Stability of stearic acid monolayers on Artificial Sea Water

作者：Brzozowska A M; Duits M H G^*; Mugele F

来源：Colloids and Surfaces A: Physicochemical and Engineering Aspects , 2012, 407: 38-48.

DOI：10.1016/j.colsurfa.2012.04.055

• Stearic acid
• Monolayer stability
• Artificial Sea Water
• Langmuir trough
• Imaging ellipsometry

We studied the formation and stability of stearic acid (SA) based films on aqueous sub-phases via Langmuir trough and imaging ellipsometry experiments. The aqueous phase was based on Artificial Sea Water (ASW), a multicomponent salt solution with a total molarity of 0.53. The composition of this solution was varied via dilution (1,10 and 100 times) and adjustment of the pH (3, 7, 10). Also water sub-phases without the ASW salts were studied. Pressure-area isotherms of the SA monolayers show an enhanced stability of the film against fracture when the pH and/or the salt concentration of the sub-phase are increased. Isobars of SA measured below the pressure needed for film fracture, indicate distinct mechanisms for loss of material: (1) at low pH and salt concentration, three dimensional (3D) structures are formed at the air/water interface via nucleation and growth and (2) at high pH and salt concentration, diffusion-controlled dissolution of molecules in the sub-phase occurs. The formation of multilayer structures was corroborated with ellipsometry images of the films after Langmuir-Blodgett transfer.

• 出版日期2012-8-5