(27b) Thin Colloidal Films: Applications to Concentrated Suspensions, Foams and Emulsions

Thin films of suspensions of nanometer sized particles (nanofluids), surfactant micelles, globular proteins or macromolecules are used in a variety of technological contexts. For example, their spreading, wetting and adhesion behavior on solid surfaces can yield materials with desirable structural and optical properties. Also, thin films separating the dispersed phase are generally considered to be the key structural elements of foams and emulsions containing surfactant micelles or hydrocolloids. This lecture will present an overview of the work carried out in our laboratory using the novel hybrid surface force apparatus referred to as the capillary force balance, in conjunction with differential interference microscopy to probe the structuring of colloidal species in thin films. This work has clearly shown that the resulting long-range structural forces stabilizing thin colloidal films impact a diverse range of systems including phenomenon involving surfactants and detergency, proteins in thin film and stabilizing of foams and emulsions. Results of computer simulations and statistical mechanical theories are compared with the experiments.