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In this study a new melamine-terephthaldehyde resin modified graphene oxide was synthesized and used as a reinforcement of poly(vinyl chloride) (PVC). Characterization, morphology, thermal and mechanical properties of the nanocomposites were examined by means of attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray diffraction, field emission-scanning electron microscopy, thermogravimetric analysis, differential scanning calorimeter and tensile properties. The first hydrochloric acid releasing data of poly(vinyl chloride) was removed by incorporation of the modified graphene oxide as compare to the neat polymer. The temperatures at 2 wt% losses, main decomposition temperatures, maximum decomposition temperatures, also shift to higher temperature in the corresponding nanocomposites as compared to the neat PVC. The tensile strength and elongation at break of the nanocomposite films was increased as compared to the neat PVC. The interesting results in crystallinity of PVC were observed with adding 5 wt% of the modified graphene oxide. [ABSTRACT FROM AUTHOR]

In this work: ( i ) magnetic nanoparticles of Fe 3 O 4 are synthesized via precipitation method, functionalized with β -cyclodextrin hydroxyl-rich precursor, and characterized by FTIR, TEM and magnetic hysteresis loop techniques; ( ii ) epoxy nanocomposites containing bare and β -cyclodextrin-modified Fe 3 O 4 nanoparticles are prepared, and their cure behavior/kinetics has been studied by isoconversional models applied on dynamic DSC data; ( iii ) adhesion energy between cure moieties and surface of β-cyclodextrin is quantified using molecular dynamics simulation. Activation energy of epoxy resin increased from 56 to 62 kJ/mol upon introduction of β -cyclodextrin-modified Fe 3 O 4 to the epoxy, which suggests retarded crosslinking compared to the blank system, while a highly cured network was identified for the resin containing β-cyclodextrin-modified Fe 3 O 4 particles due to additional chemical reaction of hydroxyl functional groups attached to Fe 3 O 4 surface with cure moieties. Molecular dynamics simulation confirmed either quantitatively or qualitatively the strong adhesion between cure moieties and β-cyclodextrin surface. [ABSTRACT FROM AUTHOR]

To overcome water absorption and swelling by clay mineral layers, it is very important to develop stabilizing additives for water-based drilling fluids, where organic polymers are used as raw materials. Acrylamide copolymers, acting as flocculating agents, have the potential to separate minerals such as montmorillonite. In this study, three water-soluble copolymers containing acrylamide-amphoter, acrylamide-amphoter-anion, and acrylamide-amphoter-cation were synthesized and characterized using various analytical techniques, including Fourier-transform infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, and derivative thermal gravimetric techniques. These copolymers were employed as flocculants to treat water suspensions containing montmorillonite particles, and a range of analytical methods, such as sedimentation volume measurement, scanning electron microscopy analysis, X-ray diffraction analysis, and contact angle measurement, were employed to identify the relationship between inhibitive performance. The flocculation of montmorillonite plates was attributed to the electrostatic attractions between montmorillonite and the synthesized copolymers. High molecular weight copolymers offer greater thermal stability and better flocculation characteristics for water-based drilling fluids. Among the tested copolymers, the acrylamide-amphoter-anion sample, with the highest molecular weight, exhibited the best performance as a coagulant when compared to the other copolymers. [ABSTRACT FROM AUTHOR]

