Micro-phase separation in binary mixed langmuir monolayers: correlation between molar fraction and area fraction

摘要

Correlation between molar fraction and area fraction in micro-phase separated structures formed In binary mixed Langmuir monolayers of arachidic acid (C20) and a perfluoropolyether amphiphile (PFPE) has been examined. On the water surface, C20 and PFPE separate into fully condensed micro-domains and a largely expanded phase, respectively. The area fraction of the condensed phase domains is estimated by two different ways: one is by analyzing atomic force microscope (AFM) images and the other is calculated from π-A isotherm data assuming complete immiscibility of the film components in the monolayers. Two area fractions are in agreement with each other, and increase exponentially with increase in molar fraction. Our results ensure the complete phase separation of the two film components on the water surface, the monolayer transfer without any structural changes, and the fruitfulness of digital image analysis for the evaluation of two-dimensional organized structures.