J. Phys. I France
Volume 5, Numéro 6, June 1995
|Page(s)||657 - 669|
J. Phys. I France 5 (1995) 657-669
Glass Transition Versus Microphase Separation: a Phenomenological Replica-Field Theory for AB Copolymer SystemsAndrey V. Dobrynin
Department of Physics and Astronomy, University of Rochester, Rochester, New York 146270011, U.S.A.
(Received 3 August 1994, revised 29 November 1994, accepted 16 February 1995)
We present a phenomenological replica-field theory for symmetric AB copolymer systems with the A-block near its glass transition point. Using a variational principle based on the second Legendre transformation we prove that the interaction between composition fluctuations, due to the loss mobility of the A monomers, results in the elimination of microphase separation. Instead of a microphase separation there is a third-order phase transition between the homogeneous state and a glass-like state with broken replica symmetry of the two-replica density-density correlation function. We show that near the point of the glass transition two-replica correlation function is proportional to the square of the one-replica correlation function , where is a matrix describing the metric properties of the replica space. The phase diagram for this class of copolymer systems is calculated.
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