Architectural Design of Block Copolymers

Abstract

Highly designable architectures of polymers endow the same polymer with different properties. In principle, diverse architectures should enrich the self-assembly behavior of block copolymers, providing a possibility for the formation of many novel ordered phases. However, it is infeasible to simply search the huge library of architectures for the formation of desired new phases, and it requires some valid guiding principles for efficiently designing block copolymers. In the past decade, some sophisticated mechanisms have been proposed in addition to the common mechanism that the self-assembly of block copolymers is dictated by the competition between the interaction energy and the stretching energy. To realize these sophisticated mechanisms in the architectures constitutes the guiding principles for the design of block copolymers. A series of theoretical works have demonstrated that one or more sophisticated mechanisms can be derived for desired novel phases, and thus the architectures of block copolymers can be properly designed to achieve these phases. To date, only the architectures of flexible copolymers are considered. In the future, the concept of designing architectures for the formation of the desired novel phases can be extended to a broader range of block copolymers, e.g., semiflexible and charged. In addition, it would be more useful to design block copolymers for the desired properties that are dictated by not only the chain architecture but also the phase-separated structure.

Largely Asymmetric Binary Mesocrystals beyond Inorganic Crystals Formed in Linear ABC/ABC Blends

“…For example, experiments have observed a cubic AB 8 binary nanocrystal belonging to the Fm 3̅ m space group; yet no corresponding prototype has been identified in inorganic crystals. , Cheng et al have utilized giant surfactants to self-assemble into a series of low-symmetry Frank–Kasper phases, for example, the σ, A15, C14, C15, Z phase, and a sixth Frank–Kasper μ phase . In particular, very recently, they discovered the Frank–Kasper ϕ phase that has no prototype of inorganic crystal. , Due to largely designable architectures, block copolymers become a unique class of self-assembly units, − providing unparalleled opportunities for the preparation of mesocrystals. − In particular, the arrangement of the spherical micelles assembled by block copolymers often resembles the periodic lattices of inorganic crystals.…”

Automated Search Strategy for Novel Ordered Structures of Block Copolymers

“…Moreover, self-assembly has become one of the most important means for human beings to prepare nanostructured materials . Block copolymers provide a unique class of self-assembly systems due to their rich phase behavior and flexible architecture designability. ,− In addition to the globally stable structure, the complex free energy landscape of BCP self-assembly contains numerous local minima corresponding to metastable structures. For a given BCP system, a prerequisite for theory to identify the stable structure is that the main metastable structures competing with it must be found.…”