Synthesis And Properties Of Novel Poly(Amide-Imide)

In this thesis, a new type of poly(amide-imide)s (PAIs) were prepared by biobased renewablecitric acid (CA) and succinic acid (SA) with solvent-free polymerization. Water-solublepolyamides (PAs) containing carboxyl side chain were prepared by ring opening of the imidethrough the hydrolysis of PAIs in alkaline solution. The structures of PAs are found to be similar topolyaspartic acid (PASP), as verified by NMR spectroscopy.In the second chapter of this thesis, PAIs were synthesized by CA and hexanediamine(HMDA) with different ratios. The structure and properties of the obtained poly(citramide-imide)PAIs were analyzed and characterized by FTIR, Raman, XRD, DMA, DSC and TGA techniques.The densities and water absorption were also measured. The results show that, PAIs exhibit highthermal stability and good hydrophilicity. They have two glass transition temperatures (Tg),corresponding to the structure of amide and imide, respectively. GPC was used to measure themolecular weight of hydrolyzed PAs. In addition, the chelation capabilities of hydrolyzed PAs formetal ions were examined. The best product has a chelating capability of191.6mg/g toward Ca2+and950.5mg/g toward Pb2+, which is much better than the commercial sequesters.In the third chapter of this thesis, SA and HMDA at equimolar ratio were used to synthesizepolysuccinamide PA firstly, then CA, SA and HMDA with different ratios were used to synthesizepoly(citramide-imide-co-succinamide)s. The structure and crystallinity of the obtained copolymerswere analyzed by FTIR and XRD. The results show that, the ordered structure is destroyed due tothe imide structure, so the crystallinity of copolymers is lower than that of PA. Also two Tghavebeen detected by DMA. Mechanical properties of copolymers were measured. The maximumtensile strength can reach73.05MPa and the maximum elongation at break can be up to26.09%.The hydrolyzed PAs also exhibit excellent chelating abilities to Ca2+and Pb2+. The thermalbehavior during the thawing of the aqueous solution of PAs was recorded by DSC. The freezingpoint decreasing to below0°C obviously and the depression of the ice fraction of these frozenwater indicate that PAs have antifreeze ability, which inhibit the freezing of solution.In the fourth chapter of this thesis, a new type of hyperbranched polycitramide PAs wereprepared by CA and ethylenediamine (EDA) with different ratios, providing a new method fordirect synthesis of water soluble PA. The structure of the product was characterized by FTIR. Theantifreeze activity of the hyperbranched PAs was also inspected by DSC. The result shows that, thehyperbranched PAs have much better antifreeze activities in inhibiting the ice formation than the widely used PASP and glucose, and nearly the same as the PAs hydrolyzed from PAIs in alkalinesolution. The hyperbranched PAs and hydrolyzed PAs prepared from PAIs may offer promise asnew types of natural gas hydrate inhibitors.