Viscosity intrinsic, dendritic macromolecules

Figure 8. Intrinsic viscosity of dendritic macromolecules in THF as a function of generation number.

Figure 5.18 Variation of intrinsic viscosity as function of molar mass for linear, hyper-branched, and dendritic macromolecules.

Mourey, T.H., Turner, S.R., Rubenstein, M., Frechet, J.M.J., Hawker, C.J., and Wooley, K.L. (1992) Unique behavior of dendritic macromolecules Intrinsic viscosity of polyether dendrimers. Macromolecules 25, 2401-2406. 

While it can be expected that a number of physical properties of hyperbranched and dendritic macromolecules will be similar, it should not be assumed that all properties found for dendrimers will apply to hyperbranched macromolecules. This difference has clearly been observed in a number of different areas. As would be expected for a material intermediate between dendrimers and linear polymers, the reactivity of the chain ends is lower for hyperbranched macromolecules than for dendrimers [125]. Dendritic macromolecules would therefore possess a clear advantage in processes, which require maximum chain end reactivity such as novel catalysts. A dramatic difference is also observed when the intrinsic viscosity behavior of hyperbranched macromolecules is compared with regular dendrimers. While dendrimers are found to be the only materials that do not obey the Mark-Houwink-Sakurada relationship, hyperbranched macromolecules are found to follow this relationship, albeit with extremely low a values when compared to linear and branched polymers [126]. 

Mouiey TH, Turner SR, Rubinstein M, Fiechet JMJ, Hawker CJ, Wooley KL. Unique behavior of dendritic macromolecules intrinsic viscosity of polyether dendrimers. Macromolecules 1992 25 2401-2406. 

T.H. Mourey, S.R. Turner, M. Rubenstein, J.M.J. Frechet, C.I. Hawker, K.L. Wooley, Unique behavior of dendritic macromolecules intrinsic viscosity of polyetho" dendrimers. Macromolecules 25 (1992)2401-2406. 

A comparison of the physical properties of hyperbranched and dendritic macromolecules with linear polymers and the linear analogs of these 3-dimensional polymers is presented. It is found that thermal properties, such as glass transition temperature and degradation, are the same regardless of the macromolecular architecture but are very sensitive to the number and nature of chain end functional groups. However, other properties, such as solubility, melt viscosity, chemicd reactivity, intrinsic viscosity were found to be very dependent on the macromolecular architecture. 

Figure 2 Plot of log(intrinsic viscosity) versus log (molecular wdght) for linear (A), hyperbranched (B), and dendritic (C) macromolecules.

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