Visualization of first- and second-order phase transitions in eicosanol monolayers using Brewster angle microscopy

Abstract

In the intermediate temperature and the upper pressure regions, the phase diagram of an eicosanol monolayer consists of four phases: (1) one normal condensed high-pressure phase, A', (2) and (3) two high-pressure superliquids, Rot I and Rot II, and (4) one low-pressure phase, C. The phase transitions A'/C and Rot II/C are of second order and correlated with a collective tilting of the molecules. The phase transition C/Rot I, however, is of first order and correlated with formation and growth of nuclei consisting of tilted or normally oriented molecules, depending on the direction of the transition. The kinetics of the

Temperature dependence of the organization and molecular interactions within phospholipid/diacetylene Langmuir films

“…The interactions and organization of two molecular components occupying the same two-dimensional space have been explored by thermodynamic [6,7] and microscopic [2,[8][9][10] approaches. Monolayers component miscibility [6], distribution [11] domain growth [12], nucleation [13], phase transition [14], and collapse [15] processes have attracted great interest ever since the early pioneering studies of Langmuir films [16,17]. Elucidating the association and cooperative phenomena of lipids and their interactions with other components in film environments is particularly important because of the significance of lipid assemblies in biological systems, specifically cellular membranes [18].…”

Phase Behaviors of Giant Surfactants with Different Numbers of Fluorinated Polyhedral Oligomeric Silsesquioxane “Heads” and One Poly(ethylene oxide) “Tail” at the Air–Water Interface

“…G to L transition generally is the first-order transition and theoretically there should be a transition plateau in isotherms. 57,58 However, the plateau of the G and L coexistence is not manifested in the experimental isotherm because the surface pressure of the G state is extremely low, 0.001−0.01 mN/m. However, the BAM images can reflect the coexistence state of G and L. Figure 3a The isotherms of (FVPOSS) 2 −PEO 227 and (FVPOSS) 3 − PEO 227 both show two narrow non-horizontal plateaus.…”

Effect of Surface Freezing on Stability of Oil-in-Water Emulsions

“…Adsorbed films of soluble amphiphiles exist in three different physical states called gaseous, expanded, and condensed states, which respectively correspond to two-dimensional gas, liquid, and solid phases. [1][2][3][4][5][6][7][8][9] Among these, the condensed film formation has largely been limited to sparingly water-soluble nonionic amphiphiles such as long-chain alkanols. 1,2,[4][5][6][7][8][9] In 2000, McKenna et al reported that a mixed monolayer of hexadecylltrimethyl ammonium bromide (CTAB) and n-tetradecane (C14) underwent a first-order freezing transition at the air-water interface upon cooling.…”

“…[1][2][3][4][5][6][7][8][9] Among these, the condensed film formation has largely been limited to sparingly water-soluble nonionic amphiphiles such as long-chain alkanols. 1,2,[4][5][6][7][8][9] In 2000, McKenna et al reported that a mixed monolayer of hexadecylltrimethyl ammonium bromide (CTAB) and n-tetradecane (C14) underwent a first-order freezing transition at the air-water interface upon cooling. 10 Subsequently, Sloutskin et al carried out surface tension and X-ray reflectivity measurements on mixed monolayers of CTAB and the series of n-alkanes and confirmed that the thickness of the surface frozen monolayers increased with n-alkane chain length for dodecane  heptadecane and found that the low-temperature phase was a hexagonally packed two-dimensional solid phase a single monolayer thick, with upright, conformationally ordered chains.…”