It has long been recognized that roughness on the nanometer scale can dramatically alter the wetting properties of solid surfaces. So far, scientific and engineering efforts have focused on the wetting of macroscopic surfaces, yet surface roughness also modulates the wettability of colloidal particles. The latter is vital for particle assembly in fluid-fluid interfaces, a crucial step in the formation of particle-stabilized emulsions and foams, which have many industrial applications. We demonstrate that variations in the particle roughness alone can determine whether particles stabilize water-in-oil or oil-in-water emulsions, and precisely how stable such emulsions will be. First, we introduce a method to produce surface coatings with different roughness but identical surface chemistry that can be applied to both macroscopic substrates and micron-sized particles. Then we characterize the morphology of these surface coatings and correlate it with their wetting properties and with the emulsification properties of coated microparticles.

Nanoscale roughness of colloidal particles and its effect on particle-stabilized emulsions

244th National Meeting (2012)

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