Structure and energy of liquid foams

• Coherent overview of recent advances concerning foam structure and energy over the entire range of liquid fraction
• Introduction to the structural properties for a wide readership with relevance for the development of novel foam-based materials
• Systematic comparison between ordered and disordered foams over a range of polydispersities
• Summary of experimental data and various models for the variation of relative surface excess as a function of liquid fraction
• Brief review of experimental, computational and analytical techniques related to foam structure

We present an overview of recent advances in the understanding of foam structure and energy and their dependence on liquid volume fraction. We consider liquid foams in equilibrium for which the relevant energy is surface energy. Measurements of osmotic pressure can be used to determine this as a function of liquid fraction in good agreement with results from computer simulations. This approach is particularly useful in the description of foams with high liquid content, so-called wet foams. For such foams X-ray tomography proves to be an important technique in analysing order and disorder. Much of the discussion in this article is also relevant to bi-liquid foams, i.e. emulsions, and to solid foams, provided that the solidification preserves the structure of the initially liquid foam template.

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