Dissipative particle dynamics simulation study on the mechanisms of self-assembly of large multimolecular micelles from amphiphilic dendritic multiarm copolymers

Dendritic multiarm copolymers, including dendrimer multiarm copolymers and hyperbranched multiarm copolymers, have shown great potential to be excellent precursors in self-assembly, and many impressive supramolecular structures have been prepared through the solution self-assembly of them. However, the corresponding theoretical studies on the self-assembly mechanism have been greatly lagging behind. Herein, we report the micellization behaviors of amphiphilic dendritic multiarm copolymers with a hydrophobic dendritic core and many hydrophilic arms by dissipative particle dynamics simulations. Both the self-assembly mechanisms and the dynamic self-assembly processes for the formation of unimolecular micelles, microphase-separated small micelles, and large multimolecular micelles have been disclosed through the simulations. Most importantly, the work has proved the large multimolecular micelles are a kind of multimicelle aggregate (MMA) with two formation mechanisms. One is called the unimolecular micelle aggregate (UMA) mechanism, which describes the formation of large multimolecular micelles from direct aggregation of unimolecular micelles; the other is called the small micelle aggregate (SMA) mechanism, which shows that the dendritic multiarm copolymers first self-assemble into small micelles and then the small micelles further aggregate into large multimolecular micelles. In addition, the microphase separation model of the dendritic multiarm copolymers as well as the effects on the formations of UMAs and SMAs are also discussed. These simulation results agree well with experimental observations, and have extended the understanding of the micellization process of dendritic multiarm copolymers.