Simulation of phase separation in melts of regular and random multiblock copolymers

Abstract

The dissipative particle dynamics method and parallel computing are employed for computer simulation of phase separation in melts of regular and random (Markovian) AB multiblock copolymers of symmetric compositions. For the first time, it is shown that, as the Flory-Huggins parameter χ is increased, lamellar microstructures are formed in all these systems. At preset block length M, the microstructures arise in regular copolymers at lower χ values than those in random copolymers, while the formed lamellas are narrower and have smaller amounts of defects. At χM > 100, a superstrong segregation regime develops in the regular copolymers. In random copolymer melts, bicontinuous structures are observed for a long time; in the long run, they are likewise transformed into lamellar structures whose imperfection substantially increases with M.