Molecules in a thin bubble membrane

A simple method for generation of a stable bubble membrane from an aqueous solution of sodium dodecyl sulfate (SDS) is reported. The method involves repeated boiling of an aqueous solution of SDS with addition of fresh SDS in the end. An air bubble is blown over a small inverted beaker containing a portion of the solution. With time the bubble loses water and other components and results in a thin membrane. The membrane thus obtained is stable for minutes. Time-dependent UV-vis spectroscopic measurements are used to ascertain the change in thickness of the bubble with time. FTIR spectroscopic measurements have been utilized to follow the change in chemical composition of the bubble. The bubbles containing Rhodamine B and Rhodamine 6G dyes reveal that these dyes remain in the bubbles even if they become very thin. The visible absorption spectra of these dyes indicate that these dyes are possibly in the aqueous layer which may be present in the thin bubble membrane.