Researchers discover a hidden molecular assembly pathway that produces highly aligned soft quasicrystals over millimeter-scale regions, enabling greater control over complex material structures.
(Nanowerk News) Molecules can spontaneously organize into complex, ordered structures through a process known as self-assembly. Among these structures, soft quasicrystals are particularly fascinating because they display unusual patterns that do not repeat regularly like conventional crystals. However, producing such structures with a uniform orientation over large areas remains a major challenge.
In a recent study published in the Journal of the American Chemical Society ("Nonequilibrium Navigation of a Rugged Energy Landscape Enables the Formation of Face-On Single-Domain Dodecagonal Quasicrystals"), researchers at National Taiwan University discovered that the same molecules can follow different assembly pathways depending on temperature and molecular interactions.
By tracking how their structures changed over time, the team found that an initially formed twelvefold quasicrystal gradually transformed into different ordered structures under different conditions. These findings revealed how molecular rearrangements determine which structures eventually form.
Building on this discovery, the researchers developed a strategy called vapor-induced self-assembly (VISA) to access a normally difficult-to-reach pathway. By carefully controlling vapor treatment and cooling, they guided the molecules through a reverse structural transformation, allowing them to form highly oriented quasicrystals while suppressing the formation of competing orientations.
The result was a highly aligned soft quasicrystal extending over millimeter-scale regions, with its unusual twelvefold pattern oriented uniformly across the material. This demonstrates that controlling how molecules assemble, rather than simply what structures they form, can provide a powerful way to create complex materials with large-scale structural order.
"By exploring assembly pathways that are normally difficult to access, we can guide molecules toward highly ordered structures that conventional methods struggle to produce," says co-corresponding author Chien-Lung Wang, professor of chemistry at National Taiwan University.