Diblock Copolymer Melt in an Electric Field: Stability of the Homogeneous State in the Random Phase Approximation

The contribution of I.Ya. Erukhimovich (1947-2022) to the creation of the theory of microphase separation in di- and triblock copolymers has been briefly analyzed. His matrix method of calculating correlation functions for multicomponent polymer systems has been applied to find the spinodal of a diblock copolymer melt in a static electric field. It has been strictly shown that for a linear dependence of local dielectric constant of the copolymer on the order parameter the spinodal condition remains the same as in the absence of the electric field. The correction to the critical value of the Flory-Huggins parameter has been calculated for more general case of the quadratic dependence.