Core–Shell Double Gyroids Directed by Selective Solvation for ABC Triblock Terpolymers

The formation of ABC triblock terpolymers through solution casting is still challenging. In this study, core–shell double gyroid network structures are fabricated via solution casting using poly(2,2,2‐trifluoroethyl methacrylate) (PTFEMA) (F)‐ b ‐[poly(4‐vinylpyridine) (P4VP) (P)]‐ b ‐[polystyrene (PS) (S)] (FPS) triblock terpolymers in N,N ‐dimethylformamide (DMF). Upon heat treatment, the polymer tends to form a sphere‐in‐lamellar structure at the F/S interface. Given the solubility properties of each component in DMF, it is anticipated that the effective volume fraction of F relative to P would increase in concentrated solutions and the effective volume fraction of S would decrease. The microphase‐separated structure derived from the DMF solution consistently results in the formation of a network structure composed of a core–shell double gyroid, with F as the matrix, P as the shell, and S as the core, and their periodic lengths gradually increase to 110.8, 131.8, and 162.7 nm as increase molecular weights of PS blocks to 13.8, 20.7, and 28.8 kg mol −1 . Based on the solubility properties of the polymer components highlighted in this study, the solvent selection strategy is broadly applicable to ABC triblock terpolymers featuring various polymer components, offering a more efficient avenue for fabricating core–shell double gyroid structures.