Article
Chemistry, Physical
S. Olivia Gunther, Qingheng Lai, Todd Senecal, Rafael Huacuja, Sean Bremer, David M. Pearson, Jessica C. DeMott, Nattamai Bhuvanesh, Oleg Ozerov, Jerzy Klosin
Summary: By preparing and evaluating various carborane salts as activators, it was found that activators based on undecachloro carboranes led to highly active catalysts, while other activators were inactive under specific conditions. Polymer samples obtained from different catalysts showed similar performance, indicating that carborane anions do not influence catalyst kinetics.
Article
Chemistry, Multidisciplinary
Xiong Wang, Wenqian Kang, Lin Gao, Guangquan Li, Xuerong Chen, Yi Guo
Summary: In this study, nano TiO2 beads were used to modify the physical properties of POPs and achieved TiO2/POP supports with higher specific surface area and flowability, leading to improved catalytic activity. The prepared TiO2/POP catalyst showed higher ethylene polymerization activity compared to commercial metallocene catalyst, with the immobilized (n-BuCp)(2)ZrCl2/MAO@POP-7 catalyst exhibiting the highest productivity.
Article
Polymer Science
Laura Boggioni, Hitoshi Harakawa, Simona Losio, Kotohiro Nomura, Incoronata Tritto
Summary: The terpolymerizations of ethylene, norbornene, and 1-octene were studied using various aryloxo- or ketimide-modified half-titanocene catalysts in the presence of MAO cocatalysts. The ketimide-modified catalysts showed higher catalytic activities and yielded higher molecular weight terpolymers. This unique behavior is attributed to a lower propensity for beta-H elimination, resulting in terpolymers with high 1-octene contents and molar masses.
Article
Chemistry, Physical
Silvia Zanoni, Nikolaos Nikolopoulos, Alexandre Welle, Virginie Cirriez, Bert M. Weckhuysen
Summary: Commercial SiO2 modified with TiO2 shows a 35% enhancement in catalytic activity for metallocene-based ethylene polymerization catalysts. The effect of this modification on catalyst particle fragmentation during polymerization reactions was investigated using Focused-Ion Beam Scanning Electron Microscopy (FIB-SEM). The titanation of SiO2 resulted in an earlier and more efficient fracture of the support framework, leading to sustained macroporosity of the polymerized particles during the reaction.
Article
Polymer Science
Felicia Daniela Cannavacciuolo, Antonio Vittoria, Christian Ehm, Roberta Cipullo, Vincenzo Busico
Summary: This study explored the propensity of a catalyst to undergo coordinative chain transfer polymerization (CCTP) in propene polymerization, demonstrating that the catalyst is not prone to this process. A method to demonstrate the occurrence of CCTP in isotactic propene polymerization based on spectroscopic characterization of the sample was also proposed.
EUROPEAN POLYMER JOURNAL
(2021)
Article
Chemistry, Applied
Clinton Manianglung, Hye In Jeon, Young Soo Ko
Summary: The effect of incorporating amines and borane into supported metallocene catalyst systems was investigated. The presence of polyethyleneimine (PEI) increased the Zr content in the catalyst and yielded polyethylene with higher molecular weight. PEI also enhanced the comonomer response of supported metallocene catalysts. The immobilization of both PEI and borane significantly improved polymerization activity and promoted the formation of more active metallocene sites.
Article
Polymer Science
Li Zhou, Chong-Long Li, Run-Tan Gao, Shu-Ming Kang, Lei Xu, Xun-Hui Xu, Na Liu, Zong-Quan Wu
Summary: The facile synthesis of high optically active helical polymers from achiral monomers is still a challenge. Chiral Ni(II) catalysts were prepared to efficiently initiate living/controlled polymerization of allene monomers, exhibiting interesting regioselectivity and helix-sense selectivity. The resulting polyallenes showed high optical activity, solely determined by the chirality of the Ni(II) catalysts.
