Highly ordered mesoporous SBA-15 silica with large pore diameter of 18 nm (nominal BJH pore diameter similar to 22 nm) and short pore length (similar to 500 nm) was synthesized using a micelle expander 1,3,5-triisopropyl-benzene in the absence of ammonium fluoride by employing short initial stirring time at 17 degrees C followed by static aging at low temperature. Scanning and transmission electron microscopies revealed that the material comprised of platelet particles in which large mesopores were nearly flawlessly arranged within uniform domains up to 3 mu m in size. The platelet SBA-15 had the (100) interplanar spacing of 17 nm, high surface area (similar to 470 m(2) g(-1)) and large pore volume (similar to 1.6 cm(3) g(-1)). The hydrothermal treatment at 130 degrees C for 2 days was employed to eliminate constrictions from the pore channels. The control experiment showed that a sample prepared with prolonged stirring had very similar mesoporous properties, but the particle size was smaller and the domains were irregular, proving that the static conditions facilitate the formation of SBA-15 with platelet particle morphology. The absence of ammonium fluoride was also critical in attaining the platelet particle shape. (C) 2011 Elsevier Inc. All rights reserved.