Self-Alignment of Cylinder-Structured Silicon-Containing Block Copolymer Films

The formation of well-ordered perpendicular cylinders of star-block copolymers (BCPs) composed of polystyrene and poly(dimethylsiloxane) blocks with high aspect ratio can be achieved by using a combination of architecture effect (entropy effect) and surface air plasma treatment (enthalpy effect). An interesting morphological evolution from disordered texture to hexagonally packed cylinders with perpendicular orientation can be found at which the perpendicular cylinders simultaneously develop from the top surface of the thin film and also the bottom substrate through the nucleation and growth process followed by the formation of span-thru cylinders through the self-alignment process with the improvement of lateral ordering. Those results suggest a unique mechanism for the induced orientation and lateral ordering of BCP thin films through the nucleation and growth process followed by self-alignment process; this finding may provide an insight for the mechanisms of BCP self-assembly in the thin-film state to give the nanopatterns with controlled orientation and long-range ordering.