0000000000204908
AUTHOR
V. Melzer
Structure features and phase behaviour of amphiphilic N-tetradecyl-β-hydroxy-propionic acid amide monolayers
Abstract Two phase transitions of N-tetradecyl-β-hydroxy-propionic acid amide monolayers at the air/water interface were studied by means of pressure/surface area ( π A ) isotherms, Brewster angle microscopy (BAM) and synchrotron X-ray grazing-incidence diffraction (GID). At T≤15 °C the π A isotherms show two plateau regions indicating two first-order phase transitions. In the first main transition from the lowdensity fluid-like phase to a condensed phase, dendritic growth of condensed phase domains with six main growth directions was observed by BAM. A second transition from a condensed phase with large tilt angle to a condensed phase with smaller tilt angle and a denser arrangement of mol…
Brewster angle microscopy and X-ray GID studies of morphology and crystal structure in monolayers of N-tetradecyl-γ,δ-dihydroxypentanoic acid amide
First-order phase transitions from the low-density fluidlike phase to the condensed phase of monolayers of N-tetradecyl-γ,δ-dihydroxypentanoic acid amides at the air−water interface have been studied by π−A isotherms, Brewster angle microscopy (BAM), and synchrotron X-ray grazing incidence diffraction (GID). The thermodynamic differences between enantiomeric and racemic monolayers are too small to be measured. However, chiral discrimination is observable in the macroscopic domain morphology by BAM. The domains of the condensed phase grow dendritically. The characteristic shapes of domains of the pure S and R enantiomers are mirror images of each other. The domains of the racemic mixture are…