Formation of Single Gyroid Nanostructure by Order–Order Phase Transition Path in ABC Triblock Terpolymers

The kinetics for the formation of the single gyroid (SG) nanostructure in ABC triblock terpolymers is investigated using the self‐consistent field theory combined with the string method. Both simple phases (lamellae, cylinders, and spheres) and networked double diamonds (DD) can transform into SG through order–order phase transition (OOT). In particular, a packing frustration‐induced variation in the epitaxial relationship between DD and SG is demonstrated. By regulating the block interaction, an expected epitaxial phase transition between these two networks without any rotation of the crystallographic directions can be achieved. Interestingly, the hexagonally perforated lamellae (HPL) are encountered in all identified transition pathways to SG. Nucleation kinetics investigation shows that the HPL tends to nucleate from SG easily, which confirms the kinetic origins of the instability of SG in experiments. Therefore, several strategies of preventing the SG being bypassed, such as controlling annealing time and rates during the morphology evolution, are proposed to promote the stabilizing of the SG in kinetic pathways. The findings reported here provide a novel route for fabrication of SG structured materials by manipulating both the epitaxial relationship and the nucleation kinetics in OOT pathways.