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New crosslinked polyamides were successfully produced from the condensation of pre‐synthesized monomer, 5‐(2,2,2‐trifluoroacetamido)isophthaloylchloride (TFAIAC) and diamines at low temperature. These polyamides were used as promising metal‐chelating adsorbents due to the presence of O and N donor sites on the crosslinked polyamides. For this purpose, trifluoroacetic anhydride was used to protect the amino group of 5‐aminoisophthalic acid, thus generating 5‐(2,2,2‐trifluoroacetamido)isophthalic acid (TFAIA). TFAIA was converted into TFAIAC using oxalyl chloride, which was exploited as a suitable monomer for the synthesis of aromatic polyamides. Amino groups were then set free under basic conditions and the crosslinking was carried out through amino groups present on the polyamide chains with different dianhydrides, isophthaloyl chloride and 2,5‐thiophenedicarboxaldehyde. The synthesis of monomers and polymers was confirmed by Fourier transform infrared, 1H and 13C NMR spectroscopy and molar masses of the polyamides were measured by gel permeation chromatography. The crosslinked macromolecules were found to possess enough chain alignment as depicted by their XRD patterns. The thermal stability of the crosslinked polyamides was increased as their decomposition temperatures were improved from 420 to 619 °C. Metal ion uptake was scrutinized through atomic absorption spectroscopy with 83%–85% adsorption capacity at optimized parameters, i.e. a contact time of 3 h at pH 6. The mechanism of adsorption was further investigated through the Freundlich and Langmuir adsorption isotherms. The results reveal that uptake of metal ions followed monolayer adsorption of cations owing to coordination to electronegative centers on the macromolecules, confirming the Langmuir adsorption model. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Nanocomposites were synthesized from polyamide and aminosilane functionalized montmorillonite through solution intercalation method. Polyamide resin was prepared by reacting a mixture ofp-phenylenediamine and 4,4′-oxydianiline with isophthaloyl chloride (IPC) inN,N′-dimethyl acetamide (DMAc) under anhydrous conditions. The resulting chains were end capped with carbonyl chloride using slight excess of IPC near the end of reaction. 3-Aminopropyltriethoxysilane (APTS) was used for the surface modification of clay. Triethoxysilane groups of APTS promoted the reaction between silane and hydroxyl groups on the surface of clay. The compatibility between the two disparate phases was achieved through interaction of free amine groups of modified clay with carbonyl chloride of the matrix. Thin films obtained by evaporating the solvent were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), and tensile measurements. XRD and TEM results revealed the formation of partially delaminated and intercalated clay platelets in the matrix. Mechanical data showed improvement in the tensile strength and moduli of the nanocomposites with clay loading up to 6 wt.%. The glass transition temperature increased up to 134°C for the nanocomposites containing 6 wt.% clay content and also the thermal stability augmented with increasing clay loading. [ABSTRACT FROM PUBLISHER]

The generation of supramolecularly organized structures from intermolecular interaction motivated us to fabricate new miscible nanoblends of polymethylmethacrylate (PMMA) and aramid. The polyamide, prepared through the condensation of 1,5-diaminonaphthalene and 1,4-phenylenediamine with isopthaloyl chloride, was incorporated into PMMA matrix to produce completely miscible nanostructured blends via physical interlocking. The influence of polymer-polymer interaction on the macroscopic properties of blends were studied using mechanical testing, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. Ample adhesion between the blend components revealed higher tensile strength in the range 51-58 MPa. The physical interaction of PMMA with varying aramid content altered blend morphology significantly, i.e. from ellipsoidal to circular realms having well-defined boundaries and knitted nanofibril network. Blends with 10-70 wt% aramid, thus, possessed exclusive patterns owing to nanolevel compatibility between two phases. Differential scanning calorimetry results also designated exclusively miscible blends with glass transition between 67-81°C, lower than that of pristine polymers. Ten percent gravimetric loss temperature (T10) increased from 465°C to 531°C with increasing aramid content from 10 to 70 wt%. Novel nanoblends holding spherical/cylindrical supramolecular arrangement, easy processing, and thermal and mechanical integrity can be potentially favorable in many industrial applications. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The novel difunctional monomer, 1-(4-aminobenzoyl)-3-(3-aminophenyl) thiourea (ABAPT), was synthesized by the reduction of NBNPT (1-(4-nitrobenzoyl)-3-(3-nitrophenyl) thiourea). The characterization of the monomers was carried out using spectroscopic and elemental analyses. A series of novel aromatic and aromatic-aliphatic poly (thiourea-amide)s (PAMDs) were obtained through the condensation of ABAPT with various diacid chlorides (terephthaloyl, isophthaloyl, sebacoyl and adipoyl chloride). Structural elucidation of the resulting polyamides was carried out by FTIR, 1H- and 13C-NMR techniques along with solvent miscibility, viscosity, molecular weight, crystallinity, non-flammable and thermal studies. The polymers bearing phenylthiourea moieties in the backbone were obtained in quantitative yield. PAMDs having inherent viscosities of 1.02-1.32 dL g−1 exhibited good organosolubility in amide solvents (N,N-dimethylacetamide, dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone). X-ray diffraction studies specified crystalline behavior of new polyamides. Gel permeation chromatography measurements disclosed Mw around 34 000-65 000. The thermogravimetric analyses and limiting oxygen index measurements indicated that aromatic polyamides were stable up to 500 °C and were adequately flame retardant. Moreover, their glass transition temperatures were found to be 265-273 °C. [ABSTRACT FROM PUBLISHER]

