Hierarchical Self-Assembly of ABC-Type Bottlebrush Copolymers

Abstract

We have performed dissipative particle dynamics simulations to study the self-assembly of ABC-type bottlebrush copolymers (BBCPs), one portion of whose backbone is grafted by pairs of A-blocks and the other portion is grafted by B/C-blocks in pairs, focusing on the effects of the number of A side chains, the length of B side chains relative to that of C side chains, and the rigidity of the backbone on the formation of hierarchical structures. A number of hierarchical structures with the superstructures formed by the phase separation between A and B/C-blocks and the substructures formed by the phase separation between B and Cblocks are observed. Some hierarchical structures are similar to those self-assembled by ABC star copolymers, whereas their stable parameter regions of ABC-type BBCPs are much larger. On the other hand, the ABC-type BBCPs can also form some novel hierarchical structures that are hard to form in ABC star copolymers. Though the formation of the A-superstructure and the B-substructure in many hierarchical structures can be independently controlled, there are also some hierarchical structures in which the transitions of the superstructure and substructures are coupled. In other words, the A-superstructure changes along with the transformation of the B-substructure for fixed f A . In addition, our results demonstrate that the rigidity of the backbone has a significant effect on the formation of the hierarchical structure in ABC-type BBCPs, i.e., a rigid backbone favors the normal arrangement of B-substructures to A-superstructures. Our work not only deepens the understanding of the self-assembly mechanism of ABC-type BBCPs but also provides helpful guidance for experiments to fabricate interesting hierarchical structures.

Hierarchically Structured Nanocomposites via Mixed-Graft Block Copolymer Templating: Achieving Controlled Nanostructure and Functionality

“…At a larger scale, the phase separation between PS and the PEO­(PTA)- co -PE cylinders resulted in the HCP superstructures. To our knowledge, this unique HPC- in -HPC was experimentally visualized for the first time and differed from the CYL- out -CYL structures previously reported in the neat (A- co -B)- b -C mGBCP self-assembly, where the A-cylinders were positioned within the continuous phase of superstructures and aligned either perpendicular to the surface of C-cylinders or radiating outward from each C-cylinder . The addition of PTAs into the PEO domains may render the HPC- in -HPC structure in a stable state (Figures S17–18), as detained by the strong interaction between PTA and PEO segments.…”

Architectural Design of Block Copolymers

“…If the bridging block is acted by a bottlebrush architecture, the introduced rigidity will increase the fraction of bridging configuration drastically. Moreover, if a bottlebrush block is connected to a linear block of different chemical component, it will amplify the effect of spontaneous curvature toward the linear block due to their architectural asymmetry. , In fact, with the advances in the synthesis methods of bottlebrush polymers, novel bottlebrush architectures including dumbbell-shaped, cone-shaped, and block miktobrushes have been synthesized, providing highly designable architectures for the bottlebrush block copolymers. − Recent experimental and simulation studies have shown that when the molecular parameters, such as grafting densities, side-chain lengths, and molecular shapes, are appropriately designed, kinds of structures including complex networked and hierarchical structures, can be obtained. − With high degree in the designability of bottlebrush, more novel self-assembly structures may be obtained in the future. More specifically, if an architecture is designed to enable the various sophisticated mechanisms simultaneously, either AB-type or ABC-type block copolymers will exhibit more unpredictable self-assembly behaviors.…”

“…There are some other important architectures that have attracted increasing attention but are rarely introduced into the purpose design of architectures, such as bottlebrush and cyclic block copolymers. For the bottlebrush block copolymers, one of the most appealing aspects is their ability to form ordered structures with domain size approaching hundreds of nanometers, which is hardly affordable for the conventional block copolymers, making them ideal for the fabrication of photonic crystals. , Many experimental and theoretical works have demonstrated that bottlebrush block copolymers exhibit unique self-assembly behaviors. − One of the remarkable features influencing the self-assembly for the bottlebrush architecture lies in the rigidity of the backbone induced by the dense grafting of side chains. If the bridging block is acted by a bottlebrush architecture, the introduced rigidity will increase the fraction of bridging configuration drastically.…”

Directed Self-Assembly by Sparsely Prepatterned Substrates with Self-Responsive Polymer Brushes

“…Because the morphologies are difficult to identify clearly from instantaneous configurations due to thermal fluctuations, we calculate the local concentration by taking the time average on the instantaneous configurations of bead positions within one short period where the morphology does not change notably, using the method proposed previously …”