Microphase separation in ultrathin films of diblock copolymers with variable stickiness of one of the blocks to the surface

Surface interaction controlled microphase separation leading to the formation of a chemically heterogeneous surface nanopatterns in dry ultrathin films of A-B diblock copolymers is studied theoretically in the strong segregation limit. On a planar surface one of the blocks (A block) is strongly adsorbed, forming a tightly bound monomolecular layer (two-dimensional melt). Interaction of the second block (B block) with the surface can be varied from the strong attraction (two-dimensional conformation) to the strong repulsion (three-dimensional conformation) including regime of the weak interaction. Because of the strong incompatibility of A and B monomer units, chemically heterogeneous surface pattern can emerge. Depending on the block length ratio and on interaction parameters, various microstructures can be formed. They comprise surface micelles with prominent or flat disklike core, parallel stripes, and holelike micelles of monomer thick core and prominent corona (inverse disklike structure). The main geometrical parameters of the structures such as the size of the core and the period are determined as functions of the lengths of the blocks and of the interaction parameters.