Synthesis and properties of hyperbranched polyesters with diol as a core monomer

The third generation hyperbranched polyesters (HBPs) were synthesized by the pseudo-one step method with 2, 2-bis(hydroxyl-methyl) propionic acid as AB2 monomer, p-toluene sulfonic acid as catalyst, in which 2-butyl-2-ethyl-1, 3-propanediol (BEPD, HBP-1), 1, 4-butanediol (BDO, HBP-2), and neopentyl glycol (NPG, HBP-3) were used as the core monomers, respectively. The structures and molecular weights of HBPs were characterized with FT-IR, NMR and GPC as well as their intrinsic viscosities were also given. The film properties of HBPs cured by the toluene diisocyanate adduct were tested. The thermal stability of cured HBPs films were also examined by thermogravimetric analysis (TGA). It was found that HBPs are successfully synthesized and HBP-1 displays the highest branching degree up to 0.55. The GPC measured molecular weights of HBPs approach to the theoretical values, and HBP-1 exhibits the lowest polydispersity index up to 1.68. HBPs are soluble in strong polar solvents and insoluble in non-polar solvents and HBP-1 displays better solubility and lower intrinsic viscosity up to 4.24 mL · g-1. The cured HBPs films exhibit good thermal stability, adhesion, flexibility, and high hardness.