Expanding the Formation Region of Double Gyroid Structures from ABC Triblock Terpolymers by Solution Casting

Self-assembled double gyroid (DG) structures derived from block copolymers have garnered significant interest due to their broad potential for material development based on the characteristics of their nanostructural morphology. This study identified an efficient process to fabricate DG structures by employing ABC triblock terpolymers and solvent casting techniques. Poly(2,2,2-trifluoroethyl methacrylate (PTFEMA)-b-styrene (PS)-b-(4-vinyl pyridine) (P4VP), referred to as FSP triblock terpolymer, was successfully synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Films derived from a chloroform (CHCl3) solution of this terpolymer were subsequently formed. The morphology in the films was characterized using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). Structural analysis revealed that the CHCl3 casting technique significantly expanded the DG region, with the volume fraction ratio of P4VP to PTFEMA (φP4VP/φPTFEMA) ranging from 0.34 to 1.70, as compared to the intrinsic range of 1.06 to 1.70. This wider composition range was attributed to the superior swelling ratio of the P4VP blocks when exposed to the CHCl3 vapor among all components of the FSP triblock terpolymer. The utilization of solvent vapor annealing proved to be an effective strategy for the rational production of advanced DG structures.