初期に均質な状態から急速にポリメリ化した二次元共性有機構造のメカニズム学的な研究
Brian J Smith1, William R Dichtel
1Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University , Ithaca, New York 14853-1301, United States.
Journal of the American Chemical Society
|June 4, 2014
まとめ
私たちは,同質的な条件下で共性有機フレームワーク (COF) の成長を研究しました. これにより,COF-5形成の動態を定量化し,材料の質を改善する反応パラメータを特定することができました.
科学分野:
- マテリアルサイエンス 材料科学
- ポリマー化学のポリマー化学について
- ナノテクノロジー ナノテクノロジー
背景:
- 協和有機フレームワーク (COF) は,調節可能な構造と高い表面積を持つ高度な多孔性材料です.
- COFの核形成と成長運動を理解することは,それらの結晶性を改善し,合理的な合成を可能にするために不可欠です.
- COFの形成を研究する現在の方法は,異質な反応条件によって制限されています.
研究 の 目的:
- 均質な反応条件下での2Dボロナートエステル結合COF-5形成の運動学を調査する.
- 反応パラメータとCOF材料の品質との間の最初の定量的なリンクを確立する.
- COFの核形成と成長プロセスに関する機械的洞察を得るために.
主な方法:
- 完全に溶解するモノマー条件下でのCOF-5の合成.
- 光学的な度測定を用いたCOFの降水率の定量化.
- 温度依存 (アーレニウス) と速度法則の決定を含む運動分析.
主要な成果:
- COF-5の形成は,均質な条件下で数分以内に発生することが観察されました.
- この反応はアーレニウス温度依存を示し,活性化エネルギーは22~27 kcal/molであった.
- 速度の法則は,ボロン酸とカテキール分子の場合は二次性であり,メタノール濃度では逆の二次性であると判断されました.
- ステイキオメトリック水添加により,結晶石領域面積が4倍に増加し,材料の品質に対する合理的な制御が実証されました.
結論:
- 均質な合成条件により,COF形成の厳格な運動研究が可能です.
- この研究は,COFの成長に関する最初の定量運動データと機械的洞察を提供します.
- 反応条件,特に水ステキオメトリを合理的に制御して,COF結晶石領域のサイズと材料の質を大幅に向上させることができます.
関連する概念動画
Radical Chain-Growth Polymerization: Mechanism
2.9K
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...
2.9K
Cationic Chain-Growth Polymerization: Mechanism
2.1K
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...
2.1K
Anionic Chain-Growth Polymerization: Mechanism
1.7K
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...
1.7K
Ziegler–Natta Chain-Growth Polymerization: Overview
2.3K
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...
2.3K
Radical Chain-Growth Polymerization: Overview
2.7K
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...
2.7K
Polymers
32.8K
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...
32.8K


