On and Off Deformability of Supramolecular Micelles in the Soft Frank-Kasper σ Phase.

Deformability is a key pathway to structural complexity in self-assembled systems. Although numerous molecular systems have been engineered to form Frank-Kasper (FK) phases, they typically rely on size- or shape-based asymmetries rather than new structural degrees of freedom. By incorporating chain-length asymmetry into dendritic amphiphiles, this study endows supramolecular micelles in the soft FK σ phase with a controllable deformability. The asymmetric dendrons (ADs) form anisotropic σ phases with domain-dependent diffraction patterns caused by micelle deformation, as verified by the anisotropic Debye-Waller simulations. Over time, these anisotropic micelles reorganize along specific planes, triggering a σ-to-lamellar transition. Incorporating hydrophobic guest molecules compensates for the chain-length asymmetry, switching off deformability and restoring isotropic packing. Thus, deformability emerges as a tunable parameter governing lattice symmetry and phase evolution, offering a design principle for scalable and hierarchically complex assemblies.