scholarly journals Studies on chain shuttling polymerization reaction of nonbridged half-titanocene and bis(phenoxy-imine) Zr binary catalyst system

2019 ◽  
Vol 6 (4) ◽  
pp. 182007 ◽  
Author(s):  
Qinwen Xu ◽  
Rong Gao ◽  
Dongbing Liu
Keyword(s):  
Block Copolymers ◽  
Catalyst System ◽  
Polymer Chains ◽  
New Combination ◽  
Polymerization Reaction ◽  
Block Polymer ◽  
A Chain ◽  
Binary Catalyst ◽  
Chain Shuttling Polymerization ◽  
First Time

In this contribution, olefin block copolymers were produced via chain shuttling polymerization (CSP), using a new combination of catalysts and a chain shuttling agent (CSA) diethylzinc (ZnEt 2 ). The binary catalyst system included nonbridged half-titanocene catalyst, Cp*TiCl 2 (O-2,6- i Pr 2 C 6 H 3 ) (Cat A ) and bis(phenoxy-imine) zirconium, { η 2 -1-[C(H)=NC 6 H 11 ]-2-O-3- t Bu-C 6 H 3 } 2 ZrCl 2 (Cat B ), as well as co-catalyst methylaluminoxane (MAO). In contrast to dual-catalyst system in the absence of CSA, the blocky structure was obtained in the presence of CSA and rationalized from rheological studies. The binary catalyst system could cause the CSP reaction to occur in the presence of CSA ZnEt 2 , which yielded broad distribution ethylene/1-octene copolymers ( M w / M n : 35.86) containing block polymer chains with high M w . The presented dual-catalytic system was applied for the first time in CSP and has a potential to be extended to produce a library of olefin block copolymers that can be used as advanced additives for thermoplastics.

scholarly journals Ethylene-co-norbornene Copolymerization Using a Dual Catalyst System in the Presence of a Chain Transfer Agent

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 554 ◽  
Author(s):  
Laura Boggioni ◽  
Diego Sidari ◽  
Simona Losio ◽  
Udo Stehling ◽  
Finizia Auriemma ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Chain Transfer ◽  
Catalyst System ◽  
Polymer Chains ◽  
Chain Transfer Agent ◽  
Reactivity Ratios ◽  
A Chain ◽  
Reactor Blend ◽  
The Ideal

Ethylene-co-norbornene copolymers were synthesized by a dual catalyst system at three concentrations of norbornene in the feed and variable amounts of ZnEt2, as a possible chain transfer agent. The dual catalyst system consists of two ansa-metallocenes, isopropyliden(η5-cyclopentadienyl)(η5-indenyl)zirconium dichloride (1) and isopropyliden(η5-3-methylcyclopentadienyl)(η5-fluorenyl)zirconium dichloride (2), activated with dimethylanilinium tetrakis(pentafluorophenyl)borate, in presence of TIBA. Values of norbornene content, molecular mass, glass transition temperature, and reactivity ratios r11 and r21 of copolymers prepared in the presence of 1+2 are intermediate between those of reference copolymers. The study of tensile and elastic properties of ethylene-co-norbornene copolymers (poly(E-co-N)s) gave evidence that copolymers were obtained in part through transfer of polymer chains between different transition metal sites. Mechanical properties are clearly different from those expected from a blend of the parent samples and reveal that copolymers obtained in the presence of 1+2 and ZnEt2 consist of a reactor blend of segmented chains produced by exchange from 2 to 1 and 1 to 2 acting as the ideal compatibilizer of chains produced by the chain transfer from 1 to 1, and from 2 to 2.

Redox-active polymer-nanoparticle hybrid materials

2000 ◽  
Vol 72 (1-2) ◽  
pp. 67-72 ◽  
Author(s):  
Keith J. Watson ◽  
Jin Zhu ◽  
SonBinh T. Nguyen ◽  
Chad A. Mirkin
Keyword(s):  
Gold Nanoparticles ◽  
Block Copolymers ◽  
Hybrid Materials ◽  
Ring Opening ◽  
Gel Permeation Chromatography ◽  
Polymer Chains ◽  
Electrochemical Studies ◽  
Redox Active ◽  
Gel Permeation ◽  
Current Rectification

Ring-opening metathesis polymerization was used to modify organic soluble gold nanoparticles with redox-active polymers. A gel-permeation chromatography study revealed that each nanoparticle is modified with approximately 11 polymer chains. Electrochemical studies of nanoparticles modified with block copolymers of two different redox-active groups revealed that each monomer is electrochemically accessible, while no current rectification was observed.

