Silicon-containing halogenated poly(amides) derived from diacids with aminoacidic and imidic moieties in the side chain: synthesis, characterization, optical studies and thermal properties

Abstract

New halogenated silicon-containing poly(amides) (PAs) derived from diacids and an aromatic diamine containing an Si atom were obtained according to the Yamazaki procedure. The diacids contain a preformed halogenated imide ring, another amide group and an aminoacidic residue. The diacids and the PAs were characterized by IR and 1H, 13C and 29Si NMR spectroscopy, elemental analysis and, when corresponding, optical rotation. For those PAs containing F atoms in the imide ring, we also observed the signals corresponding to the coupling of the C–F atoms in the 13C MNR spectra. The results are in agreement with the proposed structures. Also, PAs without amino acid residues were synthesized according to the same procedure. PAs were soluble in aprotic polar solvents and some of them in m-cresol and THF, due to the inclusion in the structure of meta-substitution aromatic rings, flexible aminoacidic residue and polar C–Si bonds. The η inh values were low, indicating the presence of oligomeric species of low molecular weight. The T g values did not show a clear tendency about the influence of the nature of the amino acid residue, but when the influence of the halogen atoms was analyzed, it was possible to observe a decrease in the T g values, due to the higher chain separation, and consequently the lower interactions between them. The thermal decomposition temperatures were determined at 10 % of weight loss, showing in general good values between 300 and 367 °C, and not showing a relationship between the values and the structure of the side groups. The transparency was studied observing moderate values at 400 nm, but showing 80 % of transparency between 500 and 550 nm, which was attributed to the higher aromatic content of these PAs. All PAs showed flame retardancy due to the presence of the halogen atoms.