| Abstract
| - The structural properties of charged G5 poly(propyleneimine) dendrimers (Astramol) inD2O solutions have been investigated using small-angle neutron scattering. Upon addition of acid (HCl),the dendrimers become charged, and the scattered patterns exhibit a single correlation peak indicatinga spatial arrangement of the molecules in the acidified medium due to the electrostatic repulsion. Itsposition Q* is shifted toward wider angles by increasing the dendrimers concentration, leading to a scalingrelation Q* ∼ φ0.32±0.01. This relationship indicates that the system has a liquidlike structural arrangement.The electrostatic interactions can be screened by addition of salt (NaCl). The short-range interactionsbetween the dendrimer molecules were investigated by systematically varying the salt concentration inthe solution. We demonstrate that the peak intensity decreases monotonically by increasing the saltconcentration. In addition, this system shows a steep upturn in the scattered intensities at low wavevectorreflecting the presence of large-scale structures, likely indicating aggregation of dendrimers or otherinhomogeneous molecular distribution.
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