Hyperbranched macromolecules

In 1941, Flory80 introduced the concept of hyperbranched macromolecules by polymerization of a trifunctional AB2 monomer (Fig. 5.16). From a chemical point of view, perfectly defined structures were obtained when the monomer reactions were performed step by step At each step, a polyfunctional molecule... 

However, dendrimeric and hyperbranched polyesters are more soluble than the linear ones (respectively 1.05, 0.70, and 0.02 g/mL in acetone). The solution behavior has been investigated, and in the case of aromatic hyperbranched polyesters,84 a very low a-value of the Mark-Houvink-Sakurada equation 0/ = KMa) and low intrinsic viscosity were observed. Frechet presented a description of the intrinsic viscosity as a function of the molar mass85 for different architectures The hyperbranched macromolecules show a nonlinear variation for low molecular weight and a bell-shaped curve is observed in the case of dendrimers (Fig. 5.18). 

Hyperbranched polymers generally have very low melt and indinsic viscosities. The large number of chain-end functional groups present in hyperbranched macromolecules have also been shown to dramatically affect physical properties... 

Sheiko SS, Moller M (2001) Hyperbranched Macromolecules Soft Particles with Adjustable Shape and Capability to Persistent Motion. 212 137-175 Shen B (2000) The Biosynthesis of Aromatic Polyketides. 209 1-51 Shinkai S, see James TD (2002) 218 159-200 Shirakawa E, see Hiyama T (2002) 219 61-85 Shogren-Knaak M, see Imperial B (1999) 202 1-38 Sinou D (1999) Metal Catalysis in Water. 206 41-59... 

In a concurrently published report [160] Crooks and coworkers reported similar MUA-SAMs modified by covalent linking of hyperbranched macromolecules. These films containing a high density of surface carboxylic acid groups could selectively bind metal ions or undergo chemical modification. 

Hawker, C.). Dentritic and Hyperbranched Macromolecules Precisely Controlled Macro-molecular Architectures. Vol. 147, pp. 113-160. 

Ferrocene-based Branched Polymers (Dendrimers). One of the topics in macromolecular chemistry is constituted by dendrimers, or hyperbranched macromolecules of tridimensional globular structure, the surface of which is characterized by a large number of functional groups, Scheme 4. Such functionalities impart to the molecules solubility, viscosity and thermal properties different from those of the common linear polymers.38c,d 44... 

Hyperbranched Macromolecules Soft Particles with Adjustable Shape and Persistent Motion Capability... 

Keywords. Hyperbranched macromolecules. Polymer films. Scanning force microscopy. Conformational transitions and interfacial ordering of single molecules... 

Fig. 2a-c. Monolayer structure of a small molecules b solid particles c hyperbranched macromolecules... 

Dendritic and Hyperbranched Macromolecules -Precisely Controlled Macromolecular Architectures... 

---