| Abstract
| - Conformational properties of neutral and charged dendrimers in dilute solutions of differentquality have been investigated by a mean-field analytical approach and by Brownian dynamics (BD)computer simulation for systems up to generation six. Radial monomer distribution and mass distributionfunctions, radii of gyration, and structure factors have been studied as functions of solvent quality, effectivecharge of the terminal groups, and Debye screening radius. For high-generation dendrimers BDsimulations show that the dendrimers hardly fluctuate. Swelling of both neutral and charged dendrimersis reasonably described by a generalized Flory mean-field theory in which the two-body virial term isreplaced by the sum of the excluded-volume and two-body attraction terms. A non-Gaussian term takinginto account the finite extensibility of spacers and a Coulomb term in the form of the Debye−Hückelapproximation have been included as well. The θ-point for a single dendrimer molecule is defined as thecharacteristic energy of the excluded-volume interactions when the linear expansion factor α is equal tounity. In contrast to linear polymers, the θ-point defined in such way is different from that calculated asthe characteristic energy when scaling relation for a good-solvent conditions stops to be valid. Dendriticterminal groups are distributed through the whole volume of the molecule, but the maximum of thisdistribution is shifted toward the periphery with increase of Debye screening radius and effective chargeof a terminal group. It is shown that fractal dimension of a neutral dendrimer depends on both itsgeneration number and spacer length.
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