基于循环聚合物的凝
Ke Zhang1, Melissa A Lackey, Jun Cui
1Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003, United States.
Journal of the American Chemical Society
|March 1, 2011
概括
通过环膨胀元解聚合 (REMP) 和烯化学合成的新型循环聚合物网络表现出增强的特性. 与线性聚合物凝相比,这些循环聚-5-基-1-环氧 octene (PACOE) 凝具有更高的膨胀和机械强度.
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
- 有机化学 有机化学
背景情况:
- 传统的聚合物网络通常由线性聚合物链合成.
- 循环聚合物提供了独特的拓结构,在线性类似物中无法找到.
- 了解循环聚合物网络的结构属性关系对于先进的材料设计至关重要.
研究的目的:
- 为了合成和描述新型网络材料从循环多-5-基-1-循环 octene (PACOE).
- 与线性PACOE相比,研究使用循环PACOE作为前体对网络属性的影响.
- 探索初始聚合物度对这些新型循环聚合物凝的特性的影响.
主要方法:
- 通过环膨胀转化聚合 (REMP) 合成循环PACOE.
- 使用乙烯化学方法对PACOE进行交叉链接,以形成网络凝.
- 凝性质的表征包括凝分数 (GF),膨胀率 (Q) 和模量 (G) 在不同的初始聚合物度 (C(0)).
主要成果:
- 循环PACOE凝表现出具有拓交叉连接的独特结构单元.
- 与线性PACOE凝不同,循环PACOE凝显示GF,Q和G的同时增加,同时增加C(0).
- 循环PACOE凝显示出比线性PACOE凝具有更高的膨胀能力和更大的最大压力,在断裂时比线性PACOE凝更大,在更高的C(0) 时差异会放大.
结论:
- 新型网络材料可以有效地从循环PACOE中形成,使用乙烯化学.
- 使用循环聚合物前体导致与线性前体相比具有独特的网络特性.
- 这些循环聚合物凝为需要增强膨胀和机械强度的应用提供了有希望的候选人.
相关概念视频
01:03Step-Growth Polymerization: Overview
Step-growth or condensation polymerization is a stepwise reaction of bi or multifunctional monomers to form long-chain polymers. As all the monomers are reactive, most of the monomers are consumed at the early stages of the reaction to form small chains of reactive oligomers, which then combine to form long polymer chains in the late stages. Hence, the reaction has to proceed for a long time to achieve high molecular weight polymers.
Many natural and synthetic polymers are produced by...
Many natural and synthetic polymers are produced by...
01:20Types of Step-Growth Polymers: Polyesters
The introduction of polyesters has brought major development to the textile industry. The wrinkle-free behavior of polyester blends has eliminated the need for starching and ironing clothes.
Polyesters are commonly prepared from terephthalic acid and ethylene glycol; the crude product is known as poly(ethylene terephthalate) or PET. However, polyesters are synthesized industrially by transesterification of dimethyl terephthalate with ethylene glycol at 150 °C. The two reactants and the polymer...
Polyesters are commonly prepared from terephthalic acid and ethylene glycol; the crude product is known as poly(ethylene terephthalate) or PET. However, polyesters are synthesized industrially by transesterification of dimethyl terephthalate with ethylene glycol at 150 °C. The two reactants and the polymer...
02:34Polymers
The word polymer is derived from the Greek words “poly” which means “many” and “mer” which means “parts”. Polymers are long chains of molecules composed of repeating units of smaller molecules, known as monomers. They either occur naturally, such as DNA and proteins, or can be constructed synthetically, like plastics. They have varied structural characteristics, such as linear chains, branched chains, or complex networks, that contribute to the properties that they exhibit. Additionally,...
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,...
01:04Anionic 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.
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,...