通过使用转化催化剂的环开通转化聚合,合成高,综合性聚合物
Lauren E Rosebrugh1, Vanessa M Marx, Benjamin K Keitz
1Arnold and Mabel Beckman Laboratory of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|June 21, 2013
概括
催化剂使环开放型元解聚合能够产生高和高战术性聚合物. 这一突破为聚合物微结构提供了精确的控制,在许多情况下达到95%以上的CIS含量和战术性.
科学领域:
- 聚合物化学 聚合物化学
- 有机金属化学 有机金属化学
- 材料科学 材料科学 材料科学
背景情况:
- 环开元化聚合 (ROMP) 是一种强大的聚合物合成技术.
- 在ROMP中同时实现高 cis选择性和战术性一直是一个重大挑战.
- 催化剂在各种聚合反应中表现有前途.
研究的目的:
- 举报第一个以为媒介的ROMP产生的高度cis,高度战术性聚合物的例子.
- 研究单体结构对cis含量和战术性的影响.
- 为了探索由化纯单体衍生的聚合物的微观结构.
主要方法:
- 使用以为基础的催化剂进行环开放型转化聚合.
- 从各种诺伯烯衍生物合成聚合物.
- 使用技术分析聚合物微结构,以确定cis含量和战术性 (例如NMR光谱学).
主要成果:
- 成功实现了以为媒介的ROMP,产生含有高 cis 含量 (在某些情况下高于95%) 和高战术性 (>95%) 的聚合物.
- 证明cis含量取决于特定的单体结构.
- 聚合了纯的2,3-dicarboalkoxynorbornadiene,从而形成了一个协同的微观结构.
结论:
- 催化剂有效地通过ROMP合成高度cis,高度战术性的聚合物.
- 开发的方法为精确控制聚合物微观结构提供了一条新途径.
- 这种进步为创建具有定制性质的先进材料提供了可能性.
相关概念视频
01:13Olefin Metathesis Polymerization: Overview
Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
00:53Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
Acyclic diene metathesis polymerization or ADMET polymerization involves cross-metathesis of terminal dienes, such as 1,8-nonadiene, to give linear unsaturated polymer and ethylene. As ADMET is a reversible process, the formed ethylene gas must be removed from the reaction mixture to complete the polymerization process.
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
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01:17Ziegler–Natta Chain-Growth Polymerization: Overview
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta catalyst, high molecular...
02:26Base-Catalyzed Ring-Opening of Epoxides
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02:24Acid-Catalyzed Ring-Opening of Epoxides
Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...