  We study random copolymers consisted of two kinds of monomers with attraction
between similar kinds. The mean field analysis of this system indicates a
continuous phase transition into a phase with periodic microdomain structure.
It is shown that the inverse of the renormalized propagator has a minimum at
non-zero wave-numbers. Consequently, there is an anomalously large contribution
of fluctuations that make the disordered phase locally stable at every finite
temperature. However, below a certain temperature, the ordered phase is shown
to be locally stable and a weak first order transition is possible, similar to
the weak crystallization theory developed by Brazovskii.