Six new species of Tonsilla Wang & Yin, 1992 (Araneae: Agelenidae) from southern China, with the first description of the male of T. yanlingensis (Zhang, Yin & Kim, 2000)

Zootaxa ◽  
2022 ◽  
Vol 5091 (2) ◽  
pp. 357-372
Author(s):  
MENG ZHANG ◽  
MUHAMMAD IRFAN ◽  
LU-YU WANG ◽  
ZHI-SHENG ZHANG
Keyword(s):  
New Species ◽  
Related Species ◽  
Southern China ◽  
New Combination ◽  
Distribution Map ◽  
Closely Related Species ◽  
First Time

Six new species of the spider genus Tonsilla Wang & Yin, 1992 are described from southern China: T. jinyunensis sp. nov. (♂♀) from Chongqing, T. jiugongensis sp. nov. (♂♀) from Hubei, T. subtruculenta sp. nov. (♂♀), T. rutunda sp. nov. (♂♀) and T. yueliangensis sp. nov. (♂) from Guizhou and T. subrostrum sp. nov. (♂♀) from Hunan. In addition, T. yanlingensis (Zhang, Yin & Kim, 2000) is redescribed and its male is described here for the first time. Tonsilla subyanlingensis Liu & Xu, 2020 is transferred to Draconarius Ovtchinnikov, 1999, hence the new combination Draconarius subyanlingensis (Liu & Xu, 2020) comb. nov. is established. The female of T. subyanlingensis Liu & Xu, 2020 should be treated as T. yanlingensis (Zhang, Yin & Kim, 2000). Detailed descriptions, photographs of copulatory organs and somatic features, a distribution map and comparisons with closely related species are presented.  

Ascospore sculpturing and generic concepts in the Testudinaceae (syn. Zopfiaceae)

1979 ◽  
Vol 57 (2) ◽  
pp. 91-99 ◽  
Author(s):  
D. L. Hawksworth
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
New Combination ◽  
The Family ◽  
First Time ◽  
Scanning Electron

Generic concepts in the Testudinaceae (Ascomycotina, Loculoascomycetes) are reviewed with particular emphasis on the sculpturing of the ascospores which has been examined by scanning electron microscopy (SEM) for the first time. A key to the nine genera accepted in the family is provided of which two are described as new: Ulospora for U. bilgramii comb.nov. (= Zopfia bilgramii D. Hawksw. et al.), the ascospores of which have three to six deep fissures in each cell, and Zopfiofoveola for Z. punctata comb.nov. (= Zopfia punctata D. Hawksw. & C. Booth), with distinctly and regularly foveolate ascospores. One further new combination is made: Rechingeriella boudieri comb.nov. (= Zopfia boudieri Arnaud). The positions of three additional genera referred to the family by earlier authors but which are excluded from it here are also briefly discussed.

Flabelloporina, a new genus in the Porinaceae (Ascomycota, Ostropales), with the first record of F. squamulifera from Brazil

Phytotaxa ◽  
2018 ◽  
Vol 358 (1) ◽  
pp. 67 ◽  
Author(s):  
PRISCYLLA NAYARA BEZERRA SOBREIRA ◽  
MARCELA EUGENIA DA SILVA CÁCERES ◽  
LEONOR COSTA MAIA ◽  
ROBERT LÜCKING
Keyword(s):  
Costa Rica ◽  
New Genus ◽  
First Record ◽  
Lichenized Fungi ◽  
New Combination ◽  
The Family ◽  
First Time