Abstract: Surface treated montmorillonite was used to prepare nanocomposites with aromatic–aliphatic polyamide by solution intercalation technique. The polyamide chains were produced through polycondensation of 4-aminophenyl sulfone with sebacoyl chloride in dimethyl acetamide. Compatibility between the polymer and organoclay was achieved through carbonyl chloride end-capped amide chains prepared by adding extra sebacoyl chloride near the end of polymerization reaction. The nanocomposites morphology and clay dispersion were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Delaminated and intercalated morphologies were observed for different loading of organoclay. Tensile strength and modulus improved for nanocomposites with optimum organoclay content (10-wt.%). Thermal stability and glass transition temperature of nanocomposites increased relative to pristine polyamide with augmenting organoclay content. Water uptake of these materials decreased as compared to the neat polyamide indicating reduced permeability. [Copyright &y& Elsevier]

Transparent sol–gel-derived nanocomposites were prepared by incorporating an alumina network into a polyamide matrix. Different amounts of aluminum butoxide were hydrolyzed and condensed to produce the alumina network. Thin composite films were characterized in terms of their optical, morphological, mechanical and thermomechanical properties. Tensile modulus, stress at both yield and break points, improved for alumina loadings of 5–10wt.%. The glass transition temperature increased to 140°C for nanocomposites containing 15wt.% alumina. Scanning electron microscopy investigations indicated a uniform distribution of alumina in the polyamide matrix. [Copyright &y& Elsevier]

Nanocomposites were synthesized from reactive thermally stable montmorillonite and aromatic–aliphatic polyamide obtained from 4-aminophenyl sulfone and sebacoyl chloride. Carbonyl chloride terminal chain ends were generated using 1% extra sebacoyl chloride that could interact chemically with the organoclay. The distribution of clay in the nanocomposites was investigated by XRD, SEM, and TEM. Mechanical and thermal properties of these materials were monitored using tensile testing, TGA, and DSC. The results revealed delaminated and intercalated nanostructures leading to improved tensile strength and modulus up to 6 wt% addition of organoclay. The elongation at break and toughness of the nanocomposites decreased with increasing clay contents. The nanocomposites were thermally stable in the range 400–450 °C. The glass transition temperature increased relative to the neat polyamide due to the interfacial interactions between the two phases. Water uptake of the hybrids decreased upon the addition of organoclay depicting reduced permeability. [ABSTRACT FROM AUTHOR]

New soluble and linear aromatic polyamide chains were produced by condensing 4-aminophenylsulfone with isophthaloyl chloride in dimethylacetamide as a solvent under an inert atmosphere. HCl produced as a byproduct was removed from the reaction mixture by precipitating with a stoichiometric amount of triethylamine. A clear polyamide solution was obtained after isolation of the precipitates. Thin and transparent film was cast from the solution by baking out the solvent and after drying, the film was employed for various analyses. It was found to be soluble in various organic solvents. The structure elucidation of the resulting polyamide was carried out using infrared and nuclear magnetic resonance spectroscopy. The molecular weight distribution was determined by gel permeation chromatography. These results confirmed the formation of the aromatic polyamide. Thermogravimetry, differential scanning calorimetry, water absorption and mechanical measurements were also performed to further verify the physical properties of the aromatic polyamide. [ABSTRACT FROM AUTHOR]

