Self-assembly in rod/coil block copolymers: Degenerate behavior under nonconfinement

Abstract

The self-assembly of block copolymers containing rigid blocks have received abiding attention due to its rich phase behavior and potential for use in a variety of applications. In this work, under asymmetric interactions between rod/coil components, the self-assembly of coil/coil/rod ABC triblock copolymers is studied using selfconsistent field of lattice model. In addition to micelles, centrosymmetric lamellae (CSLM), lamellae, perforated lamellae, strips and gyroids, non-centrosymmetric (NCSLM) lamellae and wavy morphologies are observed as stable phases. The phase diagram of interaction between rod and coil components versus the rod fraction is constructed given a fixed interaction between coil components. For intermediate rod fraction, degenerate behavior is observed. NCSLM and CSLM are degenerate structures. It is found that the entropy of chain conformation plays an important role for this rich behavior. A mechanism of the degenerate behavior is proposed in coil/rod block copolymers under noncofinement. This study provides some new insights into the degenerate behavior of block compolymers, which can offer a theoretical reference for related experiments.

Liquid-Crystal Ordering and Microphase Separation in the Lamellar Phase of Rod-Coil-Rod Triblock Copolymers. Molecular Theory and Computer Simulations

“…As a result, the existing theory of rod-coil triblock copolymers employs a crude lattice model and does not take into consideration the orientational interaction between rigid fragments. The theory also does not describe the orientational ordering in rod-coil triblock copolymers [ 33 ]. Solution-based systems containing copolymers with rod-like blocks demonstrate even more complex behavior which stimulates using simplified scaling approaches [ 34 ].…”

Different Mechanisms of Translational Symmetry Breaking in Liquid-Crystal Coil–Rod–Coil Triblock Copolymers

“…One notes that in the system of long chains with rigid rod fragments characterized by both orientational and translational degrees of freedom, the SCFT theory remains computationally challenging even taking into account recently developed novel numerical algorithms [27,38]. This may explain why the existing theory of rod-coil triblock copolymers [39,40] does not account for the orientational interaction between rigid rod segments and their orientational ordering.…”