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 can be set through the choice of free block dimensions. By depositing poly(styrene)-poly(ethylene oxide) (PS-PEO) diblock copolymers of different fractional composition of PEO on a surface by a Langmuir-Blodgett technique at different pressures, we show that the surface density of poly(styrene) aggregates 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 greater than that of the PS for all pressures less than that of the transition from a 2-dimensional to 3-dimensional film. The areal density of these resultant PS surface micelles can be tuned for a particular polymer composition and is linearly dependent on the deposition pressure which defines the region chosen on the phase diagram.