Poly(styrene-co-butadiene) random copolymer thin films and nanostructures on a mica surface: morphology and contact angles of nanodroplets.

The self-assembly of poly(styrene-co-butadiene) random copolymers on mica surfaces was studied by varying solution concentrations and polymer molecular weights. Toluene solutions of the poly(styrene-co-butadiene) samples were spin coated onto a mica surface and the resulting polymer morphology was investigated by atomic force microscopy. At higher concentrations, thin films formed with varying thicknesses; some dewetting was observed which depended on the molecular weight.

Formation, Evolution, and Extinction of Standing Waves in Evaporation from Pores.

We report on the formation, evolution, and extinction of standing waves (SWs) detected by infrared measurements at the upper region of a curved meniscus interface pinned at the mouth of a horizontally positioned capillary pore. The SWs are clear and strong in acetone but absent in ethanol for both tube sizes investigated (1-2 mm diameter). Dependent upon the tube size and the initial liquid filling ratio, the SWs start sooner for a lower filling ratio.

Three-dimensional Marangoni cell in self-induced evaporating cooling unveiled by digital holographic microscopy.

A digital holographic microscope has been used to trace the trajectory of a tracer particle inside the liquid phase of an evaporating meniscus formed at the mouth of a 1-mm2 borosilicate tube filled with ethanol. The Marangoni flow cells are generated by the self-induced differential evaporating cooling along the meniscus interface that creates gradients of surface tension which drive the convection. The competition between surface tension and gravity forces along the curved meniscus interface disrupts the symmetry due to surface tension alone.