水／AOT／正庚烷微乳体系中磺酸根水化作用的FT—IR研究

运用傅立叶变换红外光谱（FT－IR）对水／琥珀酸（乙基已基）磺酸钠（AOT）／正庚烷微乳体系中磺酸根的水化作用进行了研究．由于微乳体系中水分子与表面活性剂分子的相互作用，S＝O对称伸缩振动的红外吸收峰向低频方向移动．体系中的加水量W0（水与AOT的摩尔比）由0.5增大至25时，磺酸根对称伸缩振动的红外吸收峰由1051．39cm－1向低频移动至1046．15cm－1．同时，由于Na 的不对称作用，AOT分子中磺酸根反对称伸缩振动分裂成两个吸收峰，分别位于正215cm-1及1245cm－1附近，两个劈裂峰的距离及各自的峰面积均随体系中加水量的变化而变化，应用二阶导数、傅立叶退卷积及曲线拟会等分辨率增强技术可更清楚地反映出这个二重峰的变化情况．固体AOT分子中碳酸根反对称伸缩振动分裂的两个峰之间频率的差值约为42cm－1，形成微乳液以后，这两个峰的差值变小，W0为20时，这两个峰频率的差值逐渐减小到29cm-1，这些变化与磺酸根的水化程度直接相关

FT-IR Study on the Hydration of Sulfonate in Water/AOT/n-Heptane Microemulsion system

Hydration of sulfonate in water/AOT/n-heptane (AOT = sodium bis (2-ethylhexyl) sulfosuccinate) microemulsion system has been investigated by means of FT-IR.The results show that the hydration of sulfonate in the system leads to a shift of symmetricsulfonate stretching mode from 1051. 39 cm-1 to 1046. 15 cm-1 in the infrared spectra withthe increase of the molar ratio of water to AOT, W0 The formation of microemulsionsweakens the interaction between counterion Na and -SO3-, groups, compared with that inthe solid state AOT. The splitting of the antisymmetric sulfonate stretching mode in the in-frared spectra reduces from ca. 42 cm-1 to 29 cm-1 upon the addition of water into the sys-tem. The intensity of ~ 1215 cm-1 increases, while the peak of ~ 1245 cm-1 decreases corre-spondingly with the increase of W0.