Foaming properties and the dynamics of adsorption and surface rheology of silk fibroin at the air/water interface

In this study, the surface adsorption, surface viscoelasticity and foamability of silk fibroin (SF) at the air/water interface are investigated and the relationship between the surface rheology and foaming properties is discussed. The SF molecules adsorb at the air/water interface and form viscoelastic surface films with high surface viscoelasticity modulus. Increasing concentrations of SF leads to thicker adsorbed layers and enhances the surface mechanical strength and foam stability. However, after the SF concentration exceeds a critical value, the surface dilatational modulus starts to decrease due to the imperfect arrangements of SF molecules at jamming state, and the surface tension and surface shear modulus do not show any significant changes at saturated adsorption.