ORDER-DISORDER-TRANSITION AND ORDER-ORDER-TRANSITION IN AB AND ABC BLOCK-COPOLYMERS - DESCRIPTION BY A SIMPLE-MODEL

Based on the description of AB-block copolymers as micellar structures given by Semenov, the phase diagram of AB-diblock copolymers is calcu lated taking the homogeneously mixed system as a reference state. The predicted value (chi N)(c)=10.385 for a symmetric AB-diblock copolymer compares very well to the result of the original Random Phase Approxi mation theory (10.495). The simplicity of the model allows its extensi on to predict order-order transitions in ABC-triblock copolymers.