Pyrimidine based carboxylic acid terminated aromatic and semiaromatic hyperbranched polyamide-esters: synthesis and characterization

Carboxylic acid terminated aromatic and semiaromatic hyperbranched polyamide-esters (HBPAEs) containing pyrimidine moieties were prepared by polycondensation of 4-hydroxy-2,6-diaminopyrimidine (CBB′) to a double molar ratio of various diacid chlorides (A₂) without any catalyst. The products were soluble in organic solvents, such as N,N-dimethylformamide, N-methyl-2-pyrrolidone and displayed glass transition temperature (T_g) between 180 and 244 °C. The polymerization products have been investigated with FTIR, ¹H and ¹³C NMR analyses and the degree of branching was higher than 60%. Amorphous polymers had inherent viscosity (η_inh) ranging between 0.21-0.28 dL/g and had excellent thermal stability with 10% weight loss at 346-508 °C.