Depletion-interaction-driven assembly of golf ball-like particles for development of colloidal macromolecules.

Colloidal molecules created by clustering monodisperse particles are a significant model system of atoms and molecules in colloidal scale. To attain modelling of complex or high-molecular-weight molecules such as hyper-branched polymers and proteins, it is required to develop a new assembling system which can prepare three-dimensionally designed colloidal molecules. In this study, we proposed an approach for complex colloidal molecules created by association between golf ball-like particles and spherical particles via depletion interaction. Several golf ball-like particles joined together, which formed joined particle assemblies at the spherical particles acting as their joints in a depletant solution. The number of golf ball-like particles in a particle assembly was increased by increasing the concentration of the depletant, leading to the formation of branched colloidal chains of the golf ball-like particles. Because the golf ball-like particles in the colloidal chain flexibly rotated at their joints, the conformation of the chains varied in the depletant solution. The present results demonstrated that the golf-ball like particle that can be joined to form colloidal macromolecules with high association number and high flexibility will be a promising building block for complex colloidal model systems.