Aromatic polyamide was synthesized via condensation polymerization of 4-aminophenyl sulfone (APS) with isophthaloyl chloride (IPC) using N, N-dimethyl acetamide (DMAc) as a solvent under anhydrous conditions. The purified aramid was studied by laser light scattering (LLS) in dimethyl sulfoxide (DMSO), a thermodynamically good solvent at 20°C. Static and dynamic light scattering studies permitted to determine the weight average molecular weight $\langle {M_{\rm w}}\rangle $, radius of gyration $\langle {R_{\rm g}}\rangle $, second virial coefficient A2, the hydrodynamic radius RH, and the diffusion coefficient D. Light scattering experiments were conducted at five concentrations ranging from 0.27 to 2.5 g/L. LLS measurement is also a very useful technique to study the aggregation or association in a polymer system as long as the large 'clusters' are reasonably stable in time. The intensity autocorrelation function obtained on the quasi-elastically scattered light showed a simple diffusive relaxation mode. The ratio of radius of gyration to the hydrodynamic radius, i.e. $\langle {R_{\rm g} }\rangle /\langle {R_{\rm H}}\rangle $ ∼ 1.3 indicates that the polyamide chain has coil conformation in DMSO at 20°C. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article presents the results of research on the use of the solution intercalation method to create nanocomposites from aromatic polyamide and montmorillonite. Isophthaloyl chloride was reacted with 4,4-oxydianiline in N,N -dimethyl acetamide to form aramid chains. A high-speed mixer was used to disperse the organoclay throughout the polymer solution. The solvent was evaporated and thin films were cast from the resulting materials. X-ray diffraction and measurements of thermal and mechanical properties were used to characterize them.

Aramid-based nanocomposites were prepared by solution intercalation techniques using p-aminobenzoic acid-modified montmorillonite. Polyamide was synthesized by reacting 4,4'-oxydianiline with isophthaloyl chloride in dimethyl acetamide. To create chemical interactions between the two phases for better dispersion of organoclay, aramid chains were selectively amine end-capped. The influence of organically modified clay on the morphology was investigated by x-ray diffraction (XRD), polarized optical microscopy (POM), and transmission electron microscopy (TEM). Mechanical, thermal, and water uptake measurements were carried out to further verify other physical properties of the nanocomposites. Tensile strength, modulus, elongation at break, and toughness were improved relative to pure polymer with the addition of 6 wt% organoclay. Thermal-decomposition temperatures of the nanocomposites were in the range 300-450 °C. Water uptake of neat aramid film was rather high (5.7%) and decreased with augmenting organoclay. DSC exhibited increase in the glass transition temperature (118 °C) up to addition of 16 wt% of organoclay. [ABSTRACT FROM AUTHOR]

Aminosilane grafted and diamine modifiedreactive montmorillonitewas exploited to generate aromatic polyamide based nanocomposites.For better compatibility, the hydrophilic nature of montmorillonitewas changed into organophilic using 1,4-phenylenediamine, and thehydroxyl groups present on the clay surface and edges were used tograft 3-aminopropyltriethoxysilane (APTS) on clay sheets. The dispersionof clay was monitored in the polyamide obtained from 1,4-phenylenediamine,4,4′-oxydianiline, and isophthaloyl chloride. These chainswere converted into carbonyl chloride ends to interact with free aminegroups of grafted APTS and diamine. Thin films were probed for FTIR,XRD, SEM, TEM, tensile testing, TGA, and DSC measurements. The resultsdescribed ample dispersion of clay in the nanocomposites with tensilestrength increased 110% and elongation increased 172% upon the additionof 4–6 wt % clay. Thermal decomposition temperatures of thenanocomposites were in the range 425–480 °C. The glasstransition temperature increased up to 142.4 °C with 6 wt % additionof organoclay. [ABSTRACT FROM AUTHOR]

Abstract: Carboxylic acid terminated aromatic and semiaromatic hyperbranched polyamide-esters (HBPAEs) containing pyrimidine moieties were prepared by polycondensation of 4-hydroxy-2,6-diaminopyrimidine (CBB′) to a double molar ratio of various diacid chlorides (A 2) without any catalyst. The products were soluble in organic solvents, such as N,N-dimethylformamide, N-methyl-2-pyrrolidone and displayed glass transition temperature (T g) between 180 and 244°C. The polymerization products have been investigated with FTIR, 1H and 13C NMR analyses and the degree of branching was higher than 60%. Amorphous polymers had inherent viscosity (η inh) ranging between 0.21–0.28dL/g and had excellent thermal stability with 10% weight loss at 346–508°C. [ABSTRACT FROM AUTHOR]

Abstract: Thermally stable hyperbranched polyamide-ethers (HBPAEs) containing pyrimidine moieties were synthesized using new AB2 type monomer, 6-hydroxy-2,4-bis(4′-nitrobenzamide)pyrimidine (NAL), which was prepared through amidation and its structural characterization was made by FTIR, 1H, 13C NMR spectrometry and elemental analysis. Polymerization of NAL proceeded homogeneously to yield a gel-free polymer (HBPAE 1). End group derivatization of nitro-terminated HBPAE 1 yielded HBPAE 2 and 3. FTIR confirmed the structure and complete modification of ensuing polymers. DB and inherent viscosity (η inh) of HBPAE 1 was found to be 0.41 and 0.23 dL/g, respectively. Modified HBPAE 2 and 3 were soluble in various organic solvents including NMP, DMAc and DMSO but amorphous HBPAE 1 was partially soluble in DMF. Glass transition temperature (T g) of thermally stable HBPAEs was affected by nature of end groups as well as introduction of pyrimidine rings. [Copyright &y& Elsevier]

