Multidomain Helical Nanostructure by A₁BA₂C Tetrablock Terpolymer Self-Assembly

Abstract

Among many possible nanostructures in block copolymer self-assembly, helical nanostructures are particularly important because of potential applications for heterogeneous catalysts and plasmonic materials. In this work, we investigated, via small-angle X-ray scattering and transmission electron microscopy, the morphology of a polystyrene-blockpolyisoprene-block-polystyrene-block-poly(2-vinylpyridine) (S 1 IS 2 V) tetrablock terpolymer. Very interestingly, when the volume fraction of each block was 0.685, 0.125, 0.060, and 0.130, respectively, a multidomain double-stranded helical nanostructure (MH 2 ) was formed: P2VP chains became a core helix, and PI chains formed double-stranded helices surrounding the core helix. Core and double-stranded helices are connected by short PS 2 chains, and PS 1 chains become the matrix. The experimentally observed morphology is in good agreement with the prediction by self-consistent field theory. We believe that this multidomain helical structure will be pave the way to the creation of multifunctional helical structures for various applications such as metamaterials.

Hierarchical Self-Assembly of ABC-Type Bottlebrush Copolymers

“…Indeed, the chain architecture plays an irreplaceable role in controlling the self-assembly behavior of block copolymers. ,− In the past few decades, block copolymers with different architectures have been extensively studied by experiment and theory. Novel structures were experimentally obtained from the self-assembly of architecture-engineered block copolymers. − Accordingly, these experimental results promoted theoretical studies to explore the self-assembly mechanism of these new block copolymers. − In particular, recent theoretical works have been devoted to achieving nonclassical ordered structures by purposely designing the architectures of block copolymers, ,− and great progress has been made. For example, the spherical phase region has been largely expanded by tailoring the asymmetric architectures of AB-type block copolymers, stabilizing complex Frank–Kasper spherical phases. ,− The synergistic effect of the released packing frustration and stretched bridging block has been applied to stabilize many nonclassical low-coordinated phases, such as simple cubic spheres and square cylinders .…”

Asymmetric Binary Spherical Phases Self-Assembled by Mixing AB Diblock/ABC Triblock Copolymers

“…The formation of A/C interface frustrates the chain sequence. The competition between the gain of interfacial energy and the entropy loss due to the topological constraints on the configurations leads to the formation of a lot of complex ordered phases, such as various helical phases and the knitting-pattern phase. , Furthermore, if the architecture of ABC terpolymer is changed to be more complex, their phase behaviors will be enriched further. − An interesting example is B 1 AB 2 CB 3 linear pentablock terpolymer, which is purposely designed to obtain diverse binary spherical phases with different coordination numbers (CNs) . Two prominent mechanisms are proposed to govern the transitions between these binary spherical phases; that is, the average CN and the asymmetry of CNs between A and C domains are controlled by the relative length of the middle bridging B-block and the asymmetry between the two tail B-blocks, respectively.…”