Six new poly(amide-imide)s (PAIs) 8a-f were synthesized from the direct polycondensation reaction of 1,1-bis[4-(trimellitimido)phenoxy]methane 6 with various aromatic diamine 7a–f. The polymerization reactions produced a series of thermally stable and organosoluble PAIs 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, and solubility tests. Also thermal properties of the PAIs 8a–f were investigated using thermal gravimetric analysis (TGA) and derivative of thermaogravimetric (DTG) analysis. dicarboxylic acid 6 was synthesized from the reaction of 1,1-bis[4-aminophenoxy]methane 4 with trimellitic anhydride 5 in a solution of glacial acetic acid/pyridine (Py) at refluxing temperature.

A new-type of dicarboxylic acid 6 was synthesized from the reaction of 1,4-bis[4-aminophenoxy]butane 4 with trimellitic anhydride 5 in a solution of glacial acetic acid/pyridine (Py) at refluxing temperature. 1,4-Bis[4-nitrophenoxy]butane 3 was prepared by reaction of 4-nitrophenol 1 with 1,4-dibromo butane 2 in N,N-dimethylformamide (DMF) solution. Then dinitro 3 was reduced to 1,4-bis[4-aminophenoxy]butane 4 by using 10% Pd–C, ethanol, and hydrazine monohydrate. So six new thermally stable and organosoluble poly(ether–ester–imide)s (PEEIs) 8a–f with good inherent viscosities were synthesized by the direct polycondensation reaction of new 1,4-bis[4-(trimellitimido)phenoxy]butane 6 with several aromatic diols 7a–f through direct polycondensation using tosyl chloride (TsCl)/pyridine (Py)/DMF system as condensing agent. The resulted polymers were fully characterized by means of FTIR and ¹H NMR spectroscopy, elemental analyses, inherent viscosity, solubility tests, differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and derivative of thermogravimetric (DTG).

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.

A catalyst-free conjugate addition of dithiocarbamic acid salts to in situ generated ortho-quinone methides (o-QMs) was investigated for the first time. Several dithiocarbamate derivatives of 4-hydroxycoumarine, 4-hydroxypyrone and 2-naphthol were synthesized in moderate-to-good yields in water at room temperature.

Graphical abstract

Catalyst-free addition of dithiocarbamic acid salts to in situ generated o-QMs in water at room temperature.

Five new optically active polyamides (PAs) 6a–6e were prepared by direct polycondensation reaction of 2-(1,3-isoindolinedione-2-yl)-glutaric acid 4 as a new chiral diacid with various aromatic diamines 5a–5e in a medium consisting of triphenyl phosphite (TPP), calcium chloride, pyridine (Py) and N-methyl-2-pyrrolidone (NMP). The polycondensation reaction produced a series of polyamids 6a–6e in quantitative yields with inherent viscosities of 0.26–0.39 dL/g. The resulting polymers were fully characterized by means of 1H-NMR, FT-IR spectroscopy, elemental analysis, inherent viscosity and specific rotation. Thermal properties of these polymers were investigated using thermal gravimetric analysis (TGA) and differential thermal gravimetry (DTG). Phthalimide rings as a bulky pendent group in the polymer chains disturb the interchain and intrachain interactions and make these PAs readily soluble in polar, aprotic solvents such as N,N-dimethyl acetamide (DMAc), N,N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP) and sulfuric acid.

The new aromatic polyamides containing α-amino phosphonate were synthesized from phosphorus-based dicarboxylic acid 4 and various aromatic diamines by direct polycondensation reaction. Dicarboxylic acid 4 was successfully synthesized from trimethyl phosphite, 4-aminobenzoic acid and terephthaldehyde via a three-component reaction. The polymerization reaction produced the polyamides 6a–f with high yield and desirable inherent viscosities. The thermal properties of the all samples were investigated by thermo-gravimetric analysis (TGA). The TGA results in N₂ exhibited the 10% mass loss temperatures (T₁₀) in the ranges of 324–345 °C, while the T₁₀ resulted from thermo-oxidative degradation were higher than those. The main data obtained by microscale combustion calorimetry revealed acceptable combustion properties such as very low peak of heat release rate for the synthesized polyamides 6a–f. The all of the results indicated that these polyamides can be potentially utilized as additive for improvement of thermal resistance and combustion behavior of thermoplastic materials.