Abstract: New type of aromatic–aliphatic polyamide/montmorillonite nanocomposites were produced using solution intercalation technique in dimethylacetamide. The modification of clay was carried out with ammonium salt of long chain alkyl amine. The nanocomposites were probed for organoclay dispersion, mechanical, thermal and water absorption measurements. Formation of delaminated and intercalated nanostructures was confirmed by X-ray diffraction and TEM studies. Improvement in tensile strength and modulus was observed for nanocomposites with optimum organoclay content (8-wt.%). Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. Differential scanning calorimetric results revealed increase in glass transition temperatures (T g ) with augmenting organoclay in the nanocomposites. Water uptake of the nanocomposites reduced than the neat polyamide rendering decreased permeability. [Copyright &y& Elsevier]

A new monomer 5-(5-(chlorocarbonyl)-1,3-dioxoisoindolin-2-yl) isophthaloyl chloride was synthesized and subsequently condensed with a variety of diamines yielding a novel family of poly(amide-imide)s (PAIs), which were exploited as potential cationic sorbents for water treatment. The synthesized monomer and all PAIs were characterized using Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopic analyses. High thermal stability and molar masses of the whole PAIs family were determined using thermogravimetric analysis (TGA) and gel permeation chromatography (GPC). Decomposition temperatures and char yields were found to be in the range 422-600 °C and 2–57% respectively. X-ray diffraction (XRD) patterns revealed the crystalline nature of PAIs family with few exceptions. PAI-2 was found to be the best contender with 99% optimum adsorption capacity for both Cd(II) and Pb(II) cations at optimal conditions. Adsorption capacities have been improved till 700 and 800 mg/g for Cd and Pb respectively for 100 ppm feed concentration, which depicted the efficiency of adsorbent. Adsorption data of all PAIs fitted well to Langmuir as compared to Freundlich, Temkin and Dubinin-Radushkevich adsorption models and exhibited favorable monolayer adsorption mechanism. The relative uptake of cations by PAIs followed the preferential trend Fe(II) > Pb(II) > Cd(II) > Cu(II) in a mixture of metal ions. [Display omitted] • Design and synthesis of a novel family of poly(amide-imide)s as chelating resins. • Efficient binding of Pb(II) & Cd(II) ions with donor sites of these copolymers. • Probing the potential of PAIs family as solid sorbents for water remediation. [ABSTRACT FROM AUTHOR]

Abstract: Semi-aromatic polyamide/organoclay nanocomposites were generated through solution blending technique. Surface modification of the montmorillonite clay was performed with p-amino benzoic acid for ample compatibilization with the polyamide matrix. The polymer chains were produced from the condensation of 4-aminophenyl sulfone with sebacoyl chloride. Interaction between the two phases was established by modifying the polymer chains with amine end groups using 1% surplus diamine near the completion of the reaction. The effect of clay dispersion and the interaction between clay and polyamide chains on the properties of nanocomposites were investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), tensile testing of thin films, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and water uptake measurements. The structural investigations confirmed the formation of delaminated nanostructures at low clay contents and disordered intercalated morphology at higher clay loadings. This morphology of the nanocomposites resulted in their enhanced mechanical and thermal properties. The tensile behavior and thermal stability significantly amplified while permeability decreased with increasing dispersibility of organoclay in the polyamide matrix. [Copyright &y& Elsevier]

Abstract: Montmorillonite clay modified with the ammonium salt of amine terminated amide oligomer was employed in the preparation of aromatic polyamide/organoclay nanocomposites. Organoclay prepared was examined for its dispersion behavior in the polyamide matrix. High-molecular-weight amide chains were synthesized from 4,4′-oxydianiline and isophthaloyl chloride in dimethylacetamide. These amide chains were selectively end-capped with carbonyl chloride end groups to interact chemically with modified montmorillonite clay. The resulting composite films containing 2–20wt.% of organoclay were characterized for TEM, XRD, thin film tensile testing; TGA, DSC and water absorption measurements. The distribution of organoclay and nanostructure of the composites were investigated by XRD and TEM analyses. Results from mechanical testing revealed that modulus and strength improved up to 6wt.% clay loading while elongation and toughness of nanocomposites increased with the addition of 2wt.% clay content in the matrix. Thermal decomposition temperatures of the nanocomposites were in the range 300–450°C. These nanocomposites exhibited increase in the glass transition temperatures relative to pristine polyamide depicting interfacial interactions between the two phases. The percentage water absorption of these hybrids was found to be much reduced upon the addition of modified layered silicate indicating decreased permeability. [Copyright &y& Elsevier]