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type nano-compounds [7], whereas, dendrimers bearing either surface or interior
ligation sites reacted with metal salts to produce stoichiometric dendrimer-metal
ligation type nano-compounds [8,9]. Some of these constructs could be further
reduced to yield core-shell; dendrimer-metal nano-cluster type nano-compounds.
These results optimistically portend the extension of this concept to awide variety of
other well-defined soft particle nano-element categories (i.e., proteins, DNA/RNA,
viral capsids, etc.), and hard particle nano-element categories (i.e., metal oxide
nanocrystals, metal chalcogenide nanocrystals, fullerenes, etc.).
1.2 CRITICAL NANOSCALE DESIGN PARAMETERS (CNDPs):
STRUCTURAL CONTROL IN DENDRIMERS
Dendrimers are widely recognized as an important subclass within the fourth
major polymer architecture category referred to as (IV) dendritic polymers [10]
(see Figure 1.3). Hierarchically speaking, dendrimers are collections of 10
3
-10
4
atoms with relative molar masses of 10
4
-10
5
Da and hydrodynamic dimensions
ranging from 1 to 30 nm. Among the most important features of dendrimers is that
they can be synthesized with precise structural control over their CNDP's, which
include nanoscale: (a) sizes,(b)shapes,(c)surface chemistries,(d)flexibilities/
rigidities,and(e)architecture [11]. This is in sharp contrast to statistical poly-
dispersed features which are normally associated with traditional polymer archi-
tectures, namely: (I) linear, (II) cross-linked polymers, and (III) branched types as
shown in Figure 1.3.
FIGURE 1.3
Four major classes of macromolecular architecture. Traditional synthetic
polymers: (I) linear, (II) cross-linked (bridged), and (III) branched. Structure controlled
polymers (IV) dendritic.
