Dendrimers as Building Blocks for Nanostructured Materials:  Micro- and Mesoporosity in Dendrimer-Based Xerogels

Recently the authors have been exploring the use of dendrimeric building blocks in the construction of new types of nanostructured materials. In principle, this may be accomplished with use of various chemical interactions for linking the dendrimers together. For example, highly charged dendrimers of opposite charge might assemble via electrostatic forces into superlattice structures. Another approach involves the covalent assembly of dendrimer building blocks into network structures using coupling reactions between functional end groups on the dendrimer surface. Spherically shaped dendrimers may be expected to pack into networks possessing interstitial spaces whose size is influenced by the radius of the dendrimer building block. With this approach, it should be possible to generate new classes of porous materials with tunable pore sizes and inclusion properties. For such materials, one might expect that pore diameters would increase, and surface areas decrease, with higher dendrimer generations. In summary, this work has produced dendrimer-based xerogels that exhibit high surface areas, and an interesting observation with respect to the relationship between generation number and surface area has been made. Future work will address the influence of various synthetic conditions on the structures of the gels. Also, the authors intend to investigate the properties of these new materials as molecular sieves, porous membranes, and catalyst supports.