Manipulation of Cracks in Three-Dimensional Colloidal Crystal Films via Recognition of Surface Energy Patterns: An Approach to Regulating Crack Patterns and Shaping Microcrystals

A new concept for dealing with cracks in colloidal crystals has been proposed. We induce the cracks rather than eliminate them via templates that possess hydrophilic/hydrophobic patterns on the surface (surface energy patterns), leading the cracks to propagate along the predetermined lines. Colloidal crystal arrays with various kinds of element figures separated by cracks could be reproducibly fabricated. Diverse crack patterns other than common stripes have been observed, and the mechanism of these behaviors has been explored. The factors that influence the crack density have been investigated to ensure that the templates could function effectively. Moreover, we obtained microcrystal blocks with specific shapes, detached from the substrate.