Photocontrolled self-assembly of silica nanoparticles at two scales.

The photocontrolled self-assembly of coumarin-functionalized silica nanoparticles is fabricated and investigated. When these nanoparticles are uniformly dispersed in CHCl3 solution under 365 nm light illumination, four novel kinds of patterns are self-assembled on the bottom of glass beakers: circle patterns, square plate patterns, semi-annular and annular patterns, swirling patterns, which can be seen with the naked eye. Furthermore, these four patterns exhibit similar nanoscale morphologies: ring-like necklaces in nanoscale dimensions, and reveal interesting superhydrophobic property. In short, there exist two kinds of self-assembly of functionalized silica nanoparticles in two radically different dimensions, which can be potentially applied in self-cleaning fields and the construction of photocontrolled nanoscale structures and macroscale structures.