Block Copolymer Nanoscale Self-Assembly

This simulation models the microphase separation of A-B diblock copolymers, one of the best-understood mechanisms of nanoscale self-assembly and the basis of directed self-assembly lithography used to pattern features smaller than optical lithography can resolve. Roughly a thousand coarse-grained beads, tethered into short two-block chains, evolve under Langevin dynamics with a tunable Flory-Huggins repulsion between the unlike A and B segments. Push the segregation strength (χN) above the order-disorder threshold and the melt spontaneously organizes into periodic nanodomains; change the block volume fraction and the equilibrium morphology switches between lamellae, cylinders and spheres exactly as predicted by mean-field diblock copolymer theory, with a live order parameter tracking how segregated the melt currently is.