New poly(ether-imide)/MWCNT nanocomposite

New polyimide (PI) nanocomposites containing two different amounts of MWCNT (PI/MWCNT) were prepared via in situ polymerization technique. Transmission electron microscopy showed that MWCNT was exfoliated in the polymer matrix, resulting in well-dispersed morphologies at 1 and 3 mass% MWCNT contents. The effects of multiwalled carbon nanotubes (MWCNT) on the thermal and flammability properties of new PI derived from 1,3-bis[4,4′-aminophenoxy]propane and biphenyl dianhydride were investigated by thermogravimetric analysis (TG) in nitrogen and air atmosphere, differential scanning calorimetry, and microscale combustion calorimeter (MCC). The PI/MWCNT nanocomposites were electrically conductive with maximum conductivity obtained at 3 mass% MWCNT, which is favorable for many potential applications. TG results showed that the addition of MWCNT resulted in a substantial increase of the thermal stability and char yields of the nanocomposites compared to those of the neat PI. Flame retardancy of the nanocomposites was significantly improved in the presence of MWCNT.     

Synthesis and characterization of optically active and organosoluble poly(amide-imide)s containing imidazole rings as pendent groups by direct polycondensation

Six new optically active poly(amide-imide)s(PAIs) 6a-f were prepared by direct polycondensation reaction of N-trimelli-tylimido-L-histidine 4 as a chiral diacid with various aromatic diamines 5a-f.Triphenyl phosphite(TPP)/pyridine(Py) in the presence of calcium chloride(CaCl2) and N-methyl-2-pyrrolidone(NMP) were successfully applied to direct polycondensation reaction.The resulting new polymers were in good yields,and had inherent viscosities ranging between 0.29 and 0.41 dL g-1 and were detected with elem...     

Preparation and characterization of new photosensitive and optically active poly(amide-imide)s from N-trimellitylimido-L-amino acid and dibenzalacetone moiety in the main chain

Six new photosensitive and optically active poly(amide-imide)s 8a–8f with good inherent viscosities based on dibenzalacetone moiety were synthesized from the direct polycondensation reaction of N-Trimellitylimido-L-amino acids 3a–3f with 2,5-bis(4-aminobenzylidene)cyclopentanone 7 by two different methods such as direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone/triphenyl phosphite/calcium chloride/pyridine and direct polycondensation in a tosyl chloride/pyridine (py)/N,N-dimethylformamide system. Diamine 7 was synthesized by using a two-step reaction. At first 2,5-bis(4-nitrobenzylidene)cyclopentanone 6 was prepared from the reaction of two equimolars 4-nitrobenzaldehyde 5 and one equimolar cyclopentanone 4 and dinitro compound 6 was reduced by using Na2S. Also N-trimellitylimido-L-amino acids 3a–3f were synthesized by the condensation reaction of trimellitic anhydride 1 with two equimolars of various L-amino acids 2a–2f in an acetic acid solution. The polymerization reactions produced a series of photosensitive and optically active poly(amide-imide)s with high yield and good inherent viscosity. The resulted polymers were fully characterized by means of FTIR and ¹H-NMR spectroscopy, elemental analyses, inherent viscosity, specific rotation, solubility tests, UV-VIS spectroscopy, differential scanning calorimeter, thermogravimetric analysis, and derivative of thermogravimetric. These macromolecules exhibited maximum UV-VIS absorption at around 395 and 265 nm in a N,N-dimethylformamide solution.     

Preparation of new poly(ether-amide-imide)s from 1,4-bis-[4-(trimellitimido)phenoxy]butane and aromatic diamines via direct polyamidation

Several new Poly(ether-amide-imide)s were prepared by direct polycondensation reactions of 1,4-bis-[4-(trimellitimido)phenoxy]butane with various aromatic diamine. Two direct polycondensation techniques were used: direct polycondensation in a medium consisting of N-methyl-2-pyrrolidone/triphenyl phosphite/calcium chloride/pyridine and direct polycondensation in a tosyl chloride/pyridine/N,N-dimethylformamide system. All the monomers and polymers were fully characterized by means of FTIR, ¹H-NMR spectroscopy and elemental analyses and properties of the polymers including solution viscosity, thermal behavior and solubility were studied.