POLYDISPERSITY EFFECTS ON THE MICROPHASE-SEPARATION TRANSITION IN BLOCK COPOLYMERS

The influence of polydispersity on the transitions occurring in the weak segregation regime and on the scattering functions of the disordered phase in diblock copolymers is studied for one-component and multicomponent systems including mixtures with homopolymers. Application of the fluctuation corrections given by Fredrickson and Helfand9 leads to the determination of the transition windows as a function of degree of polymerization N, polydispersity U, and composition f. The applicability of the fluctuation corrections appears to be extended to lower N and f with increasing U. The prediction of transitions is facilitated by the concept of a reduced phase diagram. © 1990, American Chemical Society. All rights reserved.