Elastic properties of a diblock copolymer monolayer and their relevance to bicontinuous microemulsion

A new self-consistent field theory (SCFT) method is introduced for evaluating the exact mean-field elastic properties of a diblock copolymer monolayer separating two immiscible homopolymer phases. The method is illustrated on ternary blends of A- and B-type homopolymers of equal size blended with AB diblock copolymers of symmetric composition. We make comparisons with weak- and strong-segregation calculations, as well as with an earlier less accurate SCFT-based calculation. These previous approaches are found to produce sizable degrees of inaccuracy, emphasizing the need for our improved method. To conclude, we address the significance of our calculation in the efforts to develop bicontinuous polymeric microemulsions. Our primary conclusion is that the molecular weight of the diblock copolymer must be small. (C) 1999 American Institute of Physics. [S0021-9606(99)50608-9].