PATTERN FORMATION IN EVAPORATING DROPS

摘要: The redistribution of organic solutes during drop evaporation is a nanoscale self assembly process with relevance to technologies ranging from inkjet printing displays synthesis bio-smart interfaces for sensing and screening. Atomic force microscopy studies comparing the behavior different generation dendrimers surface chemistry in two solvent alcohols on mica substrates confirm that detailed morphologies condensed dendrimer ring structures resulting micro-droplet sensitively depend chemistry, solute rate generation. For dilute concentration studied here presence periodically i¥scallopedi¦ molecular rings ubiquitous. instability wavelength scalloped found be proportional width ring, similar observations rim dewetting holes. effect molecules obvious structure assembled rings. Varying chain length alcohol leads modification patterns. influence primarily reflects increase density number. evolution G2-50%C12-pentanol as function also described. High mobility phase transformation phenomena condensed, micro-scale are documented, again using atomic microscopy. Stratified undergo dramatic temperature, time dependent morphological changes associated large-scale rearrangements partial melting. These transformations produce consisting highly stable first monolayer equilibrium spherical cap shaped islands form at center each pre-existing scallop (creating i¥pearl necklacei¦ structure). Analysis island shapes reveals dependence contact angle line curvature (island size) varies systematically this system indicate potential creating complex, dendrimer-based multilevel macroscopic scale arrays using, example, droplet-on-demand or dip pen nanolithography techniques, coupled appropriate annealing stabilizing treatments.