Self-assembly of ABC dendrimer by real-space self-consistent mean field theory in a two-dimensional space

Abstract

Microphases and triangle phase diagrams of ABC dendrimers with different chain lengths of the second generation are investigated by a real-space implementation of self-consistent mean field theory in a two-dimensional (2D) space. Seven main stable ordered morphologies have been observed in the intermediate-segregation regime, including “three-color” lamellae phase (LAM₃), “three-color” hexagonal honeycomb phase (HEX₃), dodecagon-hexagon-tetragon phase (DOHT), octagon-octagon-tetragon phase (OOT), lamellae phase with alternating beads (LAM + AB), decagon-hexagon-tetragon and decagon-hexagon-hexagon phase ([DEHT;DEHH]), and core-shell hexagonal lattice phase (CSH). Simulation experiments reveal that when the volume fractions of three different polymer block species are comparable, the dendritic molecular architecture of the polymer chain has a strong topological constraint on the geometry of microphases. In a particular range of volume fractions f_a ≈ f_b ≈ f_c, the HEX₃ phase is found to be the most stable. In addition, near the region of HEX₃ in the triangle phase diagrams, another competitive microphase (OOT) has an energy which is close to HEX₃ was found to be stable as well. However, when the volume fraction of one block species is big enough, such as f_a (or f_b, f_c) ≥ 0.7, especially in the system of ABC dendrimer with equivalent block chain of the second generation and asymmetric interaction parameters, the influence of dendritic architecture on the morphologies is not so obvious. If the chain topology of the dendrimer does not stretch sufficiently, then it displays a LAM + AB microphase as linear ABC terpolymer.