Synthesis and Characterization of Poly(amide-ester)s Containing Naphthalene Pendent Groups and Urazole Rings

Abstract

4-(3-Hydroxy-naphthalene)-1,2,4-triazolidine-3,5-dione (3HNTD) was synthesized in six steps starting from 3-hydroxy-2-naphthalene carboxylic acid. The reaction of monomer 3HNTD with acetyl chloride was performed in N,N-dimethylacetamide (DMAc) solution at different molar ratios, and the resulting mono-, di- and trisubstituted derivatives were obtained in high yields and were finally used as models for polymerization reactions. A series of novel aliphatic–aromatic poly(amide-ester)s (PAE)s containing a naphthalene pendent moiety were prepared from 3HNTD and various diacid chlorides (including succinyl chloride, adipoyl chloride and sebacoyl chloride) by polycondensation reactions with three methods: low-temperature solution polycondensation, solution polymerization under gradual heating and reflux conditions in the presence of pyridine and triethylamine as a proton scavenger and without a proton scavenger, respectively. PAEs from aliphatic diacid chlorides and 3HNTD have been studied in great detail via the conventional solution and their synthetic conditions have been optimized to achieve the highest possible molecular weights. In addition to the solubility test, inherent viscosity as a measure of molecular weight was determined. Structural characterization was performed by using infrared (IR), 1H-NMR spectroscopies and elemental analysis. Thermal properties were studied through thermogravimetic (TGA/DTG) thermal techniques. Fluorimetric and UV-Vis studies of the model compounds as well as polymers were performed.