Macromolecules 1994,27, 187-192 Lamellar Phase of a Symmetric Triblock Copolymer

ABSTRACT: We study the lamellar phase formed by symmetric ABA triblock copolymers with degree of polymerization N and A monomer fraction f. Employing a mean-field, lattice formalism, we calculate the fraction of copolymers which bridge the B-rich lamellae. This fraction is found to be significant, although it is strictly bounded above by l / ~ within the formalism. Once the lamellar phase is strongly segregated, the fraction of bridges decreases slowly with increasing N, increasing Flory parameter x, and decreasing f. In the strong-segregation limit, the lamellar spacing D is found to scale as D- N0xb with a = 0.68 and b = 0.19. The interfacial width 5 does not scale as a power of N but does scale with x as 5- xc, where c =-0.51. Both D and 5 are nearly independent off. 187 1