Chemistry Reference
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Figure 11.5 Two-dimensional representation of a D3G4 [D ¼ spacers (3), G ¼ dendrimer
generation (4)] dendrimer. Typical snapshots of various generations of codendrimers, from
Monte Carlo simulations, with the same number of spacers (D ¼ 2) between each branch
point. Inner H and outer H topologies are compared for three different degrees of branching
(G ¼ 1, 5, or 7). Reprinted from Connelly et al.
(2004). Copyright 2004 American
Chemical Society.
configurational-bias Monte Carlo method. They found that at later generations
when the internal monomers were in a poor solvent and the terminal monomers
were in an athermal solvent, a spherical micellar structure was adopted. Under opposite
solvation conditions (i.e., poor solvent for termini, athermal solvent for internal
monomers), a spherically symmetric loopy micelle structure emerged whereby the
end groups folded back to minimize the unfavorable interactions with solvent
(Fig. 11.6).
Lower generation dendrimers exhibited highly asymmetric conformations unless
both the internal and terminal groups interact unfavorably with the solvent, under
which conditions a compact globule conformation surrounded by a corona of
termini was formed. More recently, Suek and Lamm (2006) studied dendrimers com-
posed of a solvophobic interior surrounded by terminal monomers ranging in polarity
from all solvophobic to all solvophilic. This study also found a tendency for the
solvophilic groups to congregate at the surface. However, at high generations,
steric crowding at the periphery forced some solvophilic termini to backfold into
the dendrimer interior, consistent with the Connolly study. Increasing the solvophilic
monomer-monomer interaction by lowering the simulation temperature reduces the
tendency of the termini to backfold.
