We investigate the phase behavior of symmetric AB diblock copolymers confined into a thin film. The film boundaries are parallel, impenetrable and attract the A component of the diblock copolymer. Using a self-consistent field technique [M.W. Matsen, J.Chem. Phys. 106, 7781 (1997)], we study the ordered phases as a function of incompatibility χ and film thickness in the framework of the Gaussian chain model. For large film thickness and small incompatibility, we find first order transitions between phases with different number of lamellae which are parallel oriented to the film boundaries. At high incompatibility or small film thickness, transitions between parallel oriented and perpendicular oriented lamellae occur. We compare the self-consistent field calculations to Monte Carlo simulations of the bond fluctuation model for chain length N = 32. In the simulations we quench several systems from χN = 0 to χN = 30 and monitor the morphology into which the diblock copolymers assemble. Three film thicknesses are investigated, corresponding to parallel oriented lamellae with 2 and 4 interfaces and a perpendicular oriented morphology. Good agreement between self-consistent field calculations and Monte Carlo simulations is found. I. INTRODUCTION.Amphiphilic polymers are model systems for investigating mechanisms of self-assembly. Joining chemically distinct polymers -A and B -at their ends to form an AB diblock copolymer prevents macrophase separation of the two species. In order to reduce the number of energetically unfavorable interactions between distinct blocks in a melt, the molecules self-assemble into complex morphologies. The morphology is selected via a delicate balance between the free energy cost of the internal interfaces and the conformational entropy loss as the molecules stretch to fill space at constant density. The phase diagram in the bulk has been investigated in much detail as a function of the relative length of the blocks f and the incompatibility χN [1-3]. The morphologies found in copolymer melts and copolymer/homopolymer mixtures [4] resemble the spatially structured phases of other amphiphilic systems (e.g., lipid/water mixtures).From a theoretical point of view, polymeric systems are particularly convenient for investigating mechanisms of self-assembly. Only a small number of parameters describe the system, i.e., the fraction f of A monomers in the diblock, the molecule's end-to-end distance R e and the incompatibility χN , where χ denotes the repulsion between monomers of different species and N the number of monomers per molecule. In general, polymeric systems are well describable by self-consistent field theories using the Gaussian chain model [5][6][7]. For a wide range of temperature the theory accurately calculates the excess quantities of the internal interfaces (e.g., the interfacial tension, the bending moduli, or the enrichment of solvent). The understanding of these interfacial properties makes polymers suitable microscopic model systems for investigating the statistical mechanics ...

The structure of lamellar phases of symmetric AB diblock copolymers in a thin film is investigated. We quantitatively compare the composition profiles and profiles of individual segments in self-consistent field calculations with Monte Carlo simulations in the bond fluctuation model for chain length N = 32 and χN = 30. Three film thicknesses are investigated, corresponding to parallel oriented lamellae with 2 and 4 interfaces and a perpendicular oriented morphology. Taking account of capillary waves, we find good quantitative agreement between the Monte Carlo simulations and the self-consistent field calculations. However, the fluctuations of the local interfacial position are strongly suppressed by confinement and mutual interactions between lamellae.

No abstract