Photon control of liquid motion on reversibly photoresponsive surfaces.

The movement of a liquid droplet on a flat surface functionalized with a photochromic azobenzene may be driven by the irradiation of spatially distinct areas of the drop with different UV and visible light fluxes to create a gradient in the surface tension. In order to better understand and control this phenomenon, we have measured the wetting characteristics of these surfaces for a variety of liquids after UV and visible light irradiation. The results are used to approximate the components of the azobenzene surface energy under UV and visible light using the van Oss-Chaudhury-Good equation.

Rheological properties of nanopowder alumina coated with adsorbed fatty acids.

The rheological properties of a nanosized alumina powder coated with fatty acid steric stabilizers of varying chain length were investigated. The storage and loss moduli of the complex modulus were measured to characterize the behavior of the flocculated systems. As chain length increased, there was a transition from an elastic response to fluid behavior.