Flow-accessible gyroid phases in block copolymer melts through 3D printing

Gyroid phases in block copolymers form continuous 3D networks that enable efficient ion and electron transport, unique optical properties, and high surface area for membranes and catalytic systems. However, their stability window in the classical phase diagram is narrow, making them difficult to achieve through composition control alone. Here, we show that a widely available block copolymer polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS, 80% diblock and 20% triblock) can form an oriented gyroid via non-equilibrium processing. Using 3D printing with controlled thermal history, we identify a processing pathway whereby a flow-oriented cylindrical phase transforms into hexagonally perforated lamellae upon annealing, and subsequently into a gyroid upon controlled cooling rates. This work highlights the role that non-equilibrium processing (here in the form of 3D printing) can play in selecting and controlling both the local- and long-range structure of block copolymers.