LAMELLAE AT A PREFERENTIAL WALL

The profile of the interfacial plane of a diblock copolymer layer in i ts lamellar melt phase when it is brought into contact with a hard, sm ooth substrate is calculated. The chains are in the strong-stretching limit. Far from the substrate, the planes are perpendicular to the sub strate, and they become distorted near it by a small wetting preferenc e for one of the components of the copolymer. The profile of the disto rtion is calculated in an Alexander model by making an analogy to the steady flow of an incompressible fluid. The contact angle between the two components of the copolymer and the substrate is the same as it wo uld be if the blocks were not joined to make diblock copolymers. The a pproach to this contact angle is characterized by a singularity which is calculated. For any molecular weight and elasticity asymmetry betwe en the components of the copolymer, the curvature of the interface cha nges sign contrary to the case of the interface between two simple liq uids. For most values of asymmetry, the interface is an exponentially damped oscillation. (C) 1996 American Institute of Physics.