Synthesis Of Hyperbranched Macromolecule And Their Use In Epoxy Modifying

Epoxy resins are widely used due to their excellent properties, however, the brittleness of epoxy resins limited its applications in some field. There are several ways to increase the toughness of epoxy materials, and using hyperbranched molecules to toughen epoxy resins is the latest development. Hyperbranched polymers are semi-globular in shape, are easily synthesized, have lots of terminal functional groups and internal cavities. Through modifications of terminal groups, they can afford many functions. In most literature reported, although hyperbranched macromolecules can improve the toughness of epoxies, they often have to sacrifice thermal properties. In order to toughen epoxy resin without sacrificing thermal properties, three kinds of hyperbranched polymers are synthesized, and were used to toughen epoxies.Firstly, a new AB2monomer was synthesized through a two step procedure and was then used to obtain a hyperbranched macromolecule with phenol terminal groups. The resultant hyperbranched molecues were characterized. The effects of monomer concentration, addition of core molecules, and ways of polymerization (AB2or A2+B3) on the molecular weight and polydispersity were investigated. Secondly, a series of hyperbranched macromolecules with phenolic terminal groups were synthesized using the A2+B3method by varying the A2monomers. The molecular weight distribution of hyperbranched macromolecule synthesized using the A2+B3method is wider than that using the AB2approach. Lastly, two hyperbranched epoxies were synthesized by proton transfer polymerization and by modifying terminal groups of the synthesized (phenol terminated) hyperbranched molecules. They were then used as modifiers to toughen the E-51epoxy with methylnadic anhydride as the curing agent. The hyperbranched epoxy synthesized from proton transfer polymerization can toughen the epoxy without sacrificing the thermal properties; however, that synthesized by functionalization of phenol terminated hyperbranched polymers did not increase the toughness as expected.