The effect of thermodynamic fluctuations on the formation of superstructures in random heteropolymers

The behavior of a random AB block copolymer with the same fraction of monomers of each type near the critical point has been studied. In the Brazovskii approximation it is shown that thermodynamic fluctuations give rise to a lamellar structure whose period is greater than the size of a block. The structure appears as a result of a first-order phase transition. The parameters of this transition are calculated and the region of coexistence of the disordered and lamellar phases is found. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 3, 183–187 (10 August 1996)