Dendrimers and Hyperbranched Polymers: Two Families of Three-Dimensional Macromolecules with Similar but Clearly Distinct Properties

Abstract Dendrimers and hyperbranched polymers are globular macromolecules that are characterized both by a highly branched structure, in which all bonds converge to a focal point or core, and a multiplicity of reactive chain-ends. Because of the obvious similarity of their building blocks, many assume that the properties of these two families of dendritic macromolecules are almost identical and that the terms “dendrimer” and “hyperbranched polymer” can be used interchangeably. This assumption is incorrect because only regular dendrimers have a precise end-group multiplicity and functionality and exhibit properties that are totally unlike those of all other families of macromolecules. For example, regular dendrimers display a maximum in the relationship between their intrinsic the applications that are contemplated for the dendritic polymers. Using living systems as a model, one must anticipate that the regular placement of reactive groups at a precise location, as opposed to throughout a structure, has great importance in terms of ultimate performance when surface and interfacial properties are involved. Therefore, just like Langmuir-Blodgett films, dendrimers belong to a special class of well-defined molecular architectures where exact structure and ultimate performance are intimately related. It is likely that regular dendrimers will continue to draw much attention in specialized applications that take advantage of their precise architecture: drug delivery, catalysis, nanoreactors, molecular devices, etc. In contrast, hyperbranched polymers will join other interesting functional polymers in applications that involve commodity materials: from coatings and adhesives to lubricants, compatibilizers, and carriers. Today, the frontiers in the chemistry of dendritic polymer are in the search for rapid methods of synthesis involving, for example, vinyl polymerizations [46, 50], the preparation of “engineered” dendritic structures, and the discovery of new properties and applications [1, 47].