在极性溶剂中对超高分子量聚乙烯进行控制的聚合
Philip Kenyon1, Melissa Wörner1, Stefan Mecking1
1Chemical Materials Science, Department of Chemistry , University of Konstanz , Universitätsstrasse 10 , 78457 Konstanz , Germany.
Journal of the American Chemical Society
|May 18, 2018
概括
新的复合物可以控制高分子量聚乙烯 (UHMWPE) 的合成. 这些催化剂具有活性聚合特性,即使在高温下也能产生高度线性UHMWPE.
科学领域:
- 有机金属化学
- 聚合物科学
- 催化剂
背景情况:
- 在协调化学中,2,4,8-triarylnaphthylamine连接体至关重要.
- 复合物被广泛用于聚合反应中的催化剂.
研究的目的:
- 通过2,4,8-triarylnaphthylamine连接物合成新的复合物.
- 研究这些复合物在乙烯聚合中的催化活性.
- 制造具有受控性能的超高分子量聚乙烯 (UHMWPE).
主要方法:
- 通过选择性化,玻利化和合合成8-烯胺.
- 一次合成的新复合物.
- 使用在极性有机溶剂中合成的复合物的乙烯聚合.
主要成果:
- 成功合成了新的复合物 (4-Py和5-Py).
- 具有可控分子量 (M w/M n = 1.2) 的活体聚合特性.
- 在60°C时形成具有高线性超高分子量聚乙烯 (UHMWPE).
结论:
- 新型复合物是生产UHMWPE的有效催化剂.
- 5-Py复合体对β-H消除的倾向较低,使其具有高线性.
- 控制的聚合条件导致高分子量和线性聚乙烯结构.
相关概念视频
Molecular Shape and Polarity
76.0K
Dipole Moment of a Molecule
76.0K
Solvents
71.3K
A solvent is a substance, most often a liquid, that can dissolve other substances. Here, the substance being dissolved is called a solute. When a solvent and a solute combine, they form a solution - a homogenous mixture of both the solvent and the solute. Water is a universal biological solvent. Its polar structure allows it to dissolve many other polar compounds. The ability of water to dissolve is governed by a balance between water molecules binding to each other and binding to the solute.
A...
A...
71.3K
Polymers: Defining Molecular Weight
3.9K
Unlike small molecules with definite molecular weights, polymers are a mixture of individual polymer chains of varying lengths, each with a unique molecular weight. So, the molecular weight of a polymer is expressed as an average value based on the average size of the polymer chains. The two most common forms of averages used for polymers are the number average molecular weight and weight average molecular weight.
The number average molecular weight (Mn) is the summation of the number...
The number average molecular weight (Mn) is the summation of the number...
3.9K
Polymers: Molecular Weight Distribution
4.9K
For any given polymer, the weight average molecular weight (Mw) is higher than, if not equal to, the number average molecular weight (Mn). The only situation in which the weight average molecular weight and the number average molecular weight are equal is when a polymer consists only of chains with equal molecular weight. However, this never happens in a synthetic polymer, since it is difficult to control the polymerization process up to a molecular level with accuracy to a hundred percent.
4.9K
Molecular Weight of Step-Growth Polymers
2.9K
Step growth polymerization involves bi or multifunctional monomers. Bifunctional monomers react to form linear step growth polymers, whereas multifunctional monomers react to form non-linear or branched polymers.
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
As the step-growth polymerization involves step-wise condensation of monomers, the molecular weight also builds up eventually. Consequently, high molecular weight polymers are obtained at the late stages of the polymerization, where 99% of monomers have been consumed.
The extent of the...
2.9K
Anticoagulant Drugs: Low-Molecular-Weight Heparins
2.0K
Hemostasis is a crucial process that prevents excessive blood loss from damaged blood vessels. It involves various mechanisms such as vasoconstriction, platelet adhesion and activation, and fibrin formation. The importance of each mechanism depends on the type of vessel injury. In contrast, thrombosis is the abnormal formation of a blood clot within the blood vessels, leading to potential complications if the clot obstructs blood flow. Thrombosis can be caused by increased coagulability of the...
2.0K


