Synthesis Of PAMAM Dendrimers And Its Template Action In Mesoporous Alumina

In this dissertation PAMAM dendrimers of different generations were first synthesised through divergent approach using ehtylenediane and methJ acrylate. Mesoporous granular alumina 1mm in diameterwith good micro-hardness and hight specific surface area was prepared by acid-catalysed Sol-Gel reaction of aluminum iso-propoxide . At last PAMAM dendrimers of half generations were used as organic template to tune the pore structure. Mesoporous Y -alumina of the MSU-n structure type with surface area(~300m2/g) and pore size(~4nm) have be synthesized.TG, IR, 1H-NMR, 13C-NMR were used to characterize the PAMAM dendrimers. The results indicate that PAMAM dendrimer is a class of tree-like compound constructed by repeated units starting from an initiator core. The effects of acidity and calcination tempereture on the micro-hardnees, pore volume, specific surface area and pore diameter have been reaserched. As the acidity increases, the pore volume increases and the BET surface area also presents an increasing tend, but the micro-hardness decreases and there seems to be no visible relationship between the acidity and the pore size. N2 adsorption-desorption isotherms, TEM microscopies and XRD patterns show mesoporous alumina synthesized through the traditional Sol-Gel approach had a wide pore size distribution and a poor homogeneity of the pore structure. The uncalcined samples are boehmites. After calcination no Y -alumina can be obtained. But by doping with PAMAM dendrimers, a homogeneous mesophase hybrid was obtained through self-assembly of PAMAM dendrimers and inorganic aluminum precusor. The pore size distribution of mesoporous alumina is greatly improved.