Hydrazide-hydrazone based polyamide (HHPA) was synthesized from an aromatic diamine containing hydrazide-hydrazone group and dodecanedioic acid via direct polycondensation. The surface modified hydroxyapatite (SMHA) was prepared using a modification process of hydroxyapatite nanoparticles (HAN) with imine functionalized polyethyleneimine (FPEI). The new pol(ylactic acid) (PLA)/HAN/HHPA nanocomposites with increased heat and combustion resistance, and improved mechanical and gas barrier properties were fabricated using solution casting method. The structure and morphology of the prepared PLA nanocomposites were evaluated using FTIR, FE-SEM, and XRD techniques. The synergistic effect of SMHA and HHPA was studied on the heat and combustion resistance, gas barrier properties, and mechanical strength of PLA. The findings exhibited that HAN was homogeneously dispersed in the PLA polymeric network, due to the excellent interfacial interactions. The TGA results of nanocomposites revealed that PLA containing 3 mass% of each SMHA and HHPA additives, named PHP6, offers more heat resistance, in both N 2 and air environment, compared to the neat PLA. According to the MCC results, the heat release rate peaks reduced from 555 W/g to 357 W/g for PLA containing 6 mass% of each SMHA and HHPA additives, named PHP12. From mechanical test, the tensile strength of PHP6 was obtained 88.27 MPa, which was 48 MPa higher than the neat PLA. Furthermore, the gas barrier studies for CO 2 and N 2 indicated that the incorporation of both HHPA and SMHA results in reduced permeability and solubility coefficients compared to the neat PLA, where PHP2 and PHP6 samples outperform other samples. • Synthesis of hydrazide-hydrazone based polyamide (HHPA) with bulky pendant group. • Preparation of PLA hydroxyapatite nanocomposites containing HHPA. • Study of PLA nanocomposite structures and morphologies. • The effect of additives on the thermal and combustion properties. • Study on mechanical and gas barrier properties of resulted PLA nanocomposites. [ABSTRACT FROM AUTHOR]

Abstract: In this work, new polyacrolein/MCM-41 nanocomposites with good phase mixing behavior were prepared through an emulsion polymerization technique. Mesoporous silica was synthesized by in situ assembly of tetraethyl orthosilicate (TEOS) and cetyl trimethyl ammonium bromide (CTAB). The structure and properties of polyacrolein containing nanosized MCM-41 particle (5 and 10 wt%), were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, Dynamic light scattering (DLS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption techniques, and thermogravimetric (TGA) analyses. The SEM images from the final powder have revealed good dispersion of the MCM-41 nanoparticles throughout polymeric matrix with no distinct voids between two phases. The results indicated that the thermal properties of the nanocomposite were enhanced by addition of MCM-41. Thermomyces lanuginosa lipase (TLL) was used as a model biocatalyst and successfully immobilized with polyacrolein and the nanocomposite via covalent bonds with the aldehyde groups. The activity between free enzyme, polyacrolein, and MCM-41 nanocomposite (10 wt%)-immobilized TLL was compared. The immobilized lipase with the nanocomposite shows better operational stability such as pH tolerance, thermal and storage stability. In addition, the immobilized lipase with the nanocomposite can be easily recovered and retained at 74% of its initial activity after 15 time reuses. [Copyright &y& Elsevier]

• A new approach was adopted to design monovalent cation permselective membranes. • Silane functionalized graphene oxide(S-f-GO) was added to the anionic layer. • Incorporating S-f-GO improved the compactness of the terminating cationic layer. • The (S-f-GO)-containing membranes exhibited the antifouling property of membranes. • Incorporating S-f-GO enhanced monovalent permselectivity (P Mg 2 + Na + ) up to 6. This study reports a novel layer-by-layer (LbL) strategy for producing a monovalent cation perm-selective membrane with an improved antifouling property. LbL architectures were fabricated by using the polyvinyl chloride (PVC) based heterogeneous cation exchange membrane as the substrate and chitosan (CS) and polyacrylic acid (PAA) as the polycation and polyanion, respectively. The coating layers on the substrate consist of 1.5 bilayers with CS as the initiating and terminating layer and PAA blended with silane functionalized graphene oxide (S-f-GO) as the middle layer. Molecular electrostatic potential (MEP) of the utilized materials proved the availability of appropriate reactive sites in their structures. FTIR spectra, EDX analysis, zeta-potential measurement, and FESEM images verified successful LbL assembly of CS and PAA blended with S-f-GO. The presence of S-f-GO in the anionic layer of the LbL architectures caused more compactness of the terminating cationic layer and increased the porosity of the anionic layer. LbL membranes containing S-f-GO possessed lower surface roughness and more hydrophilic surface and provided higher antifouling property, monovalent selectivity, and electrical conductivity than LbL architecture without additive. Results showed that utilizing 2 wt% S-f-GO in the anionic layer led to increasing permselectivity (P Mg 2 + Na + ) from 1.03 to 6. Also, the incorporation of S-f-GO was found to enhance the regeneration ability of the LbL membranes. This novel strategy for producing the MCPM can open up a new insight into designing advanced monovalent selective ion exchange membranes. [ABSTRACT FROM AUTHOR]

