Photopolymerizable acrylated hyperbranched polyisophthalesters used for photorefractive materials: I. Synthesis and characterization

UV-curable acrylated hyperbranched prepolymers with different numbers of acrylic end-groups were synthesized by modifying the hyperbranched polyisophthalester (HPIPE) with hydroxyethyl acrylate and β-naphthol, and characterized by FT-IR, 1H NMR and VPO measurements. The effect of naphthyl end-group concentration of the prepolymer on their refractive index (RI) was investigated by an Abel Refractive Apparatus. It was found that the RI increases gradually as naphthyl end-group concentration increases. The acrylate-modified HPIPEs with or without co-monomer trimethylolpropane triacrylate addition were photopolymerized rapidly in the presence of a photo-fragmenting initiator under UV irradiation. Thermal properties of the UV-cured films were also studied by DMTA and TGA measurements.