Article
Polymer Science
Zhikang Chen, Wuchao Zhao, Conglei Liu, Liuying Jiang, Gang Fu, Yuetao Zhang, Hongping Zhu
Summary: The use of easily synthesized phosphonium ylides as Lewis base in the Lewis pair polymerization of (meth)acrylates has been reported. Among the studied systems, the P-ylide-2/AlMe(BHT)(2) system is the best for living/controlled polymerizations.
Article
Biochemistry & Molecular Biology
Hyun-Ju Lee, Jun-Won Baek, Yeong-Hyun Seo, Hong-Cheol Lee, Sun-Mi Jeong, Junseong Lee, Chong-Gu Lee, Bun-Yeoul Lee
Summary: In this study, highly pure and soluble ammonium tetrakis(pentafluorophenyl)borates were prepared via acid-base reaction and used in the activation reactions of homogeneous olefin polymerization catalysts. These soluble and stable species were highly active in ethylene/1-octene copolymerization in aliphatic hydrocarbon solvents.
Article
Multidisciplinary Sciences
Wei Liu, Haisong Feng, Yusen Yang, Yiming Niu, Lei Wang, Pan Yin, Song Hong, Bingsen Zhang, Xin Zhang, Min Wei
Summary: The design and exploitation of high-performance catalysts for selective hydrogenation reactions is a significant challenge. In this study, the authors report a RuNi single atom alloy catalyst that exhibits exceptional activity and selectivity in the hydrogenation of 4-nitrostyrene.
NATURE COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Maximilian J. Werny, Kirsten B. Siebers, Nicolaas H. Friederichs, Coen Hendriksen, Florian Meirer, Bert M. Weckhuysen
Summary: The use of confocal fluorescence microscopy and advanced image processing allows for efficient evaluation of support fragmentation in olefin polymerization catalysts, revealing both intra- and interparticle heterogeneities in the catalyst particles. The observed heterogeneities are primarily attributed to the diverse support structures and metallocene distribution within the catalyst particles. Additionally, a significant number of catalyst particles exhibit limited support fragmentation at the onset of the reaction, potentially impacting the particle size distribution during the early stages of polymerization.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Polymer Science
Sung Moon Bae, Sun Mi Jeong, Jun Won Baek, Hyun Ju Lee, Hagjun Kim, Yeokwon Yoon, Sangchul Chung, Bun Yeoul Lee
Summary: The productivity of supported catalysts can be enhanced by using dinuclear metallocene complexes instead of the conventional mononuclear analogs, leading to reduced formation of large polymer particles.
EUROPEAN POLYMER JOURNAL
(2021)
Article
Chemistry, Physical
Silvia Zanoni, Alexandre Welle, Virginie Cirriez, Bert M. Weckhuysen
Summary: Chemical modification of titanium-doped SiO2 support improved the catalytic performance of zirconocene catalysts, resulting in a 35% increase in ethylene polymerization yields. The improved catalyst activity was attributed to the presence of Ti-based active sites and higher Lewis acidity in the titanated supported-MAO. The Ti active species were generated by reduction of Ti/SiO2 support with the MAO co-catalysts, introducing oxygen vacancies and Ti3+ species.
Article
Polymer Science
Artem A. Antonov, Konstantin P. Bryliakov
Summary: This review highlights the progress in transition metal catalyzed ethylene polymerization to UHMWPE, focusing on the catalytic activities of different post-metallocene systems, polymer properties, and experimental conditions. The review covers the time span of 2010 to present with a total of 161 references.
EUROPEAN POLYMER JOURNAL
(2021)
Article
Chemistry, Multidisciplinary
Xue Zhao, Manussada Ratanasak, Jun-ya Hasegawa, Kazumasa Kon, Kazuaki Ishihara
Summary: This study developed magnesium(ii) and sodium(i) complexes derived from BHT-H and PBTP-H-2 as catalysts for the transesterification of MA and MMA. The Mg(PBTP) and Na-2(PBTP) catalysts were found to be 41 and 81 times more effective than Mg(BHT)(2) and Na(BHT), respectively. These catalysts showed high efficiency across a range of alcohols.