Influence of the contact angle of silica nanoparticles at the air-water interface on the mechanical properties of the layers composed of these particles

International audienceWe have studied the properties (surface pressure, compression and shear moduli, texture) of silica nanoparticle layers at the air-water interface. Particle hydrophobicity or equivalently the contact angle between particles, air and water, is the main factor that influences surface organisation and surface elastic moduli. The surface layers are denser for particles of higher hydrophobicity. The compression and shear moduli, as well as the yield and melt strains, present a maximum for contact angles around 90°. The dependence of mechanical properties on particle hydrophobicity is closely related to the foamability and stability of the foams made from dispersions