The effect of asymmetry of the coil block on self-assembly in ABC coil-rod-coil triblock copolymers

TL;DR

This study uses the self-consistent field approach to explore how coil block asymmetry influences microphase separation in ABC coil-rod-coil triblock copolymers, revealing various stable structures and phase behaviors.

Contribution

It provides new insights into the impact of coil block asymmetry on self-assembly in ABC coil-rod-coil triblock copolymers, including phase diagrams and structure transitions.

Findings

Different stable structures observed: lamellae, cylinders, gyroid, core-shell hexagonal.

Effect of coil block fraction depends on rod block fraction.

Asymmetry effects vary with the fraction of the rod block and interaction parameters.

Abstract

Using the self-consistent field approach, the effect of asymmetry of the coil block on the microphase separation is focused in ABC coil-rod-coil triblock copolymers. For different fractions of the rod block $f_{\text B}$, some stable structures are observed, i.e., lamellae, cylinders, gyroid, and core-shell hexagonal lattice, and the phase diagrams are constructed. The calculated results show that the effect of the coil block fraction $f_{\text A}$ is dependent on $f_{\text B}$. When $f_{\text B}=0.2$, the effect of asymmetry of the coil block is similar to that of the ABC flexible triblock copolymers; When $f_{\text B}=0.4$, the self-assembly of ABC coil-rod-coil triblock copolymers behaves like rod-coil diblock copolymers under some condition. When $f_{\text B}$ continues to increase, the effect of asymmetry of the coil block reduces. For $f_{\text B}=0.4$, under the symmetrical and rather asymmetrical conditions, an increase in the interaction parameter between different components leads to different transitions between cylinders and lamellae. The results indicate some remarkable effect of the chain architecture on self-assembly, and can provide the guidance for the design and synthesis of copolymer materials.