New soluble poly(amide-imide-imide)s based on tetraimide-dicarboxylic acid condensed from 4,4′-oxydiphthalic anhydride, 2,2-bis[4-(4-aminophenoxy)phenyl]sulfone, and p-aminobenzoic acid, and various aromatic diamines

A new-type tetraimide-dicarboxylic acid (I) was synthesized starting from the ring-opening addition of p-aminobenzoic acid, 4,4'-oxydiphthalic anhydride, and 2,2-bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS) at a 2:2:1 molar ratio in N-methyl-2-pyrrolidone (NMP), followed by cyclodehydration to the diacid I. A series of poly(amide-imide-imide)s (IIIa (i)) with inherent viscosities of 0.71-0.99 dl/g was prepared by triphenyl phosphite-activated polycondensation from the tetraimide-diacid I with various aromatic diamines (IIa (i)) in a medium consisting of NMP, pyridine, and calcium chloride. All of the polymers were readily soluble in a variety of organic solvents such as NMP, N,N'-dimethyl acetamide, dimethyl sulfoxide, and even in less polar tit-cresol. Compared with those of the corresponding poly(amide-imide)s IVa (i), the solubilities of poly(amide-imide-imide)s IIIa (i); were greatly improved. Most of the polymers III afforded tough, transparent, and flexible films, which had a tensile strength ranging from 94 to 100 MPa, elongation at break from 7 to 9% and initial tensile modulus from 2.0 to 2.3 GPa. The glass transition temperature of polymers was recorded at 265-291 degreesC. They had 10%, weight loss at a temperature above 550 degreesC and left more than 50% residue even at 800 degreesC in nitrogen. (C) 2002 Elsevier Science Ltd. All rights reserved.