methods. First series of alternate polyamide-imides PAIs-2(a-e) were synthesized from polycondensation of diimide-diacids 1a-1c monomers with various aromatic diamines. Using the direct polycondensation of trimelletic acid chloride (TMAC) with aromatic diamines, second series of polyamide-imides PAIs-3(a-c) were prepared. The effect of monomer sequence on transparency and thermal properties of polymers is investigated. The transmittance at 550 nm (T₅₅₀) from the ultraviolet–visible (UV–vis) spectra of the PAIs was found in the range of 74–87%, greatly affected by the monomer sequence in the polymer repeating units. PAI-3a from TMAC exhibited high transparency of 87% and low coefficient of thermal expansion (CTE) of 25 ppm/K. All copolymers demonstrated good organosolubility and mechanical properties with initial moduli of 3.4–4.9 GPa, tensile strengths of 96–129 MPa and elongations at break of 3.0–5.2%. The glass transition temperatures (Tg) and 10% weight loss temperatures (T10%) of PAIs in nitrogen were in the range of 291–330 ^oC and 489–501 ^oC, respectively.