Dendrimers

Dendrimers represent a class of regular branched polymers with a treelike, dendritic structure.Starburst dendrimers are synthesized from a multi- functional core with each addition of the Repeat unit undergoing controlled branching with constant multiplication of the number of monomers from a generation to the next [1]. In the case of the star-like dendrimers there are several monomer units between the branching points resulting in a more loose star-like structure [2]. Because of their application potential, for example, as carriers for biological and chemical materials, controlled release agents, catalyst scaffolds or polymer modifiers, dendrimers have caught the interest of a wide range of scientists. Their potential is highly dependent (1) in their uniform size and shape characteristics, (2) on the large number of modifiable reactive end groups and (3) on their internal structure (radial segment density profile). We addressed the shape and internal structure with small angle X-ray (synchrotron) and neutron scattering in solution at low concentrations [2, 3]. The experimental results are compared with computer simulation experiments. The method is described more detailed in [3, 4]. Furthermore we studied the intra-dendrimers dynamics by means of neutron spin-echo spectroscopy. Considering the hybrid character of dendrimers between polymer-like entities and colloidal particles we also wish to investigate ordering phenomena and collective dynamics in the high concentration range. [1] M. Trollsas and J.L. Hedrick, J. Am. Chem. Soc. 120 (1998) 4644. [2] S. Rathgeber et al., ACS preprint, PMSE, 84 (2001). [3] S. Rathgeber et al., submitted to J. Appl. Phys. A. [4] A. Tomalia et al., Encyclopedia of Polymer Science and Engineering, Wiley, New York, 1990. [5] T. Pakula, Comp. Theor. Polym. Sci. 8 (1998) 21. [6] T. Pakula et al., Macromolecules 25 (1998) 8931.