Synthesis and characterization of low viscosity aromatic hyperbranched polyester epoxy resin

Low viscosity aromatic hyperbranched polyester epoxy resin (HTBE) was synthesized by the reaction between epichlorohydrin (ECH) and carboxyl-end hyperbranched polyester (HTB) which was prepared from inexpensive materials A2 (1,4-butanediol glycol, BEG) and B3 (trimellitic anhydride, TMA) by pseudo one-step method. The molar mass of the HTB was calculated from its acid value by “Recursive Probability Approach”. The degree of branching (DB) of the HTB was characterized by model compounds and1H NMR-minus spectrum technology, and the DB of the HTB was about 0.47∼0.63. The viscosity and epoxy equivalent weight of the HTBE were 3,600∼5,000 cp and lower than 540 g/mol respectively. The reaction mechanism and structure of the AB2 monomer, HTB and HTBE were investigated by MS,1H NMR and FTIR spectra technology. The molecular size of HTBE is under 8.65 nm and its shape is ellipsoid-like as determined by molecular simulation.