Cyclic Aromatic Polyamides via the Triphenylphosphite Method

5-tert-Butyl-isophthalic acid (TIPA) was polycondensed with three different aromatic diamines by means of triphenylphosphite (TPP) and pyridine. The resulting polyamides were characterized by solution viscosities and MALDI-TOF mass spectra (m.s.). These m.s. revealed significant fractions of cyclic oligo- and polyamides in all samples. In polyamides of high molecular weight, only cycles were detectable (observed up to masses of 13,000Da). Three poly(amide-imide)s were prepared by TPP-mediated polycondensation of trimellitic anhydride (TMA) and three aromatic diamines. Although relatively high molar masses were obtained, the MALDI-TOF m.s. displayed the peaks of linear chains in addition to those of cyclic polymers. The results together suggest that the side reactions mainly occur at the amino endgroups.