New polyamides based on diacid with decanediamide and methylene groups and aromatic diamines

A new aromatic diacid, containing preformed diamide functional group, C-8 alkylene moiety, and two methylene spacers, viz; N, N '-bis(4 '-carboxy methylene phenyl) decane diamide (BCPDD) was designed and successfully synthesized. The structure of BCPDD was confirmed by FT-IR, NMR (H-1, C-13) spectroscopy and mass spectrometry. The corresponding series of new polyamides were prepared via reactions of diacid (BCPDD) and commercial aromatic diamines by Yamazaki's phosphorylative direct polycondensation method. Physical properties of these polyamides such as inherent viscosity, solubility in organic solvents, glass transition temperatures by DSC, thermal stability by TGA, and amorphous-crystalline mature by XRD were studied. The incorporation of preformed amide, methylene spacers, and C8 alkylene moiety greatly affected polyamide properties such as solubility in common organic polar solvents, glass transition temperature, and thermal stability. These polyamides were mostly amorphous in nature and dissolved in polar aprotic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, m-cresol, and pyridine. Inherent viscosities of these polyamides were in the range of 0.40-0.67dL/g; indicating the formation of moderate to high molecular weights. These polyamides exhibited good thermal stability having temperatures for 10% weight loss (T-10) in the range of 404-578 degrees C and the char yields at 800 degrees C in the range of 35-65%. The glass transition temperatures; as determined by DSC were in the range of 204-235 degrees C.