2. Formation of a bubble and a film

Bubbles are made by blowing air onto a frame that's been dipped in soapy water, just like kids do naturally. In reality, bubbles are basically spheres made of a thin film. This film, which is very thin (and becomes increasingly so as it drains), is stabilized by a bilayer of soap molecules but, more generally, by amphiphilic surfactant molecules (see § ) that enclose a layer of liquid water that is very thick compared to molecules of nanometer size (figure ).

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