The degradability and thermal properties of chiral polyamide-imides synthesized from several l-amino acids: Side group effects

Abstract

A series of chiral optically active monomers were prepared from l-amino acids with different structures. These monomers were polymerized to chiral polyamide-imides (PAIs) via an eco-friendly direct polycondensation process. The glass transition temperature (Tg) values were obtained by differential scanning calorimetry (DSC), and showed that the rigid and bulk effect of the substituents will co-affect the Tg values of the polymers. Their degradability were studied via soil degradation experiments, and the variations of water contact angles, molecular weights, structure and appearance during degradation were characterized by contact angle tester, gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM) respectively. The results revealed that the damages of polymer chains started with the amide bonds, and then proceed to the imide rings. With degradation, PAI films' hydrophilicity raised, and when introduced amino acids with longer carbon chain or bulky ring into the polymers' backbone, their degradability decreased.