Facile sol-gel synthesis of porous silicas using poly(propylene)imine dendrimers as templates

Commercially available poly(propylene)imine (DAB-Am-32 and DAB-Am-64) dendr imers were used as single-molecule templates to tailor the porosity of sili cas via a nonacidic sol-gel method. X-ray diffraction on both the as-prepar ed (oven-dried at 373 K) and the calcined (833 K) materials revealed that m odest contraction took place on template removal and that the cavities crea ted did not achieve three-dimensional ordering under the current synthesis conditions. Transmission electron microscopy of "Pt-stained" samples suppor ted this picture. A modified Horvath-Kawazoe analysis of the argon adsorpti on isotherms indicated that DAB-Am-64 is a much more effective template tha n DAB-Am-32, Pyrolysis and oxidation protocols for template removal are als o presented.