ルイス酸によって促進された2クロロチオフェンの鎖成長ポリメリゼーション
Baltasar Bonillo1, Timothy M Swager
1Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Journal of the American Chemical Society
|November 10, 2012
まとめ
ルイス酸は,2-クロロアルキレン・ダイオキシチオフェンのカチオン鎖成長ポリメリゼーションを可能にし,高分子量結合ポリマーを生成します. この生体ポリメリゼーションプロセスは,新しいブロックコポリマーの合成を可能にします.
科学分野:
- ポリマー化学のポリマー化学について
- オーガニック・シンセシス オーガニック・シンセシス
- マテリアルサイエンス 材料科学
背景:
- 結合ポリマーは,有機電子工学にとって極めて重要です.
- ポリメリゼーションの制御は,望ましいポリマー特性を達成するための鍵です.
- 2-クロロアルキルレン二酸化チオフェンは,機能性ポリマーのモノマーである.
研究 の 目的:
- 2-クロロアルキレンダイオキシチオフェンのルイス酸触媒ポリメリゼーションを調査する.
- ポリメリゼーションメカニズムを解明するために.
- 高分子量結合ポリマーとブロックコポリマーを合成するために.
主な方法:
- ルイス酸を用いたカチオン鎖成長ポリメリゼーション.
- ポリメリゼーションメカニズムを確認するためのエンドキャピング反応.
- 分子重量とモノマー変換のモニタリング.
主要な成果:
- 高分子量結合ポリマーが成功して合成されました.
- ポリメリゼーションは,cationic chain-growthメカニズムを介して進行する.
- ポリメリゼーションの"生きている"性質が実証され,ブロックコポリマー合成を可能にしました.
結論:
- ルイス酸は,2-クロロアルキレン・ダイオキシチオフェンの生カチオンのポリメリゼーションを効果的に触媒化する.
- この方法は,明確に定義された結合ポリマーとブロックコポリマーへの経路を提供します.
- この発見は,新しい機能的なポリマー材料の道を開く.
関連する概念動画
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,...
01:10Radical Chain-Growth Polymerization: Overview
Chain-growth or addition polymerization is successive addition reactions of monomers with a polymer chain. In radical chain-growth polymerization, the reaction proceeds via a free-radical intermediate. The free radical is formed from radical initiators, which spontaneously generate free radicals by homolytic fission. Organic peroxides (such as dibenzoyl peroxide, as shown in Figure 1) or azo compounds are popular radical initiators. A low concentration ratio of radical initiator to monomer is...
01:17Ziegler–Natta Chain-Growth Polymerization: Overview
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta catalyst, high molecular...
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.
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...
01:09Radical Chain-Growth Polymerization: Mechanism
The radical chain-growth polymerization mechanism consists of three steps: initiation, propagation, and termination of polymerization. The polymerization initiates when a free radical generated from the radical initiator adds to the unsaturated bond in the monomer. The unpaired electron of the free radical and one π electron in the unsaturated bond creates a σ bond between the free radical and the monomer. As a result, the other π electron in the unsaturated bond converts this species into the...