Controlled patterning of diblock copolymers by monolayer Langmuir-Blodgettdeposition

Nonlithographic techniques for patterning structures on the nanometer Scale can provide methods for direct control of particle spacing at surfaces. By using diblock copolymers, the surface density of a film can be established by the properties and area of the anchoring block, and the feature sizes c an be set through the choice of free block dimensions. By depositing poly(s tyrene)-poly(ethylene oxide) (PS-PEO) diblock copolymers of different fract ional composition of PEO on a surface by a Langmuir-Blodgett technique at d ifferent pressures, we show that the surface density of poly(styrene) aggre gates can be controlled. The separation of PS aggregates on the surface is ensured by selection of the PEO composition so that its projected area is g reater than that of the PS for all pressures less than that of the transiti on from a 2-dimensional to 3-dimensional film. The areal density of these r esultant PS surface micelles can be tuned for a particular polymer composit ion and is linearly dependent on the deposition pressure which defines the region chosen on the phase diagram.