Wetting phenomena on polymeric surfaces

Classic theory predicts a unique value of equilibrium contact angle, θ_o, for a given solid/liquid/fluid system. However, wetting phenomena are often very complicated in practice, with contact angle hysteresis being a major source of problems in interpretation. Contact angle variability is related to several factors, but we consider two which are particularly relevant to polymeric substrates - effects of orientation of molecular chains near the surface and local solid strain at the wetting front. A model is proposed to explain “stick-slip” motion of the triple line.