Abstract
The properties of mixed monolayers composed of the cationic Gemini surfactant ([C 18H 37(CH 3) 2N + (CH 2) 3 N +(CH 3) 2C 18H 37],2Br +, abbreviated as 18-3-18,2Br −1) and stearic acid (SA) at the air/water interface were investigated by using a Langmuir film balance. The excess areas at the different mixed monolayer compositions were obtained and used to evaluate the miscibility and nonideality of mixing. Due to the electrostatic attractive interactions between 18-3-18,2Br −1 and SA, the excess areas indicated negative deviations from ideal mixing. Moreover, 18-3-18,2Br −1 and SA were miscible at the air/water interface, as was confirmed by atomic force microscopy (AFM) images of the LB films transferred onto mica substrates. The attenuated total reflectance (ATR) infrared spectra showed that SA in the mixed monolayers was ionized completely at a composition X SA = 0.67 and formed a “cationic–anionic surfactant,” i.e., the carboxylate, with 18-3-18,2Br −1 owing to the electrostatic interaction between the head groups.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
