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.
Highlights
Block copolymers are macromolecules composed of chemically distinct subchains or blocks
The phase diagrams for copolymers constructed by fA versus χN are shown in figure 2 for fB = 0.2, 0.4, 0.6, and most of the regions of all the phase diagrams are occupied by lamellar phase
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
Summary
Block copolymers are macromolecules composed of chemically distinct subchains or blocks. Woloszczuk et al employed on-lattice Monte Carlo simulations to examine the phase behavior of molecularly flexible asymmetric ABA copolymers in the limit of superstrong segregation, wherein interstitial micelles composed of the minority A endblock were observed to arrange into two-dimensional hexagonal arrays along the midplane of B-rich lamellae These studies have demonstrated that molecular asymmetry is an important factor for self-assembly of block copolymers. In this work, using SCFT lattice model, we concentrate on the effect of the volume fraction of the coil block on structure transition in the ABC coil-rod-coil triblock copolymers, providing for different rod block fractions.
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