结构,体积和热力学特征的micellar球到杆的过渡
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
概括
非离子表面活性剂经历由减少的疏水性表面积和头组脱水驱动的球体到杆的过渡. 链条排序可能会影响这种过渡,这取决于表面活性剂的链条长度.
科学领域:
- 物理化学 物理化学
- 材料科学 材料科学 材料科学
- 体科学 体科学 体科学
背景情况:
- 无离子表面活性剂表现出热热的相位过渡,随着温度的增加,从球状细胞转变为棒状结构.
- 了解这些转变对于药物输送,洗剂和增强石油回收的应用至关重要.
研究的目的:
- 使用多技术方法全面描述非离子表面活性剂从球体到杆的过渡.
- 阐明伴随过渡的热力学,体积和结构变化.
- 研究表面活性剂结构和溶剂 (H2O与D2O) 对过渡的影响.
主要方法:
- 压力扰动热量计 (PPC) 用于精确的热力学测量.
- 小角度中子散射 (SANS) 用于结构分析 (旋转半径).
- 动态光散射 (DLS) 用于水力动力半径的确定.
- 差分扫描热量计 (DSC) 和异热定位热量计 (ITC) 用于热和结合研究.
主要成果:
- 过渡温度,宽度,部分体积,热膨胀,度和热容量的详细表征.
- 观察到体积参数的小但显著的变化 (例如, ~+2‰的部分体积变化).
- 像旋转半径和水力动力半径这样的结构参数在整个过渡过程中被量化.
结论:
- 从球体到杆的转变是由减少水可访问的疏水表面积和表面活性剂头组的热脱水的相互作用决定的.
- 表面活性剂基链的逐渐排序被假定会影响过渡,链长度起着关键作用.
- 该研究提供了对水溶液中非离子表面活性剂相位行为的详细的热力学和结构理解.
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