Role of dynamic surface tension in slide coating

Contact-line fingering and rivulet formation in the presence of surface contamination

“…In typical applications, the liquid layer is driven over the substrate by an applied surface shear stress (caused by wind shear [1,2] or Marangoni force [3,4]) or by a body force (such as gravity or centrifugal force [5][6][7]) oriented tangent to the surface. The front of the liquid layer develops a ridge of liquid with larger layer thickness than the liquid layer as a whole.…”

Drying air-induced disturbances in multi-layer coating systems

“…The finding that surface tension varies only slightly with surface age indicates that surfactant is diffusing quickly in this case. The work of Valentini et al (1991) suggests that this could lead to large surface elasticities which would in turn increase the damping of free surface disturbances produced by external pressure disturbances. This is borne out here by related experiments which shows that the coating levels quickly when it is extracted prematurely from the dryer.…”

Short-time behavior of mixed diffusion-barrier controlled adsorption

“…(1) and (5), along with the initial and boundary conditions in Eqs. (7), (8), and (2), define completely the time evolution of the surfactant surface concentration, Γ (t). The equation of state (EOS), which relates Γ to the resulting reduction in the surface tension (or surface pressure), Π , corresponding to the generalized equilibrium adsorption isotherm in Eq.…”

“…(1), along with the boundary and initial conditions in Eqs. (15), (7), and (8), is similar to the partial differential equation (PDE) describing the diffusion in the exterior of a spherical cavity with a convection boundary condition at the surface of the cavity [73]. We used the method of Laplace transforms to solve this PDE, and the complete derivation is presented in Appendix A.…”

“…The time associated with the reduction of surface tension by surfactants and their mixtures is of great practical importance in various applications, including the development of therapeutic lung surfactants to treat the respiratory distress syndrome [1,2], 1 ink-jet printing [4], air-assist atomization [5], pesticide sprays [6], film coatings [7,8], and the generation of foams [9][10][11] and emulsions [12]. The dynamic aspects of surface tension are also important in phenomena like interfacial turbulence [13], the Marangoni effect [14], thin-film stability [13], surface rheology [13,15], drop impact [16][17][18][19][20], and the spreading of drops on surfaces [21][22][23][24].…”