COPOLYMER MELTS IN DISORDERED MEDIA

We have considered a symmetric AB block copolymer melt in a gel matrix with preferential adsorption of A monomers on the gel. Near the point of the microphase separation transition such a system can be describe d by the random held Landau-Brazovskii model, where randomness is buil t into the system during the polymerization of the gel matrix. By usin g the technique of the 2-nd Legendre transform, the phase diagram of t he system is calculated. We found that preferential adsorption of the copolymer on the gel results in three effects: a) it decreases the tem perature of the first order phase transition between disordered and or dered phase; b) there exists a region on the phase diagram at some sma ll but finite value of the adsorption energy in which the replica symm etric solution for two replica correlation functions is unstable with respect to replica symmetry breaking; we interpret this state as a gla ssy state and calculate a spinodal Line for this transition; c) we als o consider the stability of the lamellar phase and suggest that the lo ng range order is always destroyed by weak randomness.