聚二烯冠状体的可逆交叉链接在,块,和等级结构中使用Pt(0) -olefin协调 Pt(0) -olefin协调
Paul A Rupar1, Graeme Cambridge, Mitchell A Winnik
1School of Chemistry, University of Bristol, Bristol, United Kingdom, BS8 1TS.
Journal of the American Chemical Society
|October 5, 2011
概括
在块共聚合物微粒中催化聚索 (PI) 的交叉链接提供可逆结构稳定性和增强的成像对比度. 这种新的方法可以通过选择性地去除核心组件来创建复杂的空心纳米结构.
科学领域:
- 聚合物化学 聚合物化学
- 材料科学 材料科学 材料科学
- 纳米技术 纳米技术
背景情况:
- 之前的研究使用了水化来使聚二烯 (PI) 冠状体在聚铁二甲基 (PFS) 块共聚合物微粒中不可逆转的交叉链接.
- 众所周知,Karstedt的催化剂在有着西兰酸盐的存在下促进了水化反应.
研究的目的:
- 为了研究卡斯特德特催化剂单独诱导PI冠状病毒的交叉链接的潜力.
- 探索这种交叉链接机制的可逆性及其在纳米结构制造和成像中的应用.
主要方法:
- 在没有外部丝的情况下,用卡斯特德特催化剂处理圆柱形PI-b-PFS块共聚合物微粒.
- 通过使用2-bis(diphenylphosphino) ethane (dppe) 作为制剂来研究交叉链接可逆性.
- 交叉连接方法的应用,以增强传输电子显微镜 (TEM) 的对比度,并创建层次的纳米结构.
主要成果:
- 卡斯特德的催化剂单独诱导PI冠状的Pt(0) -olefin协调交叉链接,与水化不同.
- 由Pt(0) 诱导的交叉链接显著提高了PI-b-PFS状结构的稳定性.
- 在添加dppe后,交叉链接是可逆的,dppe将金隔离.
- 这一过程允许在PI和多二甲基素 (PDMS) 领域之间进行选择性的TEM对比增强.
- 一个分层的围巾形的漫画成功地被解构,在选择性地去除PFS-b-PDMS核心后留下一个空洞的结构.
结论:
- Pt(0) -olefin协调代表了聚二烯的新和可逆的交叉链路策略.
- 这种方法为稳定自组装纳米结构和创建先进材料提供了强大的工具.
- 调整交叉连接和脱离交叉连接的能力为复杂的纳米结构设计和操纵开辟了新的途径.
相关概念视频
Micelles
Micelle formation is an intricate process that hinges on the properties of amphiphilic or amphipathic molecules and the conditions of the system in which they are found. Amphiphilic molecules, which have both hydrophilic (water-attracting) and hydrophobic (water-repelling) parts, play a critical role in this process.In aqueous environments, these molecules arrange themselves such that their hydrophilic heads are turned towards the water phase, while their hydrophobic tails are oriented away...
Olefin 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...
Cationic 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,...
Olefin 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...
Olefin 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...
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...
Characteristics and Nomenclature of Copolymers
Copolymers are the products obtained from the polymerization of multiple monomer species. So, in a polymer chain itself, there can be multiple repeating units that come from different monomers. The process of synthesizing a polymer from different monomer species is called copolymerization. When two monomers are involved, the polymer is known as a bipolymer. Polymers with three and four monomers are termed terpolymers and quaterpolymers, respectively. Figure 1 depicts the copolymerization of...


