Fluctuation correction for the order-disorder transition of diblock copolymer melts

The order-disorder transition (ODT) of diblock copolymer melts is evaluated for an invariant polymerization index of (N) over bar =10(4), using field-theoretic simulations (FTS) supplemented by a partial saddle-point approximation for incompressibility. For computational efficiency, the FTS are performed using the discrete Gaussian-chain model, and results are then mapped onto the continuous model using a linear approximation for the Flory-Huggins chi parameter. Particular attention is paid to the complex phase window. Results are found to be consistent with the well-established understanding that the gyroid phase extends down to the ODT. Furthermore, our simulations are the first to predict that the Fddd phase survives fluctuation effects, consistent with experiments.

Automated summary

The order-disorder transition of diblock copolymer melts was evaluated using field-theoretic simulations for an invariant polymerization index, with particular focus on the complex phase window. The results support the understanding that the gyroid phase extends down to the ODT, and predict that the Fddd phase can survive fluctuation effects, which is consistent with experimental findings.