Synthesis, characterization and corrosion inhibitive properties of new thiazole based polyamides containing diarylidenecyclohexanone moiety

Abstract

The present work aimed to synthesize a new interesting series of thiazole based polyamides containing diarylidenecyclohexanone moiety 5 a-5 f using low temperature solution polycondensation technique. The new polymers were synthesized by the reaction of thiazole based monomer namely, bis(2-aminothiazol-4-ylbenzylidene)cyclohexanone 3 with different aliphatic and aromatic diacid chlorides using NMP, and in the presence of anhydrous LiCl as catalyst. Adipoyl, sebacoyl, oxaloyl, terephthaloyl, isophthaloyl dichlorides and biphenyl dicarbonyl dichloride were used as diacid chlorides. The structure of the model compound 4 as well as the new polymers was confirmed by correct elemental and spectral analyses. The thermal properties of those polymers were evaluated by TGA and DTG measurements and correlated to their structural units, beside X-ray diffraction analysis, solubility and viscometry measurements. The inherent viscosities for the synthesized polymers were in the range 0.6–1.03 dL/g. On the other hand the corrosion inhibitive properties of monomer 3 as well as polyamides 5 d and 5 f as selected examples were carried out on carbon-steel in 0.5 mol/L H2SO4 at 40 °C. The calculated inhibition efficiency (IE%) for polymer 5 d was in the range (82 ± 6)% in all selected concentrations. The best value of IE% was obtained at 1 mg/L to reach 98.24% for polymer 5 d and at 0.5 mg/L to reach 87.75% for polymer 5 f.