Expanding volume asymmetry in unary systems via cyclodextrin-based giant molecules

Symmetry breaking underlies a wide range of emergent physical properties. In unary systems, maintaining a large volume asymmetry among self-assembled micelles (‘mesoatoms’) is yet intrinsically difficult, because mesoatomic sizes tend to homogenize as the system approaching thermodynamic equilibrium. Here, we exploit cyclodextrin ( CD ) as a molecular scaffold and discover the unprecedented coexistence of one- and two-molecular mesoatoms in a unary αCD-OP 18 system, achieving an ultrahigh volume ratio, V L /V S ≈ 2, and stabilizing a low-symmetry C14 Frank-Kasper phase. Theoretical analysis reveals that this coexistence, arising from the optimal number of peripheral OPOSS cages and the integer constraint on the number of molecules per mesoatom, amplifies mesoatomic volume asymmetry. These findings demonstrate that the volume asymmetry of unary systems can be further enhanced, thereby enabling controlled symmetry breaking and facilitating the formation of low-symmetry soft-matter phases. Table-of-Contents: Coexistence of one- and two-molecular mesoatoms of αCD-OP 18 drives large volume asymmetry ( V L /V S ≈ 2) and C14 phase formation. μ S and μ L are the number of molecules per small and large mesoatom.