8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Fri 911:10-14:00P4.19Conformations and interactions of charged dendrimersin implicit and explicit solventsSebastian Huissmann, 1 Ronald Blaak, 1 and Christos N. Likos 11 Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090, Wien, AustriaDendrimers are highly ordered polymeric macromolecules whose overall charge can be regulatedby the pH of the solvent. Advanced synthesis techniques provide control over their microscopicproperties, such as the location of the chargeable groups within the molecule. We investigate theconformations and interactions of dendrimers with different spacer lengths between the subsequentgenerations under a changing environment. To this end, monomer-resolved molecular dynamics(MD) simulations in combination with the Ewald summation technique have been employed. Achange of the pH value of the solution is modeled by charging the dendrimers in different ways. Aconsiderable stretching of the dendrimers can be observed for large generation number and spacerlength. Upon charging dendrimers with high generation and long spacer chains, an opening-up oflarge voids within the dendrimer is found. The effect of explicitly modeled solvent molecules onthe conformation of dendrimers under varying pH conditions is studied by employing the SPC/Emodel for water. A large discrepancy can be observed for neutral dendrimers, which are moredensely packed in an explicit solvent. However, fully charged dendrimers show very good agreementand the water-intake therefore increases with the charge of the dendrimer. Furthermore weinvestigate the influence of the dendrimer charge as well as the salinity on the interaction betweendendrimers of varying spacer length. A stronger repulsion is obtained the higher the charge of thedendrimers, while the interaction becomes softer for larger spacer lengths. By adding divalent saltmolecules to the solution, the effective force can be reduced down to values of neutral dendrimers.19