Chapter 21
Poly(amidoamine organosilicon) Dendrimers and Their Derivatives of Higher Degree of Structural Complexity
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Petar R. Dvornic and Michael J. Owen Michigan Molecular Institute, 1910 West St. Andrews Road, Midland, MI 48640
Utilization of the copolymer concept in dendrimer chemistry has provided a variety of unique radially layered copolymeric dendrimers with hydrophilic polyamidoamine (PAMAM) interiors and hydrophobic (i.e., oleophilic) organosilicon (OS) exteriors. These globular, nano-scaled inverted unimolecular micelles with different functional end-groups, generically referred to as poly(amidoamine-organosilicon) (PAMAMOS) dendrimers, have been found exceptionally versatile as precise nanoscopic building blocks for the construction of more complex forms of the structural organization of matter. Here, we describe the hierarchy of some of these forms of structural complexity and propose several possible ways by which they may contribute to materials nanotechnology.
Dendrimers are spheroidal nano-scaled macromolecules with an exceptionally high density of functionality that may reach into hundreds and thousands of functional groups per molecule (see X in Figure 1) (/). By a variety of well controlled synthetic strategies they may be prepared with a very high degree of structural regularity that is unprecedented for conventional forms of macromolecular architecture, such as linear, randomly branched or cross-linked
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© 2003 American Chemical Society
In Synthesis and Properties of Silicones and Silicone-Modified Materials; Clarson, S., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2003.
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polymers. As a consequence, they represent unique nanoscopic (i.e., 1-15 nm in diameter) reactive building blocks that open up new avenues for synthetic chemistry of more complex forms of structural organization of matter, and for creative tailor-making of previously unattainable nano-structured materials. Recently we showed that dendrimers may be prepared as compositionally copolymeric entities with significantly different repeat units (i.e., branch cells) (see Figure 1) (2). It was particularly pointed out that such a "copolymer approach" (2,5) would enable preparation of a practically unlimited variety of different dendrimers, and that by combining both architectural and compositional variations it should become possible to tailor-make a diversity of new, precisely nano-structured materials with "dialed-in" properties for specifically desired applications. In this report, we illustrate some concrete possibilities of this approach using the example of functionalized, radially layered copolymeric poly(amidoamine-organosilicon) (PAMAMOS) dendrimers as reactive building blocks for preparation of a variety of more complex forms of structural organization of matter (4).
Poly(amidoamine-organosilicon) (PAMAMOS) dendrimers Poly(amidoamine-organosilicon) (PAMAMOS) dendrimers (2,5-7) are unique radially layered inverted unimolecular micelles that consist of a hydrophilic polyamidoamine (PAMAM), -[(CH ) -C(0)-N(H)-(CH ) -N]
