Polyaniline (PANI) "sunflowers" made of arrays of oriented nanorods were synthesized by chemical oxidative polymerization of aniline in the presence of cetyltrimethylammonium bromide (CTAB) and suitable concentration of HNO3 at about 0 degrees C (ice bath). The reaction conditions, such as the concentration of reagents and reaction temperature were systematically investigated and controlled on the preparation of PANT "sunflowers". The results also suggest that HNO3 probably plays a key role in forming PANT "sunflowers". A possible forming mechanism of the PANI nanostructures is offered. (c) 2009 Published by Elsevier Inc.