Study on the Structure, Shape, and Solution Properties of nonionic Surfactant Micelles

非离子表面活性剂胶束的结构、形状及溶液性质研究

• 批准号: 14550849
• 负责人: EINAGA Yoshiyuki
• 金额: $ 2.3万
• 依托单位: Nara Women's University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14550849/
• 关键词: Surfactant; Polyoxyethylene Alkyl Eter; Micelle; Light Scattering; Radius of Gyration; Hydrodynamic Radius; Wormlike Spherocylinder; Phase Diagram; 静的光散乱; 動的光散乱; 拡散係数

In this work, we have chracterized threadlike micelles of typical nonionic surfactants polyoxyethylene alkyl ether C_iE_j i and j denote the numbers of methylene groups in the alkyl chain and of oxyethylene groups in the oxyethylene chain, respectively) by static (SLS) and dynamic light scattering (DLS) measurements. The surfactant samples examined are C_<12>E_5, C_<12>E_6, C_<12>E_7, C_<14>E_6, C_<14>E_8, C_<16>E_7, C_<16>E_8, C_<18>E_7, C_<18>E_8.The concentration dependence of the SLS results, the relationships between radius of gyration and micellar molar mass, the relationships between hydrodynamic radius and micellar molar mass are found to be well represented by the corresponding theories with wormlike spherocylinder model, thereby indicating that the micelles formed of the above surfactants assume flexible cylindrical shape. It has been found that the micelles grow in length with increasing concentration and with raising temperature, to greater extent for larger i (or for the longer hydrophobic groups). The cross-sectional diameter has varied from 2.4 to 3.0 nm depending on the valuses of i and j, while the average spacings among hydrophilic groups of the surfactant molecules on the micellar surface are ca. 1.2 -1.5 nm, almost independent of the surfactant species. The micellar solutions have been phase-separated with raising temperature, revealing the LCST behavior with lower LCST for the surfactant with longer hydrophobic chain. It hs been shown that the C_<12>E_6 micelles cause transition of the micellar shape from wormlike spherocylindrical shape to prolate ellipsoid with uptake of n-dodecane and n-dodecanol. Here, the micelles have been disintegrated into smallar size by including the former oil, while they have grown in size by inchsding the latter.

本文用静态光散射（SLS）和动态光散射（DLS）方法研究了典型的非离子表面活性剂聚氧乙烯烷基醚（C_iE_j，i和j分别表示烷基链上亚甲基的数目和氧杂环烷基链上氧杂环的数目）的线状胶束。所考察的表面活性剂样品为C_<12>E_5、C_<12>E_6、C_<12>E_7、C_<14>E_6、C_<14>E_8、C_<16>E_7、C_<16>E_8、C_<18>E_7、C_<18>E_8。SLS结果的浓度依赖性、回转半径与胶束摩尔质量的关系、流体动力学半径与胶束摩尔质量的关系均能用相应的蠕虫状球柱模型理论很好地描述，表明上述表面活性剂形成的胶束呈柔性圆柱形。已经发现，胶束的长度随着浓度的增加和温度的升高而增长，对于较大的i（或对于较长的疏水基团），增长的程度更大。胶束的横截面直径随i和j的不同而变化，为2.4 ~ 3.0nm，表面活性剂分子亲水基团间的平均间距约为2.5 ~ 3.0nm。1.2~ 1.5 nm，几乎与表面活性剂种类无关。随着温度的升高，胶束溶液发生相分离，表明疏水链较长的表面活性剂具有较低的LCST。结果表明，<12>随着对正十二烷和正十二醇的吸收，C_ E_6胶束的形状由蠕虫状的球柱体向长椭球体转变。在这里，胶束已被分解成较小的大小，包括前者的石油，而他们已经长大的大小，通过inchsding后者。