Synthesis and properties of UV-curable hyperbranched polyurethane acrylate oligomers containing carboxyl groups

Using step by step polymerization process, the first- and second-generation hyperbranched polyesters were synthesized with N,N-diethylol-3-amine methylpropionate as branched monomer and pentaerythrite as a core molecule. The second-generation hyperbranched polyurethane acrylate oligomers containing carboxyl groups were obtained by further reacting with semiadduct urethane monoacrylate and maleic anhydride. The structures of the oligomers were investigated with elemental analysis, FT–IR, and NMR. UV–Vis spectra results showed that the oligomers had sharp absorption bands at about 207 nm. The glass transition temperatures were investigated by differential scanning calorimetry and showed in the range of −44.96 to −19.83 °C. Gel permeation chromatograph was used to observe the molecular weights and polydispersities of the oligomers. UV-curing properties were characterized by FT–IR with different curing time. In addition, the solubilities and viscosity of the oligomers were also examined.