物理化学学报 >> 1997, Vol. 13 >> Issue (05): 438-444.doi: 10.3866/PKU.WHXB19970510

研究论文 上一篇    下一篇

水/AOT/正庚烷微乳体系中水结构的FT-IR研究

李泉,李维红,翁诗甫,吴瑾光,徐光宪   

  1. 北京大学化学与分子工程学院，北京 100871
  • 收稿日期:1996-11-27 修回日期:1997-01-07 发布日期:1997-05-15
  • 通讯作者: 吴瑾光

FT-IR Study of Water Structure in Water/AOT/n-Heptane Microemulsion System

Li Quan,Li Wei-Hong,Weng Shi-Fu,Wu Jin-Guang,Xu Guang-Xian   

  1. College of Chemistry and Molecular Engineering,Peking University,Beijing 100871
  • Received:1996-11-27 Revised:1997-01-07 Published:1997-05-15
  • Contact: Wu Jin-Guang

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摘要：

 运用傅立叶变换红外光谱（FT-IR）对水／AOT／正庚烷微乳体系中水的微结构进行了研究，结果表明，随着体系中加水量的增大，水分子O－H伸缩振动的红外光谱由3493cm-1向低频移动至3417cm－1. 微乳体系中，水分子与AOT分子的磺酸基作用的同时，与Na+也有一定的作用，这两种离子对水分子O－H健的强度均有一定的影响. 磺酸基的作用使水分子中O－H伸缩振动向高波数方向移动，而Na+的作用与磺酸基相反，是使其向低波数方向移动. 根据微乳体系中水分子O－H伸缩振动红外光谱的二阶导数谱，对3050－3750cm－1范围内的红外光谱进行曲线拟合得到四个子峰，位于3590±20cm－1，3520±10cm－1，3465±10cm-1及3270±20cm-1处，分别被指认为自由水、磺酸基的结合水、本体水及钠离子的结水，AOT分子中羰基伸缩振动的红外光谱呈现非对称吸收峰，其强度比Ir（I1739／I1722）随体系中加水量的增大而减小，这是由于钠离子与羰基弱的相互作用随着加水量的增大而减弱引起的.

关键词: 红外光谱, 水, 曲线拟合, 微乳液, 琥珀酸-2-乙基已基磺酸钠

Abstract:

Microstructure of water in water/AOT/n-heptane microemulsion system has been studied using fourier transform infrared spectroscopy (FT-IR). Intensity and peak position of O-H stretching band of water in the system were found to change with water content Wo, i.e. the molar ratio of water to surfactant (H2O/AOT). Intensity of O-H stretching vibration in the range of 3050 and 3750 cm-1 increased with water content and the frequency was also found to vary from 3493 to 3417 cm-1 in the system with increasing Wo values (from 1 to 60). Four types of circumstance of water exist in the microemulsion system located around 3590±20 cm-1, 3520±10cm-1, 3465±10 cm-1 and 3270±20 cm-1 were estimated after O-H stretching bands were resolved by curve fitting. The stretching band of carboxide splitted into two peaks located at 1739±2cm-1and 1722±2 cm-1 and the intensity ratio Ir(I1739/I1722) decreased with water content. These variations are due to both the hydration of head-group and the different conformation in AOT molecule.

Key words: FT-IR;Water, Curve-fitting, sodium bis(2-ethylhexyl) sulfosuccinate(AOT), Microemulsion Solutions