Investigation of Fluctuation Effects in Diblock Copolymer and homopolymer mixture through Langevin Field Theoretic Simulation

Abstract

In the polymer community, it is well known that Block Copolymer (BCP) melts can form microphases at a sufficiently high χN, and related research is actively pursued. Researchers have put considerable effort into controlling this phenomenon, and blending random copolymers (RCPs) or homopolymers (HPs) is one of those strategies. Under experimental conditions, a BCP melt usually forms a randomly directed lamellar structure referred to as the "Fingerprint pattern." Mixing short RCPs or HPs into the BCP melts often helps the system gradually achieve long-range ordered microstructures. Theoretically, Self-Consistent Field Theory (SCFT) has demonstrated such a possibility by reducing the energy barrier for the removal of defects. However, due to the limitations of the SCFT, which is based on mean-field theory, the consideration of fluctuation effects that help the system escape from metastable states has been lacking. Consequently, theoretical methods that overcome this limitation of the SCFT method have been developed, and Langevin Field Theoretic Simulation (L-FTS) is one of them. In this study, we employ L-FTS, a method known to incorporate fluctuation effects into the polymer field theory, to investigate the influence of fluctuations when mixing RCPs or HPs into BCP melts. In particular, we explore the shift of the order-to-disorder transition point by comparing the results of SCFT and FTS.