Synthesis and characterization of hyperbranched aromatic polyester-imides with good thermal properties based on 1,3,5-tris(3′,4′-carboxyphenyl)benzene trianhydride

A new trifunctional monomer, 1,3,5-tris(3′,4′-carboxyphenyl)benzene trianhydride (TAn), was synthesized and characterized by elemental analysis, FTIR, 1H and 13C NMR spectroscopy. Subsequently, one-step high-temperature polymerization of TAn and a series of commercially available diamine monomers such as p-phenylenediamine (PDA, 1), 4,4′-oxydianiline (ODA, 2), and 1,5-diaminonaphthalene (DAN, 3) successfully yielded wholly aromatic anhydride-terminated hyperbranched poly(ester-imide)s HBPEI 1, 2, and 3, respectively. Gelation was effectively avoided by controlling 1:1 M ratio of A2 and B3 monomers and maintaining total solid content 10 mmol, thereby, producing a novel family of aromatic HBPEIs with inherent viscosities (ηinh) of 0.17-0.28 dL/g. As-prepared HBPEIs were fully characterized by FTIR spectroscopy and were soluble in DMAc, DMSO and NMP. Degree of branching (DB) by 1H NMR analysis of the HBPEIs was estimated to be 0.52-0.56. Differential scanning calorimetry (DSC) showed glass transition temperatures (Tg) between 198 and 208 °C and the synthesized polymers were thermally stable. Furthermore, crystallinity of the polymers was evaluated by means of X-ray diffraction patterns.