Transparency is a crucial factor in developing functional and decorative thin films and coatings, but incorporation of nanoparticles into organic resins for improving their properties quite often makes them opaque. In this work, photophysical properties of epoxy/layered double hydroxide (LDH) nanocomposite coatings were correlated with the dispersion state of LDH in the epoxy resin. The quality of solid epoxy network was assessed in terms of the Cure Index (CI) in relation to the transparency of the films containing 0.1, 0.5, 0.7, 1.0, and 3.0 wt% Mg–Al–LDH and Zn–Al–LDHs. At high loadings, direct transmittance (YDirect) decreased, while the light scattering in the coatings improved with respect to the neat epoxy. The highest Zn–Al–LDH loading (3.0 wt%) slightly deteriorated the transparency (YDirect = 93.3), but it was still higher than that of epoxy nanocomposite containing 0.5 wt% Mg–Al–LDH (YDirect = 89.8). A Good label was assigned to the epoxy nanocomposites containing up to 1.0 wt% Zn–Al–LDH, while epoxy/Mg–Al–LDH nanocomposites were Poor in terms of the CI labeling when Mg–Al–LDH content was more than 0.1 wt%. An increase of about 28 °C in the Tg value after the addition of 0.1 wt% Zn–Al–LDH indicated that Zn–Al–LDH can make strong the interaction between the epoxy matrix and nanoplatelets. However, decrease in the Tg of the epoxy/Mg–Al–LDH nanocomposites was a signature of the weak interactions between the Mg–Al–LDH nanoplatelets ‎and epoxy matrix due to inappropriate dispersion. In general, it was revealed for the first time that the CI enables correlating the chemical crosslinking with the photophysical properties of the epoxy/LDH nanocomposites. [ABSTRACT FROM AUTHOR]

To improve the flame retardant efficiency of PP, a new ternary polypropylene (PP) hybride containing, micro-size magnesium oxide (MgO) and nano size hydroxyapatite (HA) particles was prepared via melt blending technique. To better distribute particles in the PP matrix and enhance the effect of flame retardancy, SABO-STAB UV94 (SABO) was mixed in MgO (SABO@MgO) and used for the preparation of the PP composite and nanocomposites. X-ray diffraction (XRD) and elemental mapping results indicated that the HA nanoparticles were uniformly dispersed in the PP matrix. According to the results of thermogravimetric analysis (TGA), the maximum mass loss temperature (T max) and char residue of the PP systems were increased, as compared to the neat PP. The cone calorimeter results also indicated that the total heat release (THR) of the PP nanocomposite with 20 mass% SABO@MgO and 5 mass% HA nanoparticles was decreased from 124 kJ/m2 to 102 kJ/m2, as compared to the neat PP, passing the V-0 rating at the UL-94 test. The peak heat release rate (pHRR) of the PP nanocomposite with 20 mass% MgO and 5 mass% HA nanoparticles was also decreased from 834 kW/m2 to 545 kW/m2. Further, according to the results of the tensile test, the tensile strength of the PP nanocomposite with 20 mass% MgO and 5 mass% HA nanoparticles was increased from 44.4 MPa (for the neat PP) to 54.1 MPa. • Effect of SABO@MgO composite on the flame retardancy of polypropylene (PP) was investigated. • Preparation of SABO@MgO/hydroxyapatite PP nanocomposite with reduced MgO content. • Mechanical properties and Flame retardancy of PP system were investigated. • Flame retardancy of PP was improved in the presence of HA nanoparticles. [ABSTRACT FROM AUTHOR]

