Dissipative Particle Dynamics Study of Order−Order Phase Transition of BCC, HPC, OBDD, and LAM Structures of the Poly(styrene)−Poly(isoprene) Diblock Copolymer

Abstract

A Gaussian chain model of poly (styrene)−poly (isoprene) (PS−PI) block copolymer with a dissipative particle dynamics (DPD) simulation was employed to study the formation of specific characteristic structures such as body-centered-cubic (BCC), hexagonal packed cylinders (HPC), ordered bicontinuous double diamond (OBDD), and lamellar (LAM) via order−disorder transition (ODT). The BCC, HPC, OBDD and LAM microphases were then subjected to thermal cycles of heating and cooling. The order−order phase transition (OOT) from HPC to BCC was monitored and two new transitions, OBDD to LAM and LAM to hexagonal perforated layers (HPL), were detected during the thermal process. Two metastable states (cylinders and HPL) were observed in the OOT process from the OBDD to LAM microphases. It is shown that all order−order transitions between the different kinds of structures are thermoreversible. The results were compared with the predictions of recent theories and with available experimental outcomes and thus provide a tes...