Rational Design of Patchy Colloids Capable of Self-Assembling into Open Crystal Lattices with Complete Photonic Bandgaps*

Patchy colloids equipped with anisotropic interactions are promising building blocks whose self-assembly provides a powerful tool for forming many complex functional materials. A main challenge in the self-assembly of patchy colloids is the design of colloidal geometry and chemistry that favor the formation of target structure thermodynamically and kinetically. We have previously developed a rational design protocol, called landscape engineering, in which we recover the free energy surface governing colloidal self-assembly process by combining molecular simulation with nonlinear dimensionality reduction technique and sculpt the free energy surface by modifying the colloidal design using genetic algorithm to make target structure thermodynamically favorable. We have applied this protocol to successfully design patchy colloids capable of self-assembling into pyrochlore lattice and cubic diamond lattice consisting of tetrahedral clusters via two-stage temperature control. Both structures are defect-free and possess complete photonic bandgaps. Our method may be extended to the rational design of self-assembling colloidal molecules and other systems such as peptides.