In this study, the potential of microporous 3D metal–organic framework (MOF) for curing epoxy resin has been discussed. First, MIL-101 (Cr), a chromium based MOF, was synthesized under hydrothermal condition and then characterized by using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetric (TGA) measurements. Epoxy nanocomposites containing 0.1, 0.3 and 0.5 wt% of MOF nanocrystals were subsequently prepared and their curability was studied in terms of the universal dimensionless Cure Index (CI) criterion under nonisothermal differential scanning calorimetry (DSC). Based on calculations made on the basis of the CI , epoxy nanocomposites containing 0.1, 0.3, and 0.5 wt% of MOF were labeled Good and Excellent thanks to an enhanced chemical interaction between MOF and epoxy matrix, where the heat of cure in the system was surprisingly even higher than that of the neat epoxy. It was demonstrated that introduction of MOF into epoxy significantly improved the heat release during crosslinking process of epoxy, as indicated by a 63% rise in the enthalpy of cure at MOF loading of 0.1 wt%. Addition of thermally stable MOF nanomaterials to the epoxy resin improved thermal decomposition resistance of epoxy. Up to 0.3 wt% loading, the system revealed acceptable thermal stability at elevated temperature featured by more residue remained at the end of test, while sample containing 0.5 wt% MOF resisted against decomposition at early stages of degradation due to higher thermal stability of MOF with respect to epoxy resin. Image 1 • Synthesized 3D metal–organic framework (MOF) structures and fully characterized them. • Prepared epoxy/MOF nanocomposites at different loading levels and cured nonisothermally. • Studied cure potential of nanocomposites by nonisothermal DSC varying heating rate. • Cure Index demonstrated Good and Excellent cured epoxy/MOF at high heating rates. [ABSTRACT FROM AUTHOR]

Self‐healing polyol/borax hydrogels have found great applications in various areas; especially in sensors, flexible electronics and biomedical fields. In this review, fabrication and characteristics of various types of borax‐based hydrogels are discussed. Mechanical properties and self‐healing behaviors of these hydrogels are strongly affected by the types of polyol, ratio of polyol:borax, and concentration of each component. Incorporation of highly polar nanofillers (such as cellulose nanofibers) into hydrogels and fabrication of double‐network structures have been employed as the promising strategies for improving the mechanical properties. Other additives have also been examined to generate nanocomposite hydrogels for a wide variety of uses; e. g. polyphenols for developing adhesives, conducting polymers, and hybrid structures based on carbon nanotubes and graphenes for electroconductivity, Ag and ZnO nanoparticles for antibacterial property, and quantum dots for fluorescence. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Hydroxyl-rich halloysite nanotube (HNT)/silica nanosphere (SiO 2) core/shell particles were functionalized with multi-arm hyperbranched polyethylenimine macromolecule to develop epoxy superadhesives for metal/polymer composite interfaces. A variety of techniques including FTIR, TGA, XRD, XPS, and TEM were employed to precisely monitor the surface and bulk chemistry of HNTs flecked with silica particles and subsequently with hyperbranched polymer. Amine groups of the functionalized core/shell nanoparticles were exchanged with imide ones through the reaction with pyromellitic acid dianhydride to make the system thermally stable. Incorporation of the developed reactive bushy-surface hybrid nanoparticles into epoxy resulted in a highly crosslinkable superadhesive with exceptional thermal and mechanical properties; so that addition of only 0.5 wt% of core/shell nanoparticles caused a rise of about 31 °C in glass transition temperature with respect to the blank epoxy, suggesting very high potential of particles to cure with epoxy. Cure of adhesives containing 2 wt% of bushy-surface hybrid nanoparticles via nonisothermal differential scanning calorimetry was indicative of facilitated crosslinking, as detected by a higher enthalpy of ca. 106 J/g at low heating rate of 5 °C min−1 in a narrower temperature interval of ca. 13 °C compared to blank epoxy, visualized by the Cure Index universal dimensionless criterion. From property standpoint, a rise of ca. 130% in lap shear strength was surprisingly observed for adhesives containing bushy-surface hybrid nanoparticles. Graphical abstract Unlabelled Image Highlights • Developed halloysite nanotube/nanosilica (HNT@SiO 2) core/shell nanoparticles • Decorated HNT@SiO 2 core/shell nanoparticles with imidized hyperbranched polymers • Cured bushy-surface nanoparticles with epoxy and labeled as ' Excellent Cure ' • Applied chemically engineered superadhesives in metal/polymer composite interface • Lap shear strength rose by 130% upon 2 wt% addition of nanoengineered particles [ABSTRACT FROM AUTHOR]

