Fabrication of effect pigments with full visible photonic crystal colors via the shear-induced assembly of multinary colloidal nanoparticles†

Shear-induced assembly technique offers unprecedented scalability in the preparation of versatile photonic crystal materials. Herein, different-sized colloidal nanoparticles were placed within a multicomponent blending system for effective shear co-assembly to enable precise tuning of the photonic band gap and structural colors across the whole visible spectrum of light. The obtained equilibrium structures, such as the crystalline or amorphous states, could be well traded-off for various optical appearances by varying the relative ratios of the blends. A coefficient of variation (CV) value less than 0.3 is crucial to balance strain energy during the cooperative working assembly for manipulating complex functional spatial nanostructures with greatly reduced requirements of colloidal monodispersity. The resultant photonic materials could be further processed into diverse effect pigments with customized and selective optical performances for alternative colorants. This work provides valuable insights into predicting specific visible spectral wavelengths and optical characteristics by controlling photonic nanoarrays through a simple modulation of the composition of multivariate blends.