切换和扩展一个[c2]daisy链二元聚合物
Paul G Clark1, Michael W Day, Robert H Grubbs
1The Arnold 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
|September 5, 2009
概括
研究人员通过催化合成了一种新的链二聚体. 这种机械互锁的分子可以在形状之间切换,并纳入聚合物,展示可调节的材料特性.
科学领域:
- 超分子化学 超分子化学
- 聚合物科学 聚合物科学
- 有机合成 有机合成
背景情况:
- 机械互锁分子 (MIM) 由于其非共价键,具有独特的特性.
- 控制MIM的结构状态对于开发先进材料至关重要.
- 将MIM集成到聚合物架构中,可以创建功能性宏分子.
研究的目的:
- 通过催化环闭氨酸转化合成一种新的链二聚体.
- 为了研究合成的二分体的构造性切换行为.
- 将二元体纳入线性聚合物链并研究由此产生的材料特性.
主要方法:
- 催化环闭性烯酸甲解质用于二元合成.
- 单晶X射线衍射用于结构确认.
- 酸处理用于形状切换.
- 聚合物合并的阿尔基因-亚酸点击化学.
- 凝透色谱和多角度激光光散射 (GPC-MALLS) 用于聚合物表征.
主要成果:
- 通过X射线衍射证实[c2]百合链二元体的成功合成.
- 用KOH和HPF可逆切换二元体的构造.
- 通过点击化学,以化物功能化的二元体被纳入线性聚合物中.
- 含有22个二极体的聚合物表现出一个旋转半径 (R(g)) 14.8 nm.
- 乙化导致了固体阻碍,使聚合物的R (g) 增加了48%至21.4nm.
结论:
- 这项研究表明,可以轻松合成可切换的花链二元体.
- 通过点击化学,二分体可以有效地集成到聚合物骨干中.
- 嵌入的二元体的构造状态会影响整体聚合物尺寸,为可调节的聚合物架构提供了一条路径.
更多相关视频
相关概念视频
00:57Cationic Chain-Growth Polymerization: Mechanism
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the generated carbocation,...
01:04Anionic Chain-Growth Polymerization: Mechanism
The mechanism for anionic chain-growth polymerization involves initiation, propagation, and termination steps. In the initiation step, a nucleophilic anion, such as butyl lithium, initiates the polymerization process by attacking the π bond of the vinylic monomer. As a result, a carbanion, stabilized by the electron‐withdrawing group, is generated. The resulting carbanion acts as a Michael donor in the propagation step and attacks the second vinylic monomer, which acts as a Michael acceptor.
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
01:20Anionic Chain-Growth Polymerization: Overview
The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
01:17Radical Chain-Growth Polymerization: Chain Branching
The skeletal structure of polymers synthesized via radical polymerization is always branched. For example, the polymerization of ethylene by radical polymerization results in a low-density grade of polyethylene with a heavily branched skeletal structure. Here, the radical site abstracts hydrogen from the growing chain, and the radical site shifts from the end (a primary carbon center) to anywhere within the growing chain (a secondary carbon center). Consequently, the part of the chain from the...
01:29Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.