Entropically driven phase separation and effective multibody interactions in block copolymers.

The need for effective multibody interactions is asserted in understanding the entropically driven phase separation of diblock copolymers, arising from disparity in self cohesion and association between dissimilar components. Through Landau analysis combined with a molecular equation of state to describe associability, it is demonstrated that diblock copolymers can exhibit dual critical points. We highlight the significance of multibody effects in correctly locating these critical points. Additionally, a region of first-order transition beyond the ϕ^{4} Landau framework is identified, which is further examined using a companion self-consistent field theory.