Self-assembly of rod-coil-rod triblock copolymers: A route toward hierarchical liquid crystalline structures

Brownian dynamics simulations are performed to investigate self-assembly behavior of rod-coil-rod triblock copolymers that contain two types of rod blocks. These rod-coil-rod triblock copolymers are capable of self-assembling into liquid crystalline (LC) structures with hierarchy. The morphologies of the hierarchical LC structures can be controlled by temperature, symmetry of LC blocks, and block length. As the temperature decreases, a transition from isotropic lamellae to smectic C lamellae is observed, accompanied by an increase in orientational ordering and tilt angle of rod blocks. For the hierarchical lamellae-in-lamella structures formed by symmetric block copolymers, there are two LC phases with nearly identical ordering and tilt angle for two rod blocks. While for the lamellae-in-lamellae formed by asymmetric block copolymers, the two LC phases exhibit two different length scales with diverse ordering degrees and tilt angles. By adjusting the lengths of coil and rod blocks, the stability regions of the structures are mapped out in space of the block length versus the temperature. The findings in the present work could provide useful information for understanding the self-assembly behavior of rod-coil-rod triblock copolymers and designing hierarchical liquid crystalline structures. (C) 2016 Elsevier Ltd. All rights reserved.