Mosaic two-lengthscale quasicrystals

T. Dotera, T. Oshiro & P. Ziherl

Nature 506, 208–211 (2014).



Over the past decade, quasicrystalline order has been observed in many soft-matter systems: in dendritic micelles, in star and tetrablock terpolymer melts and in diblock copolymer and surfactant micelles. The formation of quasicrystals from such a broad range of 'soft' macromolecular micelles suggests that they assemble by a generic mechanism rather than being dependent on the specific chemistry of each system. Indeed, micellar softness has been postulated and shown to lead to quasicrystalline order. Here we theoretically explore this link by studying two-dimensional hard disks decorated with step- like square-shoulder repulsion that mimics, for example, the soft alkyl shell around the aromatic core in dendritic micelles. We find a family of quasicrystals with 10-, 12-, 18- and 24-fold bond orientational order which originate from mosaics of equilateral and isosceles triangles formed by particles arranged core-to-core and shoulder-to-shoulder. The pair interaction responsible for these phases highlights the role of local packing geometry in generating quasicrystallinity in soft matter, complementing the principles that lead to quasicrystal forma- tion in hard tetrahedra. Based on simple interparticle potentials, quasicrystalline mosaics may well find use in diverse applications ranging from improved image reproduction to advanced photonic materials.

Editor's summary

The unusual non-periodic ordering that defines a quasicrystal has been found in a range of very different material systems, yet the origins of such ordering remain somewhat enigmatic. Tomonari Dotera et al. turn their attention to so-called 'soft-matter' systems, such as fuzzy dendritic micelles. Through a serious of simulations of a two-dimensional model system, the authors identify the local interactions that appear to be responsible for the formation of quasicrystals in these systems.