A Brownian Dynamics Simulation Study On Hierarchical Self-assembly Of Patchy Particles In Dilute Solution

Patchy particles usually consist of more than one different regions withdiverse shapes, positions, chemical functionalities and electrical properties. Dueto specific interactions between different pattens, they often self-assemble intoordered structures which have numerous potential applications in many fields,such as photonic crystals, drug delivery, date storage and barcoding. In order tomake the self-assembly structures of patchy particles have a better application, itis necessary to understand the self-assembly process of patchy particles. In thisstudy, Brownian dynamics simulation method has been used to investigate theself-assembly behavior of ABA and ACB triblock patchy particles.We study the self-assembly behavior of two-patch particles with D∞hsymmetry by using Brownian dynamics simulations. The self-assemblyprocesses of two-patch particles with diverse patch coverage in two selectivesolvent conditions are investigated. The patchy particles form linear thread-likestructures with low patch coverage in a solvent that is bad for patches but goodfor matrix, whereas they form three-dimensional network structures withrelatively high patch coverage on surface. For patchy particles in a solvent thatis good for patches but bad for matrix, monolayer structures are obtained at highpatch coverage, and only cluster structures emerge when surface patch coverageis low.Hierarchical self-assembly provides a more precise control to optimizeordered structure quadratically. In recent years, the hierarchical self-assemblymethods are used to study the complex stuctures and excellent propertiesderived from the polypeptide, block copolymer, nanoparticles and colloidalparticles. We investigate the hierarchical self-assembly of ACB triblock patchyparticles, where the self-assembly product of first stage is set as the initialstructure for the second stage self-assembly. Hierarchical assembly offers apromising route that allows to fabricate a range of functional structures, the size of the patch can be precisely regulated in our models. In the first stageself-assembly，we only allow A-A hydrophobic attraction at low concentrationto refine self-assembly subunits for next stage.In the second stage, B-B hydrophobic attraction is also allowed to generatethe the second stage self-assembly structures. By regulation the interactionbetween patch B as well as the concentration of patchy particles, the factors thatinfluence the ordered structures are studied. Via properly designing theassembly models, routes and rules, we can observe the formation of honeycombnetwork structure and diamond structures, respectively. The results reveal thatthe strong attraction between patch B is good for honeycomb network structureformation in solution with suitable patchy particle concentrations. But it isnecessary to choose appropriate attraction between patch B and theconcentration to get the diamond structures.