Dendrigraft Arborescent Polymers

In spite of this difficult acceptance, it is quite remarkable to note that by the end of 1990 about two dozen publications on dendrimers had appeared in refereed journals. By the end of 1991 the rate of publication of dendrimer papers had started to climb markedly while there still were only three papers on random hyperbranched polymers and two on dendrigraft or arborescent polymers. The courage, persistence and credibility of many key scientists listed in Table 1 during that period, set the stage for the explosive acceptance and recognition of dendritic polymers over the next decade. 

Scheme 6.1 General scheme for the synthesis of arborescent polymers. (Reprinted from Progress in Polymer Science, 29, S. J. Teertstra and M. Gauthier, Dendrigraft polymers Macromolecular engineering on a mesoscopic scale, 277-327, 2004, with permission from Elsevier.)...

The solution properties of dendrigraft polybutadienes are, as in the previous cases discussed, consistent with a hard sphere morphology. The intrinsic viscosity of arborescent-poly(butadienes) levels off for the G1 and G2 polymers. Additionally, the ratio of the radius of gyration in solution (Rg) to the hydrodynamic radius (Rb) of the molecules decreases from RJRb = 1.4 to 0.8 from G1 to G2. For linear polymer chains with a coiled conformation in solution, a ratio RJRb = 1.48-1.50 is expected. For rigid spheres, in comparison, a limiting value RJRb = 0.775 is predicted. 

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