Advances in hyperbranched polymer chemistry

Hyperbranched polymers are densely packed macromolecules whose three-dimensional framework consists of a core and three or more branched short composite chains, namely dendrons. They have a spherical architecture and unique properties, such as nanoscale macromolecules (2–100 nm), high solubility, the presence of several branched chains, spatial voids and a large number of end functional groups. Various classes of hyperbranched polymers in the last 10 years such as polyalkanes, polyarylenes, polyhalides, organometallic polymers, polyethers, polyesters, nitrogen-containing and polyheterocyclic compounds are reviewed. These polymers can be readily obtained under mild conditions by polymerization, polycondensation or polycoupling reactions of polyfunctional monomers. The main characteristics confirming the hyperbranched structure of polymers are: low molecular weight, dispersity, medium degree of branching, large number of end functional groups, nanoscale macromolecules, three-dimensional architecture, presence of glass transition temperature, high solubility in various organic solvents, and low viscosity of polymer solutions. Due to their adaptable structures and special properties, hyperbranched polymers are widely used as hybrid materials and composites for structural applications, coatings, adhesives, membranes, catalysts, flame retardants, plasticizers, and light-emitting materials. The hyperbranched structure combined with low toxicity allows their use as highly effective nanoscale anticancer and bactericidal drugs, as well as contrast reagents for magnetic resonance tomography. The availability of technologically significant methods for the synthesis of hyperbranched polymers of various types makes it possible to carry out their industrial production on a scale sufficient for practical application in solving modern problems of biomedical chemistry and in many other branches of science and industry.