Nanoscopic supermolecules with linear‐dendritic architecture: Their preparation and their supramolecular behavior

The design, synthesis, and properties of supermolecules consisting of well defined assemblies of linear and globular macromolecules is studied. Therefore, several families of hybrid block polymers based on polyether dendrimers linked to well‐defined blocks of polyethylene oxide, polyethylene glycol, polyester, or polystyrene have been prepared. The unique topological macromolecules that result from the assembly of such components having different shapes and internal densities can assemble in highly stable supramolecular micelles whose characteristics vary as a function of the medium. The hybrid macromolecules are usually prepared by the nucleophilic displacement of a reactive functionality located at the focal point of a convergent polyether dendrimer, with a nucleophilic anion located at one or both chain ends of a linear polymer. Alternately, the focal point of the dendrimer may be used to attach a polymerizable vinyl group affording a dendritic macromonomer that may be used to create variety of copolymers. Finally, the focal point of the convergent dendrimer may serve as an initiator in the polymerization of a linear chain thereby affording the hybrid linear‐dendritic entity. In the latter case the unique microenvironment provided by the dendrimer is useful in the prevention of undesirable side‐reactions during growth of the linear block. This demonstrates that the differences between the globular and linear fragments of these unique molecules can be used to design nanoscale reactors that perform functions not normally achieved with small molecules. The very unusual solution properties of the dendritic‐linear supermolecules are a direct result of the forced combination of their dissimilar building blocks.