Synthesis and biodegradation studies of optically active poly(amide–imide)s based on N , N ′-(pyromellitoyl)-bis- l -amino acid

Five new optically active poly(amide–imide)s (PAIs) (PAI3a–PAI3e) were synthesized through the direct polycondensation reaction between chiral N, N′-(pyromellitoyl)-bis-l-amino acids and 4,4′-diaminodiphenyl ether. The resulted polymers were fully characterized by means of Fourier transform infrared (FTIR) and proton nuclear magnetic resonance spectroscopy, elemental analysis, inherent viscosity measurement, solubility tests, specific rotation, and thermogravimetric analysis (TGA). The biodegradation studies of the PAIs were performed in soil and in phosphate buffer solution. The surface morphology and hydrophobicity of the biodegraded PAI films were investigated. FTIR spectra showed structural changes on PAI powders being treated in phosphate buffer solution. The TGA data showed that the thermal stability of PAI powders decreased with the degradation time. The collected degradation products were soluble in water and had absorption in ultraviolet and visible light region. Possible biodegradation mechanism of amino acid-based PAIs was explored.