Expeditious synthesis of novel aromatic polyamides from 5-[3-phenyl-2-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)propanoylamino]isophthalic acid and various diamines using microwave-assisted polycondensation

A new diacid monomer, 5-[3-phenyl-2-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)propanoylamino]isophthalic acid was successfully synthesized starting from cis-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylic acid anhydride and l-phenylalanine. A highly effective, very fast microwave method is described to synthesize optically active aromatic polyamides (PA)s under microwave heating for only 3 min. Generally, better yields are obtained under faster and cleaner reactions when compared to those from conventional heating. Therefore, this approach could considerably reduce the synthesis time, cost, and energy. The resulting PAs had inherent viscosities in the range of 0.35-0.58 dL/g. All of the these polymers having bulky anthracenic and amino acid functionality in the side chain showed excellent solubility and readily dissolved in various solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide and N,N-dimethylformamide. PAs were thermally stable, with 10% weight loss recorded at 385 °C and 341 °C in the nitrogen atmosphere, and char yields at 800 °C higher than 50% and glass transition temperature above 180 °C.