EFFECT OF CHAIN TERMINATION CHEMISTRY AND MOLECULAR-WEIGHT ON DYNAMICWETTING OF POLYMER LIQUIDS

The dynamic wetting behavior of methyl- and hydroxyl-terminated poly(d imethylsiloxane) with a range of molecular weights and viscosities is discussed. Direct imaging of the fluid/air interface within 20 mum of the contact line was used to probe this behavior. Models which account for the unique hydrodynamics near a moving contact line accurately de scribe the measured interface shapes. Our measurements provide a geome try-independent characterization of the dynamic contact angle and thus may be transferred to any macroscopic geometry. The dynamic wetting b ehavior is more sensitive to the chain termination chemistry than to t he variations in molecular weight and viscosity. Implications for the unique hydrodynamics occurring near the contact line and governing the spreading are explored.