I will describe some mathematical features of a variational model for the description of micro-phase separation in di-block copolymer melts. In dimension one, minimizes of this energy functional present periodic patterns on a certain microscopic scale. In higher dimension, however, very little is known on the structure of minimizers. In a joint work with R. Choksi and F. Otto we have proved a uniform energy bound (on the right microscopic scale), and shown that the admissible patterns should arise as local minimizer on the entire space of the unscaled functional.