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Dashti A, Ahmadi M. Recent Advances in Controlled Production of Long-Chain Branched Polyolefins. Macromol Rapid Commun 2024; 45:e2300746. [PMID: 38488683 DOI: 10.1002/marc.202300746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 03/08/2024] [Indexed: 03/24/2024]
Abstract
Polyolefins, composed of carbon and hydrogen atoms, dominate global polymer production. This stems from the wide range of physical and mechanical properties that various polyolefins can cover. Their versatile properties are largely tuned by chain microstructure, including molar mass distribution, comonomer content, and long-chain branching (LCB). Specifically, LCB imparts unique characteristics, notably enhances processability crucial for downstream applications. Tailoring LCB structural features has encouraged academic and industrial efforts, chronicle in this review from a chemistry standpoint. While encompassing post-reaction modification based traditional methods like peroxide grafting, ionizing beam irradiation, and coupling reactions, the main focus is given to catalyst-centric strategies and innovative polymerization schemes. The advent of single-site catalysts-metallocenes and late transition metals catalysts-amplifies interest in tailored chemical methods, but the progress in LCB formation flourishes via tandem catalytic systems and bimetallic catalysts under controlled reaction conditions. Specifically, the breakthrough in coordinative chain transfer polymerization unveils a novel avenue for controlled LCB synthesis by sequential chain propagation, transfer, liberation, and enchainment. This short review highlights recent approaches for the production of LCB polyolefins that can provide a roadmap crucial for researchers in academia and industry, steering their efforts toward further advancements in the production of tailored polyolefin.
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Affiliation(s)
- Arezoo Dashti
- Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran, 159163-4311, Iran
| | - Mostafa Ahmadi
- Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran, 159163-4311, Iran
- Department of Chemistry, Johannes Gutenberg-Universität Mainz, Duesbergweg 10-14, D-55128, Mainz, Germany
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Nifant'ev I, Komarov P, Sadrtdinova G, Safronov V, Kolosov N, Ivchenko P. Mechanistic Insights of Ethylene Polymerization on Phillips Chromium Catalysts. Polymers (Basel) 2024; 16:681. [PMID: 38475365 DOI: 10.3390/polym16050681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 02/28/2024] [Accepted: 02/29/2024] [Indexed: 03/14/2024] Open
Abstract
Silica-supported chromium oxide catalysts, also named Phillips chromium catalysts (PCCs), provide more than half of the world's production of high- and medium-density polyethylenes. PCCs are usually prepared in the Cr(VI)/SiO2 form, which is subjected to reductive activation. It has been explicitly proven that CO reduces Cr(VI) to Cr(II) species that initiate ethylene polymerization; ethylene activates Cr(VI) sites as well, but the nature of the catalytic species is complicated by the presence of the ethylene oxidation products. It is widely accepted that the catalytic species are of a Cr(III)-alkyl nature, but this common assumption faces the challenge of "extra" hydrogen: the formation of similar species under the action of even-electron reducing agents requires an additional H atom. Relatively recently, it was found that saturated hydrocarbons can also activate CrOx/SiO2, and alkyl fragments turn out to be bonded with a polyethylene chain. In recent years, there have been numerous experimental and theoretical studies of the structure and chemistry of PCCs at the different stages of preparation and activation. The use of modern spectral methods (such as extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES), and others); operando IR, UV-vis, EPR, and XAS spectroscopies; and theoretical approaches (DFT modeling, machine learning) clarified many essential aspects of the mechanisms of CrOx/SiO2 activation and catalytic behavior. Overall, the Cosse-Arlman mechanism of polymerization on Cr(III)-alkyl centers is confirmed in many works, but its theoretical support required the development of nontrivial and contentious mechanistic concepts of Cr(VI)/SiO2 or Cr(II)/SiO2 activation. On the other hand, conflicting experimental data continue to be obtained, and certain mechanistic concepts are being developed with the use of outdated models. Strictly speaking, the main question of what type of catalytic species, Cr(II), Cr(III), or Cr(IV), comes into polymerization still has not received an unambiguous answer. The role of the chemical nature of the support-through the prism of the nature, geometry, and distribution of the active sites-is also not clear in depth. In the present review, we endeavored to summarize and discuss the recent studies in the field of the preparation, activation, and action of PCCs, with a focus on existing contradictions in the interpretation of the experimental and theoretical results.
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Affiliation(s)
- Ilya Nifant'ev
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
- Department of Chemistry, M.V. Lomonosov Moscow University, 1-3 Leninskie Gory, 119991 Moscow, Russia
| | - Pavel Komarov
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
| | - Guzelia Sadrtdinova
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
- Faculty of Chemistry, National Research University Higher School of Economics, Myasnitskaya St. 20, 101100 Moscow, Russia
| | | | | | - Pavel Ivchenko
- A.V. Topchiev Institute of Petrochemical Synthesis RAS, 29 Leninsky Pr., 119991 Moscow, Russia
- Department of Chemistry, M.V. Lomonosov Moscow University, 1-3 Leninskie Gory, 119991 Moscow, Russia
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Meirelles JV, de Almeida RF, Morgado AJ, de Castro TB, Rocha RCC, Hauser-Davis RA, Saint'Pierre TD. Metal and metalloid content, bioavailability and sorption processes in glitter and raw glitter materials and associations with human and ecological risk concerns. J Trace Elem Med Biol 2024; 82:127350. [PMID: 38134493 DOI: 10.1016/j.jtemb.2023.127350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 11/24/2023] [Accepted: 11/30/2023] [Indexed: 12/24/2023]
Abstract
BACKGROUND Microplastics comprise a significant group of emerging environmental contaminants with the capacity to adsorb several contaminants. These, in turn, undergo bioaccumulation and biomagnification processes throughout aquatic trophic chains. METHODS Glitter, a microplastic powder composed of a combination of polymers, and raw glitter materials were investigated herein concerning metal and metalloid content, bioavailability, and sorption processes by inductively coupled plasma mass spectrometry (ICP-MS). RESULTS Metal and metalloid concentrations were higher in glitter than in raw glitter materials, but all were below the limits established by the Brazilian National Health Surveillance Agency. Elements present in glitter originate mainly from pigments and, thus, depend on glitter color. The bioavailability of the determined elements concerning human skin was assessed. Low desorbed concentrations in solution indicate that glitter does not represent a health risk through dermal contact concerning metal and metalloid contamination. However, several elements were shown to undergo significant desorption and adsorption processes. CONCLUSION The findings reported herein indicate seemingly low human health risks from dermal glitter contact but reinforce glitter risks as aquatic environment metal and metalloid transport vectors.
