  We study the influence of mutual interaction on the conformation of flexible
poly(propyleneamine) dendrimers of fourth generation in concentrated solution.
Mixtures of dendrimers with protonated and deuterated end groups are
investigated by small-angle neutron scattering up to volume fractions of 0.23.
This value is in the range of the overlap concentration of the dendrimers. The
contrast between the solute and the solvent was varied by using mixtures of
protonated and deuterated solvents. This allows us to investigate the partial
structure factors of the deuterated dendrimers in detail. An analysis of the
measured scattering intensities reveals that the shape of the flexible
dendrimers is practically independent of the concentration in contrast to the
pronounced conformational changes of flexible linear polymers.
