Synthesis and properties of novel poly(ester-amide-imide)s containing pendant phthalimide substituent

Two series of novel poly(ester-amide-imide)s (PEsAIs) with pendant phthalimide side group were synthesized by copolymerization of phthalimide-hydroquinone bis(trimellitate anhydride) (PI-TAHQ), p-phthaloyl chloride (TPC) and other fluorinated monomers using the two-step method. These PEsAIs had glass transition temperatures (Tgs) in the range of 228 degrees C-296 degrees C and coefficients of thermal expansion (CTEs) of 18-55 ppm center dot K-1. These films had good mechanical properties with tensile modulus of 3.7-5.7 GPa, tensile strengths of 92-153 MPa and elongations at break of 2.2%-8.3%. All films displayed good transparency with transmittances at 400 nm (T400nm) of 43%-79% and transmittances at 850 nm (T850nm) exceeding 89%, and these PEsAIs were amorphous. Especially, PEsAI-d-60 presented the best comprehensive performance with Tg of 296 degrees C, low CTE of 18 ppm center dot K-1 and high transmittance (T400nm of 79%, T850nm of 91%), which exhibited the potential of this novel poly(ester-amide-imide) containing pendant phthalimide substituent in optical transparent materials.