在动态乙烯光聚合物中通过化学放大激活转化
Walter Alabiso1, Bernhard Sölle1, David Reisinger1
1Polymer Competence Center Leoben GmbH, Sauraugasse 1, A-8700, Leoben, Austria.
Angewandte Chemie (International ed. in English)
|September 7, 2023
概括
这项研究引入了动态聚合物网络的化学放大,使UV控制的键交换反应成为可能. 这一创新增强了对聚合物网络属性的控制,平衡了强度和可变性.
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
- 摄影化学的使用.
背景情况:
- 化学放大是光电阻的关键,通过光化学事件改变聚合物溶解度.
- 动态聚合物网络提供可调节的特性,但在平衡爬行阻力和回流能力方面面临挑战.
研究的目的:
- 为动态聚合物网络适应化学放大.
- 通过使用紫外线照射来实现对债券交换反应的时空控制.
主要方法:
- 使用光化学生成的酸,在乙烯基单体上切割三丁基碳酸保护基.
- 使用释放的酸来催化热激活转化以进行债券交换.
- 将这个系统集成到一个直角固化 (450 nm) 醇-点击光聚合物中.
主要成果:
- 在紫外线下成功释放催化剂和功能组.
- 在光聚合物网络中实现了对债券交换反应的时空控制.
- 展示了一种方法,以解决动态聚合物网络中的爬行阻力和回流能力之间的权衡.
结论:
- 开发的方法可以精确控制动态聚合物网络的修改.
- 这一策略为设计具有定制机械性能的先进材料提供了一条途径.
- 化学放大为设计响应和适应性的聚合物系统提供了强大的工具.
相关概念视频
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.9K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
1.9K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
2.4K
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
2.4K
01:13Olefin Metathesis Polymerization: Overview
2.2K
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...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists...
2.2K
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
2.1K
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
2.1K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.0K
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
2.0K
00:53Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
1.9K
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...
1.9K