Study On Synthesis And Properties Of Polyamide-Imide

1 Polyamide acid was synthesized by polycondensation of trimellitic anhydride chloride (TMAC) and 4,4'-diamino- diphenylether(DDE) in N,N-dimethylacetamide(DMAC), and then converted into polyamide-imide by treating with acetic anhydride and triethylamine mixture. The influence of monomer mass concentration, reaction temperature and monomer ratios on polymer's molecular weight was investigated by FT-IR, 1H-NMR, TGA, DSC, and discussed. It showed that polyamide acid was synthesized at 20℃with mass concentration of 20% and hold 30-40h, then converted into Polyamide-imide by treating with acetic anhydride and triethylamine mixture. The resulting PAI has excellent solvent-resistance and thermal stability. The PAI was solution-cast from DMAC solution into transparent, flexible, and tough film.2 Poly(amide-acid) was synthesized by direct polycondensation of TMAC with aromatic diamine 4,4'-diaminodiphenyl- sulfone (DDS), 4,4'-diaminodiphenylether(DDE) and 4,4'-diamino- diphenylmethane(DDM) in N,N-dimethylacetamide(DMAC) at room temperature, and then converted into poly(amide-imide) by treating with a mixture of acetic anhydride and triethlamine(TEA) . The resulting poly(amide-imide)s have inherent viscosities 0.26-0.89 dL/g. All the polymers were fully characterized by FT-IR spectroscopy, 1H-NMR spectroscopy, and WAXD. The thermal behaviors were studied by Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG), and the mechanical properties of the film were tested by universal testing instrumentation. It showed that these PAIs had glass transition temperatures between 255.97℃- 285.58℃and 5% weight loss temperature (Td) in the range of 425.1℃-455.5℃in air atmosphere. The activity of monomer and mass concentration have effect on molecular weight, and the structure of monomer effected Tg and Td of polymers. Wide-angle X-ray measurement revealed that all the polymers were amorphous. 3 3 ,3′,4 ,4′-tetra-amino-diphenylmethane was synthesized by four steps : the reaction of 4,4'-diamino-diphenylmethane and acetic anhydride, then nitrated into 3,3'-dinitro- 4,4'-diamido- diphenylmethane , after that hydrolyzed to 3,3'-dinitro-4,4'-diamino- diphenylmethane, which by reduction was converted into 3,3',4,4'- tetra-amino-diphenylmethane.The resulting monomer was characterized by FT-IR and ~1H-NMR .