During drying, an aqueous suspension of strongly charged halloysite clay nanotubes concentrates at the edge of the droplet ("coffee-ring" effect) which provides alignment of the tubes along the liquid-substrate contact line. First, the surface charge of the nanotubes was enhanced by polyanion adsorption inside of the lumen to compensate for the internal' positive charges. This increased the magnitude of the xi-potential of the tubes from 36 to 81 mV and stabilized the colloids. Then, colloidal halloysite was dropped onto the substrate, dried at 65 degrees C and after a concentration of similar to 0.05 mg mL(-1) was reached, the alignment of nanotubes occurred starting from the droplet edges. The process was described with Onsager's theory, in which longer nanorods, which have higher surface charge, give better ordering after a critical concentration is reached. This study indicates a new application of halloysite clay nanotubes in polymeric composites with anisotropic properties, microchannel orientation, and production of coatings with aligned nanotubes. (C) 2014 Elsevier Inc. All rights reserved.