Synthesis of highly transparent poly(amide-imide)s based on trimellitic acid and dependence of thermal properties on monomer sequence

Transparent, thermally stable, and semiaromatic poly(amide-imide)s were prepared from hydrogenated trimellitic anhydride chloride (h-TAC) with various aromatic diamines. The dependence of thermostability on the monomer sequence and terminal group was investigated. Thermogravimetric/differential thermal analysis (TG/DTA) was performed to evaluate the thermostabilities, which were found to be primarily affected by the monomer sequence in the polymer units. The 5% weight loss temperature (Td5) in N2, glass transition temperature (Tg), and cutoff wavelength of the ultraviolet-visible (UV-Vis) spectrum (λcut) of the semiaromatic poly(amide-imide)s are 422-456 °C, 131-274 °C, and 293-321 nm, respectively, while those of wholly aromatic poly(amide-imide)s are 454-480 °C, 169-287 °C, and 415 nm, respectively.