Cyclic and Linear Polyamides from Polycondensations of Hexamethylenediamine and m-Xylylenediamine with Adipic, Isophthalic, and Terephthalic Acids

Abstract

Cyclic and linear oligoamides were extracted with methanol in 0.1−0.9% yield from condensation polymers of hexamethylenediamine or m-xylylenediamine with mixtures of adipic, isophthalic, and terephthalic acids. The parent polymers and methanol extracts were analyzed using mass spectrometry, and the extracts, in which the smaller molecules were concentrated by a factor of about 200, were studied by nuclear magnetic resonance (NMR) spectroscopy. Small cyclic oligoamides dominated all of the extract spectra. Cyclic monomers were observed with adipic acid but not with the aromatic acids. Cyclic dimers and trimers predominated and yields of higher cyclics decreased rapidly with increasing ring size, especially in the extracts. The degree of incorporation of the acids into small cyclics was adipic > isophthalic > terephthalic. NMR spectra of extracts from all polymers containing terephthalic and/or isophthalic acid units showed linear oligomers with benzoyl end groups, which presumably arose from thermal decarb...