Enlarged Phase Regions of Multi-Continuous 3D Network Nanostructures in ABC Triblock Copolymers

Aiming to increase the stability region of three-dimensional (3D) multi-continuous morphologies due to great potential application in smart sensors, gas separation membranes, and photonic materials, in this paper, we control the block ratio of different channels of an ABC triblock copolymer according to the curvature of these multi-continuous nanostructures. In the small A volume fraction region, the multi-continuous gyroid nanostructure is stable when f_B/f_C equals 1/3, while two-domain lamellae (L_B/C) and three-layer lamellae (L₃) are obtained when B and C blocks have comparable volume fractions, suggesting that changing the f_B/f_C ratio is an effective way of forming multi-continuous polymer network nanostructures. Interestingly, a large phase region of the core-shell gyroid and O⁷⁰ are found under the condition of f_B/f_C = 4. The mechanism of changing the ratio to enlarge the phase regimes of multi-continuous nanostructures can be ascribed to the existence of curvature in gyroid and O⁷⁰ nanostructures. Therefore, the formed thin layer must be consistent with these curvatures, which can be tuned by the adjustment of the block ratio. The proposed mechanism and the calculated phase diagram can effectively guide the experimental observation of these multi-continuous nanostructures.