Abstract
Previous theories describing the phase behavior of copolymer blends have ignored the sequence distribution of monomer units in the copolymer.We introduce a parameter, that describes the binary sequence distribution of the monomers in acopolymer chain.By varying, we can describe a block,random,or alternating copolymer.It is assumed that the interaction energy between amonomer of homopolymer Candthemonomer A(orB) in the copolymer AB is mediated by the nearest neighbors chemically bonded to the A(orB) structural unit. It is found that the sequence distribution may significantly affect the degree of compatibility between the polymers AB and C.For a fixed composition,there is an optimal range of values(or sequence distributions) for which the C/AB systemismiscible.