在水性聚烯胺溶液中的超快速动态
1Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, 610 Taylor Road, Piscataway, NJ 08854-8087, USA. cshirota@mail.ecc.u-tokyo.ac.jp
Journal of the American Chemical Society
|December 26, 2001
概括
聚烯胺 (PAAm) 和胺 (PrAm) 溶液中的超快动态揭示了聚合物重定向是由宪法重复单元驱动的,而不仅仅是侧组. 这一发现适用于各种度和分子量.
科学领域:
- 物理化学 物理化学
- 聚合物科学 聚合物科学
- 频谱学是一种光谱学.
背景情况:
- 了解溶液中的聚合物动态对于材料性能至关重要.
- 聚烯胺 (PAAm) 是一种广泛使用的聚合物,但其溶液动态尚未完全理解.
- 五秒光谱学为超快速分子运动提供了一个窗口.
研究的目的:
- 为了研究水性多烯胺 (PAAm) 溶液的超快动力学.
- 为了确定负责PAAm在水中的重定向的分子运动.
- 为了比较PAAm的动态与一个模型化合物,胺胺 (PrAm).
主要方法:
- 五秒钟光学异质子检测拉曼诱导克尔效应光谱学 (OHD-RIKES).
- 研究了不同分子量 (1500和10,000) 和度 (0-40 wt%) 的PAAm水溶液.
- 使用胺 (PrAm) 作为PAAm宪法重复单元 (CRU) 的模型.
- 进行了短PAAm链的分子动力学模拟.
主要成果:
- PAAm和PrAm溶液动态显示了类似的时间尺度 (4-10 ps) 和度依赖.
- 重定向时间常数与度线性缩放,与指数粘度变化形成对比.
- PAAm与PrAm重定位时间的比率与它们的分子体积的比率相匹配.
- 五秒动态表现出因胺-胺和胺-水结合而产生的振荡.
结论:
- 在水性PAAm溶液中,主要的重定向动力学归因于整个结构重复单元的运动.
- 侧组运动本身无法解释观察到的聚合物动态.
- 键在这些溶液的超快动态中起着重要作用.
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