Synthesis And Characterization Of Optically Active Poly(amide-imide)s

Optically active polymers derived from amino acids are a very active research in polymer materials. They have broad application prospect in chiral catalysts, chiral LCDs, nonlinear optical materials and Biological medicine, etc.In this paper, a series of chiral imide diacids monomers were synthesized by condensation reaction of 3,3′-4,4′-biphenyl tetracarboxylic acid dianhydride (BPDA) with L-alanine, L-valine etc. natural chiral amino acids and D-alanine, D-benzene glycine in acetic acid. The monomers were obtained in quantitative yield, and were characterized by DSC, ¹H-NMR,¹³C-NMR and elemental analysis etc.The PAIs were synthesized by high-temperature solution polycondensation used these diacids reacted with PPD, ODA or MDI in polar aprotic solvents. The resulting new polymers were characterized by FT-IR, 1H-NMR spectroscopy and specific rotation. TGA and DSC study indicated that some of the polymers have good thermostability, T_d5%>350℃, T_d10%>380℃. Moreover amino acid groups of the polymers improve their solubility, and these PAIs showed better solublility in polar aprotic solvents such as N,N-dimethylformamide(DMF), dimethylsulfoxide (DMSO), N-methyl pyrrolidone (NMP).Experimental results showed that the better method is the direct phosphorylation polycondensation reaction of chiral diacid with various aromatic diamines by using Triphenyl phosphite (TPP)/pyridine (Py) as condensingagent in the presence of calcium chloride (CaCl₂) and N-methyl-2-pyrrolidone.These synthesised PAIs have similar thermal stability and better solubility compared with the other PAIs. The polymers with optically activity, biocompatibility and biodegradability, have more widely application.