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 293–321nm, respectively, while those of wholly aromatic poly(amide–imide)s are 454–480°C, 169–287°C, and 415nm, respectively.