Hyperbranched polymers

Polymers obtained from the statistical polymerization of A(x)B monomers by means of condensation or addition procedures are referred to as hyperbranched polymers. The paper aims to give a brief historical background and to give a survey of hyperbranched polymers in the literature. Polymerization of A(x)B monomers yields highly branched polymers, with a multitude of end groups, which are less prone than linear polymers to form entanglements and undergo crystallization. Hyperbranched polymers are phenomenologically different from linear polymers; for example, the lack of entanglements results in lower viscosity than in linear polymers of the same molecular weight. The thermal properties of hyperbranched polymers have been shown to depend on the nature of the chain ends. The lower the polarity, the lower the glass transition temperature since it is suggested that the glass transition of hyperbranched polymers is due to translational motions. Hyperbranched polymers are unique in that their properties ape easily tailored by changing the nature of the end groups. For some areas, such as coating resins and tougheners in epoxy-resins, hyperbranched polymers are foreseen to play an important role. Various applications have been suggested, even though only a few have been commercialized at this time.