Curing behavior of epoxy-based nanocomposites depends on dispersion state of nanofillers and their physical and chemical interactions with the curing moieties. In this work, a systematic approach was introduced for chemical functionalization of nanoparticles with macromolecules in order to enrich crosslinking potential of epoxy/amine systems, particularly at late stages of cure where the curing is diffusion-controlled. Super-reactive hyperbranched polyethylenimine (PEI)-attached nanosilica was materialized in this work to facilitate epoxy-amine curing. Starting from coupling [3-(2,3-epoxypropoxy) propyl] trimethoxysilane (EPPTMS) with hyperbranched PEI, a super-reactive macromolecule was obtained and subsequently grafted onto the nanosilica surface. Eventually, a thermally-stable highly-curable nanocomposite was attained by replacement of amine and imine groups of the PEI with imide and amide groups through the reaction with pyromellitic acid dianhydride. Fourier-transform infrared spectrophotometry, X-ray diffractometry, X-ray photoelectron spectroscopy and transmission electron microscopy approved successful grafting of polymer chains onto the nanosilica surface. Thermogravimetric analyses approved a relatively high grafting ratio of ca. 21%. Curing potential of the developed super-reactive nanoparticle was uncovered through nonisothermal differential scanning calorimetry signifying an enthalpy rise of ca. 120 J/g by addition of 2 wt.% to epoxy at 5 °C/min heating rate. Even at low concentration of 0.5 wt.%, the glass transition temperature of epoxy increased from 128 to 156 °C, demonstrating prolonged crosslinking. [ABSTRACT FROM AUTHOR]

In this research, an ultrasonic-assisted extraction followed by 2-naphthalenthiol derivatization and dispersive liquid-liquid microextraction of acrylamide (AA) was developed as simple and sensitive sample preparation method for AA in bread and biscuit samples using high performance liquid chromatography. Influence of derivatization and microextraction parameters were evaluated and optimized. Results showed that the derivatization of AA leads to improve its hydrophobicity and chromatographic behavior. Under optimum conditions of derivatization and microextraction, the method yielded a linear calibration curve ranging from 10 to 1000 μg L −1 with a determination coefficient (R 2 ) of 0.9987. Limit of detection (LOD) and limit of quantification (LOQ) were 3.0 and 9.0 μg L −1 , respectively. Intra-day (n = 6) and inter-day (n = 3) precisions based on relative standard deviation percent (RSD%) for extraction and determination of AA at 50 and 500 μg L −1 levels were less than 9.0%. Finally, the performance of proposed method was investigated for determination of AA in some bread and biscuit samples, and satisfactory results were obtained (relative recovery ≥ 90%). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this work, graphene oxide (GO) nanoplatelets were chemically functionalized with starch biopolymer to proceed with the epoxy ring opening, which is believed to be predominantly controlled by diffusion. The product was a high-performance epoxy nanocomposite for coating applications. Successful attachment of the starch to the GO surface was approved by Fourier transform infrared spectroscopy and thermogravimetric analysis. Cure behavior of neat epoxy and its nanocomposites containing pristine and starch-modified GO was studied by differential scanning calorimetry (DSC) varying the heating rate to track and compare variations in heat of cure and maximum cure temperature of samples. Eventually, the state of brittleness of specimens was assessed; both mechanistically and microscopically. The results suggest that the huge starch molecules attached to the surface of GO could efficiently contribute to the crosslinking reactions through exfoliation of GO interlayer distance leading to a significant rise in the value of heat of cure of epoxy/amine system from 448.3 mJ/mg for neat epoxy to 515.6 mJ/mg for epoxy/GO and 468.1 mJ/mg for epoxy/GO-St at low heating rate. Epoxy nanocomposites showing acceptable curing potential and fracture resistance are appeared appropriate for coating applications. [ABSTRACT FROM AUTHOR]

