Influence of spacer of gemini on the interactions between cationic gemini surfactant and stearic acid in mixed monolayers.
Influence of spacer of gemini on the interactions between cationic gemini surfactant and stearic acid in mixed monolayers.
复制标题
DOI：
10.1021/la1003287
复制
发表时间：
2010-04
期刊：
影响因子：
--
通讯作者：
Rong-xun Li;Qibin Chen;Honglai Liu;Ying Hu
中科院分区：
文献类型：
--
作者：
Rong-xun Li;Qibin Chen;Honglai Liu;Ying Hu
Mixed Langmuir-Blodgett (LB) films composed of a cationic gemini surfactant, [C(18)H(37)(CH(3))(2)N(+)-(CH(2))(s)-N(+)(CH(3))(2)C(18)H(37)],2Br(-) (18-s-18 with s = 3, 6, 8, 10 and 12), and a fatty acid of stearic acid (SA) were studied by the pi-A isotherm measurement, as well as by AFM and FT-IR. The analysis of the mean molecular area, the excess area and the excess Gibbs free energy from pi-A isotherms suggests the existence of attractive interactions between 18-s-18 and SA molecules in the mixed monolayers. The spacer group of 18-s-18 plays a very important role in the surface properties of 18-s-18/SA mixed monolayers. When s 8. Especially, in the latter case, when s = 12, phase separation appears in two composition regions of X(SA) = 0.4-0.75 and X(SA) = 0.75-0.85, respectively. This miscible phenomenon is confirmed by AFM observation. The result of FT-IR indicates that when X(SA) 0.67, SA only partially ionizes, -COO(-) and -COOH coexist in mixed monolayers.
