Microphase separation in multigraft copolymer melts studied by random-phase approximation and self-consistent field theory.

Microphase separation of AB multigraft copolymers with various numbers of graft arms per junction along the backbone was examined by the random-phase approximation and real-space implemented self-consistent field theory. The calculations carried out show that the number of graft arms per junction exerts a marked effect on the phase behavior of the multigraft copolymers. The spinodal shows an upward shift with increasing number of graft arms per junction. The order-order transitions shift toward the higher volume fraction of backbone and the ordered region becomes narrower when the number of graft arms per junction increases. The influence of the number of graft arms per junction on the domain size and the interfacial width has also been examined. It was found that the characteristic domain size decreases and the interfacial width broadens with increasing number of graft arms per junction. The theoretical results at a strong segregation were compared with the existing experimental observations and a good agreement is shown.