水溶液における対極電荷のポリイオン結合の原動力:エンタルピック,エントロピック,しかし静電的ではない
Jingcheng Fu1, Joseph B Schlenoff1
1Department of Chemistry and Biochemistry, The Florida State University , Tallahassee, Florida 32306, United States.
Journal of the American Chemical Society
|January 16, 2016
まとめ
ポリマー結合の原動力は 静電性だけではありません 特定のイオンペアリングの影響を受けた水の乱れは,エンタルピー変化に大きく影響し,自由エネルギーは主にエントロピーによって駆動されます.
科学分野:
- ポリマー科学
- 物理化学
- 溶液化学
背景:
- 溶液中の対極電荷のポリマー結合は,伝統的に静電相互作用に起因する.
- これらの静電力はエントロピック (対陽放出) とエンタルピック (クーロンビック吸引) のコンポーネントで構成されています.
- 連続体静電学理論では,小さなエクソサーム/エンドサームをクーロンビック相互作用の証拠として解釈することが多い.
研究 の 目的:
- ポリエレクトロライト結合のための静電と特定のイオンペアリングメカニズムを比較する.
- ポリカチオン-ポリアニオン複合化中のエンタルピー変化の起源を調査する.
- ポリマー結合におけるカウンターイオンと水構造の役割を解明する.
主な方法:
- 静電対特定のイオンペアリングモデルの対比比較.
- ハーフマイスターのカウンターリオンとポリディアルメチルアモニウム (PDADMA) を使った.
- 水のOH振動を研究し,水の乱れを評価するためにラマン散布を使用した.
主要な成果:
- エンタルピーの変化は キュロンビック引力だけではなく 水の乱れによるものだと判明した.
- ラーマンスペクトロスコーピーは,コンテリオン同一性と相関する水の構造の変化を明らかにした.
- 複合性の自由エネルギーは,様々な塩分濃度において主にエントロピーであった.
結論:
- 水の構造の変化を含む特定のイオンペアリングとイオン交換メカニズムは,ポリエレクトロライト関連を理解するために重要である.
- 従来の静電モデルでは 熱力学的駆動力を完全に捉えられないかもしれません
- ポリマーの複合性のエネルギー学には,水構造に対するカウンターイオン特異的な効果が重要な役割を果たします.
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