Hyperbranched polymers: a promising new class of materials

Hyperbranched polymers are highly branched macromolecules that are prepared through a one-step polymerization process. Many kinds of hyperbranched polymers have been investigated as novel dendritic, macromolecules. The general concepts, syntheses and the properties of hyperbranched polymers are reviewed in this article. The polymerization reactions are classified into three categories: (1) step-growth polycondensation of AB, monomers; and (2) self-condensing vinyl polymerization of AB* monomers; (3) multibranching ring-opening polymerization of latent AB, monomers. Hyperbranched polymers are generally composed of dendritic, linear and terminal units and a degree of branching (DB) helps to describe their structures. It has been shown that most of the hyperbranched polymers possess some of the unique properties exhibit dendritic macromolecules, such as low viscosity, good solubility, and multi-functionality. Owing to multi-functionality, physical properties such as solubility in solvents and the glass transition temperature can be controlled by the chemical modification of the end functional groups (endcapping reactions). Applications of designed hyperbranched polymers to specific fields are also described. (C) 2001 Elsevier Science Ltd. All rights reserved.