Directed growth of colloidal crystals on a hydrophobic polymer film by using hydrophilic traps

Deposition of colloidal crystal films onto a hydrophobic surface using capillary force-induced self-assembly is difficult to achieve because of wetting problems of the aqueous colloids with the substrate. We present here a method to overcome this problem. By introducing a hydrophilic trench around the hydrophobic polymer, uniform crystalline colloidal films can be deposited onto the surface of the polymer, provided a sufficient volume of suspension is used. The hydrophilic area around the polymer acts like an artificial trap that can help pin the colloidal suspension on the surface of the hydrophobic polymer surface and direct the self-assembly of colloidal spheres, which is the key to fabricate a uniform colloidal crystal film on the polymer surface.