In this research new magnetic and semi crystalline poly(imide-ether)/zeolite nanocomposites were successfully fabricated via solution intercalation technique. For this purpose, novel functional diamine monomer, 4-(bis (4-(4-aminophenoxy)-2,5-dimethylphenyl) methyl)-N,N-dimethylbenzenamine (5), containing flexible ether, methyl and dimethylamino groups was successfully synthesized via three step reactions. The synthesized diamine (5), was used to prepare related soluble aromatic poly(imide-ether) (PIE) as a source of polymeric matrix by reaction with benzophenone-3,3′,4,4′-tetracarboxylic dianhydride. The synthesized PIE was assessed by Fourier transform infrared and nuclear magnetic resonance (1H-NMR) techniques. The synthesized PIE revealed good solubility in dipolar aprotic solvents at room temperature. The molecular geometry and electronic properties of PIE units in the ground state by DFT and B3LYP method with 6-31G (d) as basis set were studied. Due to incorporation of N,N-dimethyl amino group as an electron donor on the benzene ring in the structure of PIE, the highest occupied molecular orbitals (HOMO) are localized mainly on N,N-dimethyl aniline. The calculated energy values of HOMO and LUMO were − 5.48 and − 3.02 eV, respectively. Also, the HOMO-LUMO gap value of the studied PIE is − 2.06 eV which show PIE units having a small energy gap and are known as soft molecule. Nanozeolites ZSM-5 which synthesized from hydrothermal treatment was magnetized via chemical co-precipitation and used for preparation of new poly(imide-ether)/zeolite nanocomposites (PIEN 3% and PIEN 5%). The nanostructure and different properties of the nanocomposites were examined using transmission electron microscope, X-ray diffraction (XRD), ultraviolet-visible, gravimetric analysis (TGA), derivative of thermogravimetric, differential scanning calorimetry and vibrating sample magnetometer. The results of XRD studies illustrated that novel synthesized PIE and their nanocomposites exhibited a semi crystallinly pattern in X-ray diffraction analysis. The crystalline morphology of samples might be because of chain packaging of PIE and good intermolecular interaction of polymer chains due to presence of N,N-dimethylamine. In examining the optical properties, it has been observed that by increasing the concentration of the nanoparticle, PIEN 3% and PIEN 5% nanocomposites show decrease in wavelength and have a blue shift of 14 and 24 nm, respectively compared to pure PIE. Also, the PIEN nanocomposites under applied magnetic field exhibited the hysteretic loops of the superparamagnetic nature. Results of TGA measurement have shown that addition of MNZ-Fe3O4@ZSM-5 in PIE matrix increased the thermal stability, compared to the neat PIE. With increasing the content of MNZ-Fe3O4@ZSM-5 to 5 wt% due to agglomeration of nanoparticles T10% decreased slightly. The glass transition temperatures (Tg) of the PIE and their nanocomposites were about 240-255 °C. Briefly, the PIE and their nanocomposites showed high thermal stability while their solubility was improved. These properties will be useful for processing and new applications of poly(imide-ether). [ABSTRACT FROM AUTHOR]

