Dendritic polysiloxane

The vinyl groups on dendritic polysiloxanes were transformed to functional groups. Thus,... 

Keywords silica hybrid, modified silica, dendritic polysiloxane, functionalized polysiloxane, supported catalyst, platinum, hydrosilylation... 

Although some interest has been shown in the construction of dendritic polysiloxane... 

While polymers most commonly consist of carbon, nitrogen and oxygen, hybrid materials containing metals or other elements represent an important class of materials [76-78]. Hybrid materials too have been used as hyperbranched grafts. Two examples of such materials are described here. The first is a polysiloxane graft. The second is a dendritic coordination polymer based on a thermally and oxygen stable Pd(II) pincer complex [79]. 

Repetitive silicon-based transformations were then employed for dendritic construction. Palladium-catalyzed silane hydroxylation of the core 71 afforded triol 73, which was then treated with three equivalents of monochloropolysiloxane 72 to generate the hexa-hydrido, first generation dendrimer 74. Further application of the Pd-mediated hydroxylation, followed by attachment of monochloro-monomer 72, led to the second (75) and third (76) generation polysiloxane cascades. 

Keywords polysiloxanes, cyclotrisiloxanes, anionic polymerization siloxane copolymers, block copolymers, dendritic polymers... 

Synthesis of Star-Branched and Dendritic-Branched Functionalized Polysiloxanes... 

Scheme 6. Synthesis of dendritic-branched, fimctional polysiloxane.

Anionic polymerization of functionalized cyclotrisiloxanes is a good method for the synthesis of well-defined functionalized polysiloxane with control of molecular mass, polydispersion, and density and arrangement of functional groups. These polymers may serve as reactive blocks for the building of macromolecular architectures, such as all-siloxane and organic-siloxane block and graft copolymers, star-, comb- and dendritic-branched copolymers and various polysiloxane-inorganic solid hybrids. 

Zamora, M. Bruna, S. Alonso, B. Cuadrado, 1., Polysiloxanes Bearing Pendant Redox-Active Dendritic Wedges Containing Ferrocenjd and (T 6-Aryl)tricar-bonylchromium Moieties. Macromolectdes 2011,44 (20), 7994-8007. 

Chojnowski, J. Fortuniak, W. Scibiorek, M. Rozga-Wijas, K. Grzelka, A. Mizerska, U., 3-Chloropropyl Functionalized Dendrigraft Polysiloxanes and Dendritic Polyelectrolytes. Macromolecules 2007, 40, 9339-9347. 

Vast arrays of metal-containing polymers have been produced that offer a wide variety of properties. Key milestones in the history of this diverse topic and a sense of its growth and importance were discussed in this chapter. While initial efforts focused on polysiloxanes, today s efforts are quite diverse and include the production of multisite catalysts, variable oxidation state materials, and smart materials where the precise structure can be changed through the introduction of different counterions. These polymers have been produced by all of the well-established polymerization methodologies. The metal atoms reside as part of the macromolecular backbone, in sidechains, coordinated to the backbone, and as integral parts of dendrites, stars, and rods. Truly, many of tomorrow s critically important materials will have metal atoms as an integral part of the polymer framework, which will allow the materials to function as demanded. 

Zamora M, Bruna S, Alonso B, Cuadrado I (2011) Polysiloxanes bearing pendant redox-active dendritic wedges containing ferrocenyl and (q6-aryl)tricarb[Pg.188]

---