In this research, a fast, simple, selective, and sensitive spectrophotometric method based on dispersive liquid–liquid microextraction (DLLME) was developed for the ultratrace determination of copper(II) using newly synthesized chromogenic reagent (4-hydroxy-2-oxo-2H-chromen-3-yl)methyl pyrrolidine-1-carbodithioate (HCDTC). The affecting factors in complexation and microextraction steps were investigated and optimized. HCDTC forms highly sensitive yellow-colored complex with copper(II) (1:4 [copper(II): ligand]) in the wide pH range which shows maximum absorbance at 445 nm. In direct determination, Beer’s law was obeyed in the concentration range from 0.1 to 5.0 mg L⁻¹. Molar absorptivity and Sandell’s sensitivity values for Cu(II)–HCDTC complex were 1.3 × 10⁴ and 0.0047 µg cm⁻², respectively. However, by applying DLLME, a detection limit as low as 0.3 µg L⁻¹ with preconcentration factor of 92 and relative standard deviation (n = 6) less than 3.5% were achieved. Moreover, calibration graph was linear in the range of 1.0–200 µg L⁻¹. Finally, the proposed method was successfully applied for preconcentration and determination of the Cu(II) in some water and fruit juice samples, and satisfactory results were obtained. Accuracy and reliability of the method were also verified by GF-AAS.

In this study a new series of magnetic and heat resistant nanocomposites were prepared based on a highly soluble poly(imide-ether) (PIE) reinforced with two different types of magnetic nanoparticles via a solution intercalation technique. New PIE with good solubility and desired molar mass containing bulky xanthene rings and amide groups in the side chains was synthesized via thermal cyclization of the poly(amic acid) precursor, obtained from the reaction of a new diamine derived from 9H-xanthene and 4,4′-oxydiphthalic dianhydride (ODPA). Improved solubility was attributed to the presence of xanthene group and flexible ether linkage in the polyimide backbones that reduce the chain-chain interaction and enhance solubility by penetrating solvent molecules into the polyimide chains. Fe₃O₄ nanoparticles (MNPs) which synthesized from chemical co-precipitation route were coated with silica (SiO₂), sequentially with (3-aminopropyl)triethoxysilane and poly-melamine-terephthaldehyde (MNPs-PMT), and then separately dispersed in the poly(amic acid) solutions and thermally imidized to form PIE/Fe₃O₄ and PIE/MNPs-PMT nanocomposites. The nanostructures and properties of the resultant materials were investigated using FTIR spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The properties of the nanocomposites were strongly related to the dispersion and interaction between the nanoparticles and PIE matrix. The thermogravimetric analysis (TGA) results showed that the addition of MNPs-PMT nanoparticles resulted in a substantial increase in the thermal stability of the corresponding PIEN. The temperature at 10% weight loss (T₁₀) was increased from 416 °C to 428 °C for PIEN containing 3 wt% MNPs-PMT as compared to neat PIE, as well the char yield enhanced. Furthermore, the MNPs-PMT nanoparticles had better dispersion in the polymer matrix due to the strong intermolecular hydrogen bond interactions between the NH and C=N groups of surface-modified nanoparticles and the PIE matrix than the uncoated Fe₃O₄ nanoparticles, and exhibited a better intercalated morphology and improved thermal properties. Also, the PIEN nanocomposites under applied magnetic field exhibited the hysteretic loops of the superparamagnetic nature.

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.

New type of nanocomposite materials were produced using a poly(amide-imide) (PAI) matrix and novel organoclay as a reinforcing agent by solution intercalation technique in N-methyl-2-pyrrolidone (NMP). The organoclay was prepared from Cloisite Na⁺ and protonated form of bis(3-amino phenyl)phenyl phosphine oxide via ion-exchange reaction. It was confirmed by Fourier transform infrared spectroscopy and X-ray powder diffraction techniques. A new PAI containing phenylacetic acid moiety was synthesized by direct polycondensation reaction of 2,2′-(5,5′-oxybis(1,3-dioxoisoindoline-5,2-diyl))bis(2-phenylacetic acid) as a new diacid and 4,4′-diaminodiphenylsulfone. Poly(amide-imide)/nanocomposites (PAIN)s containing 4 and 8 % of new organoclay were prepared via solution intercalation method through blending of organoclay with the PAI solution. The nanostructures and properties of the PAINs were investigated using different techniques. Transmission electron microscopy and XRD results revealed the good dispersion nano silicate layers in the polymer matrix. Thermal properties and flame retardancy of the resulting PAINs were investigated by thermal gravimetry analyses and microscale combustion calorimetry techniques. Organoclay shows a good effect on improving the flame retardancy of the PAI, reflecting the decrease in heat release rate (HRR) from 250 W/g for PAI to 185 and 157 W/g for PAINs, while the thermal stability of the PAI nanocomposites only increased slightly compared to the neat polymer.