分子ブラシの合成は"移植"法による:ATRPとクリック反応の組み合わせ
Haifeng Gao1, Krzysztof Matyjaszewski
1Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
Journal of the American Chemical Society
|May 1, 2007
まとめ
研究者は,原子移転ラジカルポリメリゼーション (ATRP) とクリック化学を使用して,密度の高い分子ブラシを合成しました. 彼らは,サイドチェーン特性と反応条件を最適化することで,高度なポリマーアーキテクチャを作成し,高い接ぎ木密度を達成しました.
科学分野:
- ポリマー化学のポリマー化学について
- マテリアルサイエンス 材料科学
- マクロ分子工学 マクロ分子工学
背景:
- 分子ブラシは,ボトルブラシマクロ分子とも呼ばれ,密度に接ぎ木されたサイドチェーンを持つポリマーです.
- これらの複雑なアーキテクチャはユニークな特性を提供しますが,制御された合成方法が必要です.
- "接ぎ木"のアプローチは,明確に定義されたポリマー構造の作成を可能にします.
研究 の 目的:
- ATRPとクリック化学の組み合わせを使用して,高接合密度の分子ブラシを合成する.
- 側鎖の特性と反応ステキオメトリーの接植密度に対する影響を調査する.
- 調節可能な特性を持つ高度なポリマーアーキテクチャを作成する.
主な方法:
- ATRP経由で線形ポリ・2-ヒドロキシエチルメタクリlate (PHEMA) を合成する.
- PHEMAの機能化は,アルキニル基をエステル化による.
- アジド末端のポリメリックサイドチェーン (PEO,ポリチレン,ポリ・...n-ブチルアクリラートを含む) とPHEMA-アルキンのバックボーンとのクリックカップリング.
主要な成果:
- 移植密度が最大88%の分子ブラシの成功合成は3時間以内に達成されました.
- 高い移植密度は,より低い分子量,より薄いサイドチェーン (例えば,PEO-N3,Mn = 775 g/mol) および高いモラ比を使用することと相関していました.
- その結果生じたブラッシュコポリマーは,分子あたり平均約186のサイドチェーンと約190kg/molの分子量を持っていた.
結論:
- ATRPとクリック化学を組み合わせた"grafting onto"メソッドは,密度の高い分子ブラシを合成するのに有効です.
- 接ぎ木密度は,サイドチェーン分子量,化学構造,反応ステキオメトリーを調整することで制御できます.
- この研究は,様々な分野での潜在的な応用を持つ高度なポリマーアーキテクチャへの道を提供します.
関連する概念動画
ATP and Macromolecule Synthesis
Biological macromolecules are organic compounds, predominantly composed of carbon atoms. The carbon atoms are covalently bonded with hydrogen, oxygen, nitrogen, and other minor elements. There are four major biological macromolecule classes: carbohydrates, lipids, proteins, and nucleic acids.
Most macromolecules are composed of single subunits, or building blocks, called monomers. The monomers combine with each other using covalent bonds to form larger molecules known as polymers.
Conversion of...
Most macromolecules are composed of single subunits, or building blocks, called monomers. The monomers combine with each other using covalent bonds to form larger molecules known as polymers.
Conversion of...
Radical 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...
Radical 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...
Anionic 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,...
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,...
Step-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...


