Search

Your search keyword '"Sun, Wen-Hua"' showing total 1,510 results
Start Over Author "Sun, Wen-Hua"
1,510 results on '"Sun, Wen-Hua"'

22. Intensive Cycloalkyl-Fused Pyridines for Aminopyridyl–Zinc–Heteroimidazoles Achieving High Efficiency toward the Ring-Opening Polymerization of Lactides.

Author

Wang, Yun, Zhang, Wenjuan, Zhu, Pengjiang, You, Wei, Xue, Xiaopan, Wang, Rui, Ma, Yanping, and Sun, Wen-Hua

Subjects
RING-opening polymerization, LACTIDES, ELEMENTAL analysis, POLYMERS, CATALYSTS, ZINC catalysts
Abstract

The model precatalyst sp3- and sp2-N dinitrogen-coordinated zinc–heteroimidazole has been used as an efficient catalyst for the ring-opening polymerization of cyclic esters. Subsequent to our exceptional active 5,6,7-trihydroquinolin-8-amine-zinc catalysts for the ring-opening polymerization (ROP) of ε-caprolactone, various pyridine-fused cycloalkanones (ring size from five to eight) are developed for the correspondent fused amine–pyridine derivatives and their zinc–heteroimidazole chloride complexes Zn1–Zn8 (LZnCl2) bearing N-diphenylphosphinoethyl pendants. Activated with two equivalents of LiN(SiMe3)2, the title zinc complexes efficiently promote the ROP of L-lactide (L-LA) in situ; among them, Zn4/2Li(NSiMe3)2 catalyzed 500 equivalent L-LA at 80 °C with 92% conversion in 5 min (TOF: 5520 h−1). Under the same conditions, the catalytic efficiency for the ROP of rac-LA by Zn1–Zn8/2Li(NSiMe3)2 was slightly lower than that for L-LA (highest TOF: 4440 h−1). In both cases, cyclooctyl-fused pyridyl–zinc complexes exhibited higher activity than others, while the cycloheptyl-fused zinc complexes showed the lowest activity. The microstructure analysis of the polymers showed they possessed a linear structure capped with CH3O as major and cyclic structure as minor. In this work, all the ligands and zinc complexes were well characterized by 1H/13C/31P NMR, FT-IR spectroscopy as well as elemental analysis. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

34. Thermostability promotion of α-diimine nickel precatalysts tailored with 2,6-bis(bis(4-fluorophenyl)methyl)-3,4,5-trimethoxyaniline for PE elastomer synthesis.

Author

Hu, Zexu, Ren, Geng, Mahmood, Qaiser, Yu, Zhixin, Wang, Yizhou, Tahir, Kainat Fatima, Zou, Song, Liang, Tongling, and Sun, Wen-Hua

Subjects
THERMOPLASTIC elastomers, ELASTICITY, STERIC hindrance, NICKEL catalysts, NICKEL, POLYURETHANE elastomers, ELASTOMERS
Abstract

The influence of axial steric hindrance in α-diimine nickel catalysts on ethylene polymerization is paramount for enhancing the catalytic performance especially in terms of thermal stability and polymer molecular weights. In this study, a set of five nonsymmetrical 1,2-bis(arylimino)acenaphthene–nickel complexes, incorporating 2,6-bis(bis(4-fluorophenyl)methyl)-3,4,5-trimethoxyaniline and 2,4,6-trialkylaniline moieties, was prepared to tailor the catalytic attributes for ethylene polymerization. In-depth studies on the polymerization of ethylene, using two different cocatalysts and different reaction conditions, revealed exceptional catalytic activities for these precatalysts with activity levels as high as 20.3 × 106 g mol−1 h−1 at 30 °C and high molecular weights of the obtained polyethylene with adjustable branching degrees and distributions. Reactions at elevated temperatures validated the enhanced thermal stability of Ni-Me2 precatalysts, displaying a noteworthy activity of 1.4 × 106 g mol−1 h−1 at 100 °C. Polyethylene derived from more sterically hindered nickel complexes exhibited relatively higher molecular weights and branching degrees compared to less hindered analogues. This trend was consistent across mechanical and elastic properties, which ranged from 6.1 MPa to 10.6 MPa and 26% to 49%, respectively. Moreover, the manipulation of branching degree by increasing the reaction temperature led to an elastic recovery of up to 63%, indicating potential formation of thermoplastic polyethylene elastomers. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

35. Effects of Taurine on Broiler Aortic Endothelial Cells Activity and Antioxidant Ability Impired by Heat Stress In Vitro

Author

Fang, Da-lin, Lin, Shumei, Wang, Zhenyong, Gao, Wei-fan, Cui, Yiqing, Sun, Rui-yuan, Sun, Wen-hua, Huang, Fan, Lv, Qiufeng, LAMBRIS, JOHN D., Editorial Board Member, REZAEI, NIMA, Editorial Board Member, Hu, Jianmin, editor, Piao, Fengyuan, editor, Schaffer, Stephen W., editor, El Idrissi, Abdeslem, editor, and Wu, Jang-Yen, editor

Published
2019
Full Text
View/download PDF

50. Predicting the catalytic activities of transition metal (Cr, Fe, Co, Ni) complexes towards ethylene polymerization by machine learning.

Author

Meraz, Md Mostakim, Yang, Wenhong, Yang, Weisheng, and Sun, Wen‐Hua

Subjects
CATALYTIC activity, POLYMERIZATION, MACHINE learning, TRANSITION metals, NICKEL catalysts, TRANSITION metal complexes, ETHYLENE
Abstract

The study aims to execute machine learning (ML) method for building an intelligent prediction system for catalytic activities of a relatively big dataset of 1056 transition metal complex precatalysts in ethylene polymerization. Among 14 different algorithms, the CatBoost ensemble model provides the best prediction with the correlation coefficient (R2) values of 0.999 for training set and 0.834 for external test set. The interpretation of the obtained model indicates that the catalytic activity is highly correlated with number of atom, conjugated degree in the ligand framework, and charge distributions. Correspondingly, 10 novel complexes are designed and predicted with higher catalytic activities. This work shows the potential application of the ML method as a high‐precision tool for designing advanced catalysts for ethylene polymerization. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results