These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Influence of spacer of gemini on the interactions between cationic gemini surfactant and stearic acid in mixed monolayers.
    Author: Li R, Chen Q, Liu H, Hu Y.
    Journal: Langmuir; 2010 Jun 15; 26(12):9342-50. PubMed ID: 20394381.
    Abstract:
    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 < or = 8, 18-s-18 and SA are completely miscible, while partially miscible mixed monolayers are presented 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) < or = 0.67, SA could ionize completely and form a "cationic-anionic surfactant" with 18-s-18 owing to the electrostatic interaction between the head groups, while when X(SA) > 0.67, SA only partially ionizes, -COO(-) and -COOH coexist in mixed monolayers.
    [Abstract] [Full Text] [Related] [New Search]