离子在疏水性聚合物-水接口中被排除在外的程度不如氧化离子
Ryan L Myers1,2, Aoi Taira3, Chuanyu Yan1
1Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
The journal of physical chemistry. B
|December 31, 2024
概括
这项研究调查了pH值如何影响聚乙烯氧化物 (PNIPAM) 和聚乙烯氧化物 (PEO) 溶液的云点温度. 结果显示,离子 (H3O+) 促进了聚合物膨胀,而氧化物离子 (OH-) 则减少了它,从而影响了它们在霍夫迈斯特系列中的位置.
科学领域:
- 聚合物科学与工程 聚合物科学与工程
- 物理化学 物理化学
- 材料科学 材料科学 材料科学
背景情况:
- 聚合物溶液表现出温度依赖的相变,这对于药物输送和传感等应用至关重要.
- pH值和离子组成对这些转变的影响是复杂的,需要详细的研究.
- 了解离子-聚合物相互作用是定制聚合物在水溶液中的行为的关键.
研究的目的:
- 为了确定pH对聚乙烯氧化物 (PNIPAM) 和聚乙烯氧化物 (PEO) 溶液云点温度的影响.
- 阐明特定离子 (H3O+,OH-,Na+,Cl-) 在调节聚合物溶解性和相位行为的作用.
- 关联热力学,光谱学和分子动力学模拟数据,以全面了解离子-聚合物相互作用.
主要方法:
- 云点温度测量PNIPAM和PEO溶液在一个广泛的pH范围 (1.0-13.0) 在恒定的离子强度 (100毫米).
- 核磁共振 (NMR) 光谱检测聚合物构成和离子相互作用.
- 所有原子分子动力学 (MD) 模拟PNIPAM单体和小分子与离子相互作用.
主要成果:
- PNIPAM和PEO的云点温度在pH2.0和12.0之间基本稳定.
- 酸性条件 (100 mM HCl) 增加了云点温度,表明聚合物膨胀,而性条件 (100 mM NaOH) 降低了它.
- NMR和MD模拟证实,H3O+离子通过与PNIPAM相互作用促进胀,而OH-离子减少胀.
结论:
- 与普通离子相比,H3O+离子在疏水性聚合物接口中耗尽较少,这表明离子在霍夫迈斯特系列中的位置.
- OH-离子被排除在聚合物接口之外,将它们置于离子霍夫迈斯特序列内.
- 该研究提供了对pH依赖的聚合物行为和离子特异效应的详细了解,这对于设计先进的聚合物基材料非常有价值.
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