ミセラー球から棒への移行の構造,体積,熱力学的特徴
Heiko Heerklotz1, Alekos Tsamaloukas, Katarzyna Kita-Tokarczyk
1Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland. heiko.heerklotz@unibas.ch
Journal of the American Chemical Society
|December 17, 2004
まとめ
ノニオン性表面活性剤は,水害性の表面積の減少とヘッドグループ脱水により,球から棒への移行を経験します. 鎖の順序は,表面活性物質の鎖の長さに基づいてこの移行に影響を与える可能性があります.
科学分野:
- 物理化学 物理化学
- マテリアルサイエンス 材料科学
- コロイド科学 コロイド科学
背景:
- ノニオン性表面活性剤は,温度上昇とともに球状のミセルから棒状の構造へと変化する,熱otropic 段階移行を示します.
- これらの移行を理解することは,薬物投与,洗浄剤,および強化された石油回収におけるアプリケーションに不可欠です.
研究 の 目的:
- マルチテクニックのアプローチを使用して,ノンイオン表面活性剤の球から棒への移行を包括的に特徴付ける.
- 移行に伴う熱力学,体積,構造の変化を明らかにする.
- 表面活性物質構造と溶媒 (H2O対D2O) が移行に及ぼす影響を調査する.
主な方法:
- 精密な熱力学的測定のための圧力乱動熱計 (PPC).
- 構造分析 (回転半径) のための小角中性子散射 (SANS).
- ハイドロダイナミック半径測定のためのダイナミック光散射 (DLS).
- 差分スキャニングカロミテリー (DSC) とイソテルミックタイトレーションカロミテリー (ITC) を用いて,熱および結合に関する研究を行う.
主要な成果:
- 移行温度,幅,部分体積,熱膨張,エンタルピー,熱容量の詳細な特徴.
- 容積パラメータの小さな,しかし重要な変化 (例えば, ~+2‰の部分体積変化) が観察されました.
- 回転半径や水力力学半径などの構造パラメータは,移行全体で定量化されました.
結論:
- スフィアからロッドへの移行は,水にアクセシブルな水性表面積の減少と,表面活性物質のヘッドグループの熱脱水による相互作用によって制御されます.
- 表面活性物質のアルキル鎖の漸進的な順序が,鎖の長さが重要な役割を果たし,移行に影響を及ぼすと仮定されています.
- この研究は,水溶液における非離子表面活性物質の相行動の詳細な熱力学および構造的な理解を提供します.
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