(651d) Controlling Ordering and Orientation in Nanostructured Thin Films through Combined Thermal and Solvent Annealing

Block polymer (BP) thin films potentially can be used to template large arrays of nanopatterns for advanced nanotechnologies. However, the practical utilization of directed BP self-assembly typically requires guide patterns of relatively small size scales. Two areas of recent progress in our research group include (1) the use of solvent vapor annealing to manipulate nanoscale morphologies and achieve well-oriented nanostructures, and (2) the use of engineered blade coating approaches to manipulate nanostructure orientation. In the first case, we are exploring the macroscopic alignment of BP nanostructures on a template-free substrate through raster solvent vapor annealing combined with soft shear (RSVA-SS). Our spatial control over nanoscale structures allows one to uniquely â??writeâ?? macroscopic patterns with microscopically aligned BP nano-features. This method significantly improves on previous approaches by eliminating the correlation between the BP alignment and shearing-pad shape, allowing continuous fabrication of highly ordered BP patterns in a two-dimensional manner. We demonstrate that complex patterns such as dashes, crossed lines, and curves can be imparted easily to thin films on featureless and untreated substrates. Furthermore, the ability to expand or shrink the â??writingâ? size of the oriented regions from millimeters to centimeters provides a unique handle for manipulating pattern formation in an on-demand fashion. In the second case, we are exploring methods for the simultaneous deposition and nanoscale orientation control of block copolymer thin films. These techniques facilitate the generation of well-defined nanoscale features in a manner that is adaptable to continuous processing.