Summary: A novel method has been successfully developed to prepare binary blends of PS and MCPA6. The blends are formed by the radical polymerization of styrene in CL, followed by the in‐situ anionic ring‐opening polymerization of CL in the presence of PS. The phase morphology investigated using SEM reveals that PS/MCPA6 blends with a PS content of 10 wt.‐% or lower consists of a MCPA6 matrix and a dispersed PS minor phase. Remarkably, phase inversion occurs in blends that have a PS content of 15 wt.‐% or higher, in which MCPA6 is no longer continuous but finely dispersed in the PS continuous phase. The phase inversion occurs at an extremely low PS content, and this phenomenon is unusual for traditional polymer blends prepared by melt blending. The probable reason for the particular phase morphology development is explained. The stability of the phase morphologies of the PS/MCPA6 blends after annealing at 250 °C is also investigated by SEM.
SEM micrograph of the fractured surface of a PS/MCPA6 blend with a PS content of 20 wt.‐%, in which MCPA6, as spherical particles, is dispersed in the PS continuous phase.