A new genus of lichenized fungi of the family Porinaceae is described, known from Costa Rica and Brazil. Flabelloporina Sobreira, M. Cáceres & Lücking is a thus far monospecific genus with an isolated position of its only species in the family, morphologically different from all other genera in Porinaceae. The genus is characterized by the production of numerous, flabelliform squamules on the surface of the thallus, together with black perithecia and transversally septate ascospores (with three septa in the only species). The new combination Flabelloporina squamulifera (Breuss, Lücking & Navarro) Sobreira, M. Cáceres & Lücking is proposed, based on Porina squamulifera Breuss, Lücking & Navarro, and the species is for the first time reported from Brazil.

scholarly journals Effects of Various Mixed Metal Chlorides- AlCl3 in TiCl4/MgCl2/THF Catalytic System on Ethylene Polymerization

2015 ◽  
Vol 14 (2) ◽  
pp. 12
Author(s):  
Nittaya Sudsong ◽  
Wanna Phiwkliang ◽  
Bunjerd Jongsomjit ◽  
Piyasan Praserthdam
Keyword(s):  
Catalytic System ◽  
Ethylene Polymerization ◽  
Catalyst System ◽  
Polymerization Reaction ◽  
Molar Ratio ◽  
Metal Chlorides ◽  
Mixed Metal ◽  
Icp Analysis ◽  
Co Addition

In this research, the modification of TiCl4/MgCl2/THF catalyst system with various metal chlorides was investigated on ethylene polymerization. Experimentally, metal chlorides (CaCl2, FeCl2 and ZnCl2) were simultaneously introduced different with TiCl4/MgCl2/THF catalyst. ICP analysis was used to determine the total amount of each metal in the catalyst. For polymerization reaction, TEA was used as cocatalyst and hexane was used as a medium solvent. The Al/Ti molar ratio was 140. The activity result of Ca-Al, Zn-Al and Fe-Al was 979, 1009 and 1476 kgPE/molTi.h, respectively. The coaddition of AlCl3 and FeCl2 in TiCl4/MgCl2/THF catalyst system exhibited the highest activity. It suggested that the co-addition of AlCl3 and FeCl2 has higher electronegativity (EN) and the radius of Fe2+ is closer to Mg2+ resulting in an increased efficiency of the THF removal. This result led to improve the catalyst performance.

On the taxonomy and biology of the clearwing moth Aegeria montis (Lepidoptera, Sesiidae)

Zootaxa ◽  
2018 ◽  
Vol 4369 (3) ◽  
pp. 443
Author(s):  
NAOKI YATA ◽  
OLEG G. GORBUNOV ◽  
YUTAKA ARITA ◽  
YOSHICHIKA AOKI
Keyword(s):  
Host Plant ◽  
Type Species ◽  
Systematic Position ◽  
New Combination ◽  
Clearwing Moth ◽  
First Time ◽  
Subjective Synonym

The systematic position of Aegeria montis Leech, 1889 and Zhuosesia zhuoxiana Yang, 1977 is discussed. Having studied newly collected material, we transfer A. montis to the genus Chamaesphecia Spuler, 1910, subgenus Chamaesphecia s. str. The male of this species and its genitalia are illustrated for the first time. The host-plant of its larvae is assumed to be a species of Euphorbia (Euphorbiaceae).        Zhuosesia Yang, 1977, syn. nov., is shown to be a junior subjective synonym of Chamaesphecia Spuler, 1910 with the new combination of its type species, Chamaesphecia zhuoxiana (Yang, 1977), comb. nov. 

scholarly journals Correction: A binary catalyst system of a cationic Ru–CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide

2017 ◽  
Vol 53 (2) ◽  
pp. 459-459
Author(s):  
Chee Koon Ng ◽  
Jie Wu ◽  
T. S. Andy Hor ◽  
He-Kuan Luo
Keyword(s):  
Carbon Dioxide ◽  
Alkali Metal ◽  
Metal Salt ◽  
Alkali Metal Salt ◽  
Catalyst System ◽  
Pincer Complex ◽  
Binary Catalyst

Correction for ‘A binary catalyst system of a cationic Ru–CNC pincer complex with an alkali metal salt for selective hydroboration of carbon dioxide’ by Chee Koon Ng et al., Chem. Commun., 2016, 52, 11842–11845.

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