检索结果-南通市图书馆

Highly stereospecific polymerization of isoprene with homogeneous binary Ziegler-Natta catalysts based on NCN-pincer neodymium precursor

引用

Science China chemistry 2010年第8期53卷 1641-1645页

作者： liu dongtao1,2,cui dongmei1 & gao wei3 1state key laboratory of polymer physics and chemistry Changchun Institute of Applied chemistry,Chinese Academy of Sciences,Changchun 130022,China 2Graduate University of Chinese Academy of Sciences,Beijing 100039,China 3School of chemistry,Jilin University,Changchun 130012,China state key laboratory of polymer physics and chemistry Changchun Institute of Applied chemistry Chinese Academy of Sciences Changchun China Graduate University of Chinese Academy of Sciences Beijing China School of chemistry Jilin University Changchun China

The aryldiimine NCN-pincer stabilized neodymium dichloride combined with aluminum alkyls established a new type of homogeneous binary neutral Ziegler-Natta catalyst *** system exhibited high activity and high cis-1,4 selectivity for the polymerization of isoprene (Tp=20 °C,98.2%;Tp=-20 °C,> 99%).Such catalytic performances remained under a broad range of polymerization temperatures and monomer-to-neodymium ratios (from 500 to 8000),reaching high number-average molecular weight (Mn=1582 kg/mol) and relatively narrow molecular weight distribution (PDI=1.68),which was,however,influenced by the amount and bulkiness of aluminum *** investigation of the polymerization was performed,which showed the number-average molecular weight of the resultant polyisoprene had an almost linear correlation with the conversion,suggesting,in some degree,the polymerization with this catalytic system was controllable.

关键词： neodymium cis-1 4 selectivity NCN-pincer complex polyisoprene

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Self-assisted stereospecific polymerization of unmasked polar 4-methylthio-1-butene

引用

Science China chemistry 2019年第6期62卷 761-766页

作者： Yunjie Chai Chunji Wu dongtao liu Mingtao Run dongmei cui College of chemistry and Environmental Science Hebei University state key laboratory of polymer physics and chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences

Stereospecific polymerization of polar olefins has always been an attractive but challenging project because the Lewis basic polar groups of monomers are usually poisonous to the Lewis acidic metal centers of the catalysts. In this contribution,thiophene-fused cyclopentadienyl scandium complexes 1-3 were successfully synthesized. Combined with alkylaluminium and organoborate, these complexes showed extremely low activity and no selectivity for 1-hexene polymerization. Surprisingly,highly stereo-selective coordination polymerization of unprotected polar 4-methylthio-1-butene has been achieved in high activity for the first time under the same polymerization conditions. High-molecular-weight(M_n=110×10~3) and perfectly syndiotactic(rrrr>99%) poly(4-methylthio-1-butene)(P(MTB)) was afforded. Thus the methylthio-group-assisted mechanism that the unmasked methylthio group promoted the polymerization through σ-π chelation to the active scandium center together with the vinyl group was proposed. Moreover, the methylsulfonyl functionalized syndiotactic poly(1-butene) was also easily prepared by the oxidation of P(MTB). These results provided a new route for the synthesis of functionalized stereo-regular polyolefins.

关键词： self-assisted polymerization stereoselectivity polar α-olefin rare-earth metal catalyst functionalized poly(1-butene)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

SELECTIVE SYNTHESIS OF BIODEGRADABLE MATERIALS AND HIGH PERFORMANCE RUBBERS

SELECTIVE SYNTHESIS OF BIODEGRADABLE MATERIALS AND HIGH PERF...

引用

5th International Symposium on High-Tech polymer Materials

作者： Xinli liu Shihuili Baoli Wang wei gao dongmei cui state key laboratory of polymer physics and chemistry Changchun Institute of Applied chemistry Chinese Academy of Sciences Changchun 130022 China.

＜正＞Polylactides （PLAs） are the most promising biodegradable and biocompatible synthetic macromolecules,possessing versatile physical properties and having been widely used in medicine, pharmaceutics and tissue en...

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Precisely Controlled（co）polymerization of Diene and Styrene by Using rare-earth Metal Catalyst

Precisely Controlled（co）Polymerization of Diene and Styren...

引用

中国化学会第十届全国无机化学学术会议

作者： dongtao liu Bo liu Shihui Li Chunji Wu Fei Lin dongmei cui state key Lab of polymer physics and chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences

The precisely controlled polymerization of diene and styrene by using rare-earth metal catalysts will be reported. The pincer-type ligands stabilized rare-earth metal complexes catalyse the polymerizations of dienes to give highly cis-1,4 regulated rubber materials, while those attached by CGC-type of ligands provide 3,4-regularity for isoprene polymerization. The polymerization of styrene with extremely high syndioselectivity and catalytic activity have been achieved by using with almost the whole period of rare-earth metals based catalysts. The DFT simulation reveals that the ligand contributes to lower the LUMO energy of the active species, thus the activation energy is reduced and the catalytic activity increases. The electron donating side arm of the ligand, on the other hand, may increase the electron density of the active species, therefore, increase its durability to the polar monomers such as methoxyl and methysilyl styrenes, leading to, for the first time, highly active and syndioselective polymerization of these polar styrenes, to give functional polystyrenes. Based on this, the copolymerization of ethylene with polar styrenes are achieved. The position of the substituted polar group influence the coordination mode of the polar styrene to the active metal center, and further the reaction ratios of the polar and nonpolar styrenes, to afford different microstructure copolymer products.

关键词： rare earth catalyst coordination polymerization olefin stereoselectivity

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：