Morphology Observation of Novel 3, 4-Bis-Alkyloxycarbonyl-Hexanedioic Acid Monolayer on Water Surface by Dropping Method

We have investigated the morphology of novel 3, 4-bis-alkyloxycarbonyl-hexanedioic acid monolayer (alkyl chain number n = 12, 14, and 16) formed on the water surface by dropping method using Surface Tension measurement (STm) and Brewster Angle Microscopy (BAM). Surfactant of 3, 4-bis-alkyloxycarbonyl-hexanedioic acid has a gemini type structure. π-A isotherm curves (STm) of two gemini surfactants of n = 12 and 14 showed gradual increase in surface pressure, while that of n = 16 showed gradual increase, a stagnant range and finally steep increase. BAM observation showed each image corresponding to the result of STm measurement. From STm and BAM results of surfactants, it is found that surfactant of n = 12 and 14 form Liquid-Expand (LE) type monolayer, while that of n = 16 formed Liquid-Condensed (LC) type monolayer including LE-LC phase transition.