The preparation of perfectly alternating poly(amide-imide)s via amide unit containing new diamine

The synthesis of N,N'-bis(4'-amino-4-biphenylene) isophthalamide (BABPI) and its applicability as a new diamine for the preparation of a series of new, high T-g, perfectly alternating poly(amide-imide)s is described. BABPI was synthesized from the catalytic reduction of the corresponding dinitro compound which was prepared by the condensation of isophthaloyl chloride and 4-amino-4'-nitrobiphenyl. The modified selective reduction technique was used for the preparation of 4-amino-4'-nitrobiphenyl from 4,4'-dinitro-biphenyl. Poly(amide-imide)s were synthesized by polycon densation of diamine BABPI with various commercially available aromatic dianhydrides via a conventional two-step procedure. In the first step, poly(amic-acid)s were prepared in a polar aprotic solvent, such as N-methyl pyrrolidone (NMP) at room temperature. Depending on the dianhydride used, intrinsic viscosities of poly(amic-acid)s were found to range between 0.43-0.69 dL/g. Bulk thermal imidization technique was used to obtain fully imidized poly(amide-imide)s at the second step. The synthesized poly(amide-imide)s showed good thermal stability up to 320 degrees C and the 10% weight loss temperatures were recorded in the range of 525-550 degrees C as evidenced by thermogravimetric analysis (TGA). The glass transition temperatures were found to be between 225-235 degrees C from differential scanning calorimeter (DSC) measurements. (C) 1997 John Wiley & Sons, Inc.