Hyperbranched Polymer Structures via Flexible Blade Flow Coating

Evaporative self-assembly has been shown to be a scalable method for organizing nonvolatile solutes, for example, nanoparticles; however, the influence of substrate surface energy on this technique has not been studied extensively. In this work, we utilized an evaporative self-assembly process based upon flexible blade flow coating to fabricate organized structures that have been modified to systematically vary surface energy. We focused on patterning of polystyrene. We observed a variety of polystyrene structures including dots, hyperbranched patterns, stripes, and lines that can be deposited on substrates with a range of wetting properties. We explained the mechanism for these structural formations based on the competition between Marangoni flow, friction, and viscosity. The development of this fundamental knowledge is important for controlling hierarchical manufacturing of nanoscale objects with different surface chemistries and compositions. (C) 2015 Wiley Periodicals, Inc.