Hyperbranched polymers

Polymers obtained from the statistical polymerization of A(x)B monomers by means of condensation or addition procedures are referred to as hyperbranch ed polymers. The paper aims to give a brief historical background and to gi ve a survey of hyperbranched polymers in the literature. Polymerization of A(x)B monomers yields highly branched polymers, with a mu ltitude of end groups, which are less prone than linear polymers to form en tanglements and undergo crystallization. Hyperbranched polymers are phenome nologically different from linear polymers; for example, the lack of entang lements results in lower viscosity than in linear polymers of the same mole cular weight. The thermal properties of hyperbranched polymers have been sh own 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 tailo red by changing the nature of the end groups. For some areas, such as coati ng resins and tougheners in epoxy-resins, hyperbranched polymers are forese en to play an important role. Various applications have been suggested, eve n though only a few have been commercialized at this time.