1. Nearly complete nanoscale size and mass monodispersity
2. The ability to control congestion, shape, and nanocontainer/scaffolding properties as function of generation
3. Mathematically defined exponential amplification and functionalization of
dendrimer surface chemistry
4. Nanoscale dimensions and shape mimicry of proteins
5. Dendrimer interior guest–host encapsulation properties for both inorganic and
organic guests
These features are captured to some degree with dendrigraft polymers; however,
they are either absent or present to a vanishing small extent for random
hyperbranched polymers.
5 Unique Quantized Dendrimer Properties
5.1 Critical Nanoscale Design Parameters
The structure-controlled features manifested by dendrons/dendrimers, such as: size,
shape, surface chemistry, flexibility/rigidity, elemental composition, and architecture,
have provided a unique window to a new systematic concept for unifying
nanoscience and will be described later in Section 6. These nanolevel structurecontrolled features are referred to as “critical nanoscale design parameters” (CNDPs).
5.1.1 Controlled Nanoscale Monodispersity
The monodispersed nature of dendrimers has been verified extensively by mass
spectroscopy, size exclusion chromatography, gel electrophoresis, and transmission
electron microscopy (TEM) [55, 115]. As is always the case, the level of
monodispersity is determined by the skill of the synthetic chemist, as well as the
isolation or purification methods utilized. In general, convergent methods produce the
most nearly isomolecular dendrimers. This is because the convergent growth process
allows purification at each step of the synthesis and eliminates cumulative effects due
to failed couplings [85, 116]. Appropriately purified, convergent dendrimers are
probably the most precise synthetic macromolecules that exist today.
As discussed earlier, mass spectroscopy has shown that PAMAM dendrimers
produced by the divergent method are very monodisperse and have masses consistent with predicted values for the earlier generations (i.e., G ¼ 0–5) (Fig. 13). Even
at higher generations, as one enters the de Gennes dense packed region, the
molecular weight distributions remain very narrow (i.e., 1.05) and consistent, in
spite of the fact that experimental masses deviate substantially from predicted
theoretical values. Presumably, de Gennes dense packing produces a very regular
and dependable effect that is manifested by the observed narrow molecular weight
distribution.
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D.A. Tomalia
2. The ability to control congestion, shape, and nanocontainer/scaffolding properties as function of generation
3. Mathematically defined exponential amplification and functionalization of
dendrimer surface chemistry
4. Nanoscale dimensions and shape mimicry of proteins
5. Dendrimer interior guest–host encapsulation properties for both inorganic and
organic guests
These features are captured to some degree with dendrigraft polymers; however,
they are either absent or present to a vanishing small extent for random
hyperbranched polymers.
5 Unique Quantized Dendrimer Properties
5.1 Critical Nanoscale Design Parameters
The structure-controlled features manifested by dendrons/dendrimers, such as: size,
shape, surface chemistry, flexibility/rigidity, elemental composition, and architecture,
have provided a unique window to a new systematic concept for unifying
nanoscience and will be described later in Section 6. These nanolevel structurecontrolled features are referred to as “critical nanoscale design parameters” (CNDPs).
5.1.1 Controlled Nanoscale Monodispersity
The monodispersed nature of dendrimers has been verified extensively by mass
spectroscopy, size exclusion chromatography, gel electrophoresis, and transmission
electron microscopy (TEM) [55, 115]. As is always the case, the level of
monodispersity is determined by the skill of the synthetic chemist, as well as the
isolation or purification methods utilized. In general, convergent methods produce the
most nearly isomolecular dendrimers. This is because the convergent growth process
allows purification at each step of the synthesis and eliminates cumulative effects due
to failed couplings [85, 116]. Appropriately purified, convergent dendrimers are
probably the most precise synthetic macromolecules that exist today.
As discussed earlier, mass spectroscopy has shown that PAMAM dendrimers
produced by the divergent method are very monodisperse and have masses consistent with predicted values for the earlier generations (i.e., G ¼ 0–5) (Fig. 13). Even
at higher generations, as one enters the de Gennes dense packed region, the
molecular weight distributions remain very narrow (i.e., 1.05) and consistent, in
spite of the fact that experimental masses deviate substantially from predicted
theoretical values. Presumably, de Gennes dense packing produces a very regular
and dependable effect that is manifested by the observed narrow molecular weight
distribution.
348
D.A. Tomalia