi-substituted cyclopentadienyl-fluorenyl (CpÀ Flu) ligands (personal account and review) [80] 2021 PP ZÀ N catalysts, internal donors, and their influence on PP isotacticity and properties (review) [81] 2021 Recent developments regarding ZÀ N internal and external donors, cocatalyst chemistry, polyolefin fibre, composite, foam, blend, and 3D printing products (review) [82] 2021 Surfactant-aided emulsion process for the in-situ synthesis of spheroidal MgCl 2 -supported ZÀ N catalyst (a very recent contribution)…”

“…Table 1 chronologically lists 36 reviews, 20 books and book chapters, and 2 editorials, [26–82] published on polyolefin catalysts during 1997 to 2021. Additionally, Table 4 in appendix of Grimmer and Coville [32] includes 30 reviews on single‐site polyolefin catalysts during 1991–2000.…”

Porous Organic Polymers-Supported Zeigler-Natta Catalysts for Preparing Highly Isotactic Polypropylene with Broad Molecular Weight Distribution

“…Among them, the impact of the extra addition of electron donors to improve the overall performance of the supported Z–N catalysts has been distinguished. The addition of extra electron donors or Lewis bases on the MgCl 2 /TiCl 4 surface could dramatically improve the polymerization activity, stereoselectivity and catalyst morphology, and regulate hydrogen response and molecular weight distribution by modulation of the chemical environment, content and dispersion of Ti metal sites, and the MgCl 2 crystalline size in the supported Ziegler–Natta catalysts [ 10 , 11 , 12 ]. For recent decades, much attention has been focused on the design and fabrication of catalysts support, and on novel electron donors and their interaction mechanisms with active sites in the supported MgCl 2 based PP catalysts [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ].…”

Multivariable Rheological Models for Commercial Polypropylene with High Molar Masses

“…with the production of nearly 50 million tons/year over the world. [ 3 ] This large production is mainly a result of the high demand of society which stimulates several industrial sectors, such as food packaging, civil construction, automotive, and electric and electronic components. To reach the final application, PP needs to pass a melted stage where different grades are subjected to various conditions such as high shear deformation and relatively high temperature leading to molecular degradation and structural development as well as flows through narrow and complex geometries (such as single and twin screw), commonly observed in extrusion processes.…”