New Features on the Phase Transitions of Behenic Acid Monolayers as Unveiled by 2D‐Compressibility Coefficient

Abstract

Phase behavior of Langmuir monolayers of behenic acid (BeA) has been examined by two-dimensional compressibility. It was found that phase transitions of BeA could be classified into two distinct categories, named Type-I and Type-II in this work. The former is typified by a positive peak on the compressibility-pressure (β-π) curve, indicating the transition can occur itself in a way of collapse from the initial structure. The latter is characterized by a dropping step on the β-π curve, implying that it cannot happen itself and the driven force is continuous compression. For BeA molecules, compressibility coefficients at the initial and final state are the same, β i ＝β f , for Type-I phase transition from L 2 to L 2 ' state, whilst β i ＞β f for Type-II phase transition from L 2 ' state to S state.

Structural Properties of the Liquid Ordered Phase of Phosphatidylcholine/Stigmasterol Liposomes: A Synchrotron X-Ray Diffraction Study

“…32,34,36 They reflect the repeat spacings of hexagonal or quasi-hexagonal arrangements of acyl chains as depicted in a previous publication. 37 The experimental results that the d-spacing of Lo phase varies from 0.422 nm to 0.460 nm may imply that the Lo phase owns both the character of gel phase and the character of Lα phase, depending on the composition of the binary mixture and temperature. This is consistent with the conclusion that the character of Lo phase covers the characters of both gel phase and Lα phase.…”