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Affiliation(s)
- J V Meirelles
- Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Gávea, CEP 22453-900 Rio de Janeiro, RJ, Brazil
| | - R F de Almeida
- Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Gávea, CEP 22453-900 Rio de Janeiro, RJ, Brazil
| | - A J Morgado
- Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Gávea, CEP 22453-900 Rio de Janeiro, RJ, Brazil
| | - T B de Castro
- Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Gávea, CEP 22453-900 Rio de Janeiro, RJ, Brazil
| | - R C C Rocha
- Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Gávea, CEP 22453-900 Rio de Janeiro, RJ, Brazil
| | - R A Hauser-Davis
- Laboratório de Avaliação e Promoção da Saúde Ambiental, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Av. Brasil, 4.365, Manguinhos, Rio de Janeiro, Brazil.
| | - T D Saint'Pierre
- Departamento de Química, Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Gávea, CEP 22453-900 Rio de Janeiro, RJ, Brazil.
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The effect of SiO2 calcination temperature and [Si]/[Mg] molar ratio on the performance of bi-supported Ziegler-Natta catalysts in ethylene polymerizations. JOURNAL OF POLYMER RESEARCH 2023. [DOI: 10.1007/s10965-023-03448-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Jin Y, Yang Y, Su C, Wang J, Wang Y, Liu B. Novel Imido‐Cr/Silica Ethylene Polymerization Catalysts Modified from the Phillips Catalyst. MACROMOL REACT ENG 2022. [DOI: 10.1002/mren.202200025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Yulong Jin
- Key Laboratory for Biobased Materials and Energy of Ministry of Education Guangdong Laboratory for Lingnan Modern Agriculture College of Materials and Energy South China Agricultural University Wushan Road 483 Guangzhou 510630 People's Republic of China
| | - Yang Yang
- Key Laboratory for Biobased Materials and Energy of Ministry of Education Guangdong Laboratory for Lingnan Modern Agriculture College of Materials and Energy South China Agricultural University Wushan Road 483 Guangzhou 510630 People's Republic of China
| | - Changzhi Su
- Liaoyang Petrochemical Research Center Petrochemical Research Institute of PetroChina Huoju Road 7 Liaoyang 111003 People's Republic of China
| | - Junrong Wang
- Liaoyang Petrochemical Research Center Petrochemical Research Institute of PetroChina Huoju Road 7 Liaoyang 111003 People's Republic of China
| | - Yongnian Wang
- Liaoyang Petrochemical Research Center Petrochemical Research Institute of PetroChina Huoju Road 7 Liaoyang 111003 People's Republic of China
| | - Boping Liu
- Key Laboratory for Biobased Materials and Energy of Ministry of Education Guangdong Laboratory for Lingnan Modern Agriculture College of Materials and Energy South China Agricultural University Wushan Road 483 Guangzhou 510630 People's Republic of China
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Syntheses of Silylene-Bridged Thiophene-Fused Cyclopentadienyl ansa-Metallocene Complexes for Preparing High-Performance Supported Catalyst. Catalysts 2022. [DOI: 10.3390/catal12030283] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We synthesized a series of Me2Si-bridged ansa-zirconocene complexes coordinated by thiophene-fused cyclopentadienyl and fluorenyl ligands (Me2Si(2-R1-3-R2-4,5-Me2C7S)(2,7-R32C13H6))ZrMe2 (R1 = Me or H, R2 = H or Me, R3 = H, tBu, or Cl) for the subsequent preparation of supported catalysts. We determined that the fluorenyl ligand adopts an η3-binding mode in 9 (R1 = Me, R2 = H, R3 = H) by X-ray crystallography. Further, we synthesized a derivative 15 by substituting the fluorenyl ligand in 9 with a 2-methyl-4-(4-tert-butylphenyl)indenyl ligand, derivatives 20 and 23 by substituting the Me2Si bridge in 12 (R1 = Me, R2 = H, R3 = tBu) and 15 with a tBuO(CH2)6(Me)Si bridge, and the dinuclear congener 26 by connecting two complexes with a –(Me)Si(CH2)6Si(Me)– spacer. The silica-supported catalysts prepared using 12, 20, and 26 demonstrated up to two times higher productivity in ethylene/1-hexene copolymerization than that prepared with conventional (THI)ZrCl2 (21–26 vs. 12 kg-PE/g-(supported catalyst)), producing polymers with comparable molecular weight (Mw, 330–370 vs. 300 kDa), at a higher 1-hexene content (1.3 vs. 1.0 mol%) but a lower bulk density of polymer particles (0.35 vs. 0.42 g/mL).
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