consider the “patched” PPDs as synthetic substitutes of transport proteins, which
are also characterized by polar and unipolar surfaces areas of varying size [58].
Dendrimers are without doubt a unique case of 3D macromolecules. In this class,
PPDs stand out because of the rigidity of the dendrons, which excludes backbending. This leads to a pronounced rigidity of the shape, which can be further
controlled by choice of the core and the branching points.
2.7 Conclusions
This brief overview illustrates that PPDs (1) are a challenging case of precision
macromolecular synthesis; (2) define ample questions for supramolecular studies
such as guest uptake, aggregation in solution, and controlled deposition on surfaces;
(3) stimulate many functional investigations into sensing and optoelectronics,
cell biology, and nanomedicine; and (4), as justified above, are suited for the
fabrication of real devices such as ultrastable LEDs. In the meantime, a firm
dendrimer community has been established for which the function of the these
macromolecules stands in the foreground. It is, indeed, worthwhile to push the limits
of complex dendrimer functions even if polymer nanoparticles or hyperbranched
polymers are sometimes claimed to do the same job, but at lower cost. In any case,
PPDs are unique among the dendrimers due to their structural perfection, stability,
and shape-persistence.
3 Cylindrical Brush Polymers
3.1 Introduction
Like the PPDs, cylindrical brush polymers owe their properties to a very special
macromolecular design. Attaching many side chains to a polymer backbone is
another way of creating a spatially defined rigidity. The length and grafting density
of the side chains on a polymer backbone has a profound and tunable influence on
the structure and dynamics of the macromolecules. A further option is to introduce
ionic charges on the side chains, leading to novel polyelectrolyte structures. PPDs
and cylindrical brush polymers, special examples of unconventional polymer
topologies, thus jointly offer two challenging possibilities: studying intra- and
intermolecular structural changes in cases of controllable rigidity and gaining
insight into unprecedented polyelectrolytes.
Bottlebrush polymers contain a long flexible macromolecule as a backbone to
which side chains, which may also be flexible, are grafted [59, 60]. The idea then is
that via suitable choices of parameters such as the grafting density, solvent quality,
and side chain molecular weight the local stiffness of this cylindrical molecular
brush can be controlled. The qualitative picture one draws is that of a wormlike
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K. Binder et al.
are also characterized by polar and unipolar surfaces areas of varying size [58].
Dendrimers are without doubt a unique case of 3D macromolecules. In this class,
PPDs stand out because of the rigidity of the dendrons, which excludes backbending. This leads to a pronounced rigidity of the shape, which can be further
controlled by choice of the core and the branching points.
2.7 Conclusions
This brief overview illustrates that PPDs (1) are a challenging case of precision
macromolecular synthesis; (2) define ample questions for supramolecular studies
such as guest uptake, aggregation in solution, and controlled deposition on surfaces;
(3) stimulate many functional investigations into sensing and optoelectronics,
cell biology, and nanomedicine; and (4), as justified above, are suited for the
fabrication of real devices such as ultrastable LEDs. In the meantime, a firm
dendrimer community has been established for which the function of the these
macromolecules stands in the foreground. It is, indeed, worthwhile to push the limits
of complex dendrimer functions even if polymer nanoparticles or hyperbranched
polymers are sometimes claimed to do the same job, but at lower cost. In any case,
PPDs are unique among the dendrimers due to their structural perfection, stability,
and shape-persistence.
3 Cylindrical Brush Polymers
3.1 Introduction
Like the PPDs, cylindrical brush polymers owe their properties to a very special
macromolecular design. Attaching many side chains to a polymer backbone is
another way of creating a spatially defined rigidity. The length and grafting density
of the side chains on a polymer backbone has a profound and tunable influence on
the structure and dynamics of the macromolecules. A further option is to introduce
ionic charges on the side chains, leading to novel polyelectrolyte structures. PPDs
and cylindrical brush polymers, special examples of unconventional polymer
topologies, thus jointly offer two challenging possibilities: studying intra- and
intermolecular structural changes in cases of controllable rigidity and gaining
insight into unprecedented polyelectrolytes.
Bottlebrush polymers contain a long flexible macromolecule as a backbone to
which side chains, which may also be flexible, are grafted [59, 60]. The idea then is
that via suitable choices of parameters such as the grafting density, solvent quality,
and side chain molecular weight the local stiffness of this cylindrical molecular
brush can be controlled. The qualitative picture one draws is that of a wormlike
132
K. Binder et al.