Inclusion of various polymeric chains with different lengths and functionalities (such as hydrophobic, ionic, acidic, basic, etc) into polysaccharide backbones leads to new polymeric materials with interesting properties that may self-assembled into different aggregations and have the potential to for use in a variety of applications. This review highlights the application of various ATRP techniques (such as “grafting-from” and “grafting-to”) to modify non-cellulosic polysaccharides under homogenous condition. Chemical modification of chitosan, pullulan, dextran, agarose, hyaluronic acid (hyaluronan), starch, glycogen, heparin, chitin, guar gum, locust bean gum, and dextrin using ATRP are described. Pre-functionalization or protection of some functional groups in the polysaccharide backbone required in some cases to prepare a precursor with higher solubility in organic solvents is illustrated. For each polymerization, the strategy for synthesis of the copolymer and the condition of the polymerization is described in detail along with the properties of the prepared copolymers. Furthermore, examples that produced materials with the potential for use in a specific application are reviewed in summary. [ABSTRACT FROM AUTHOR]

Layered double hydroxide (LDH) has a particular place in clay family because of its flame retardant action. The nanoplatelet-like structure of LDH makes possible development of polymer composites with cationic or anionic nature structures in which macromolecules are positioned in between nanoplatelet galleries. In this work, neat epoxy and its transparent nanocomposite coatings with sodium dodecylbenzene sulfonate (SDBS)-modified LDHs; Mg-Al and Zn-Al LDHs, were prepared and their cure kinetics and viscoelastic behavior were tracked through nonisothermal calorimetric and dynamic mechanical analyses. The higher progression of crosslinking in the epoxy network was observed for epoxy/Zn-Al LDH nanocomposites, while activation energy of cure reaction took a higher value for Mg-Al LDH-incorporated systems. Moreover, epoxy/Mg-Al LDH system revealed higher value of storage modulus and glass transition temperature thanks to larger galleries of Mg-Al nanoplatelets. Network formation in the presence of SDBS-modified Zn-Al LDH nanoplatelets was facilitated due to the action of Zn metal as an adduct with a lone-pair of oxygen atom of epoxy leading to an enhanced epoxy ring-opening. Viscoelastic behavior of transparent coatings containing Zn-Al LDH and Mg-Al LDH was studied through temperature-sweep test at various frequencies to compare the results of calorimetric and thermo-mechanical analyses. [ABSTRACT FROM AUTHOR]

Fe 3 O 4 magnetic nanoparticles (MNPs) were synthesized and modified with chitosan as a natural surface modifier to prevent their aggregation and make them potent to contribute to ring opening of epoxy. Functionalized Fe 3 O 4 (Chitosan@Fe 3 O 4 ) was characterized by Fourier transform infrared, thermogravimetric analysis, transmission electron microscope and magnetic hysteresis loops measurements. The cure behavior and kinetics of epoxy nanocomposites filled with bare and chitosan-modified Fe 3 O 4 were analyzed using isothermal and nonisothermal differential scanning calorimetry (DSC). The kinetic models applied to DSC experimental data suggested positive effect of Chitosan@Fe 3 O 4 MNPs on cure reaction between epoxy and polyamidoamine hardener. Experimental and modeling outcomes from epoxy/Chitosan@Fe 3 O 4 nanocomposites were supported by theoretical quantum chemical calculations and molecular dynamics simulations. Computational studies demonstrated that curing of epoxy resin with aminoamide hardener has been governed by the interaction between epoxy and Chitosan@Fe 3 O 4 . [ABSTRACT FROM AUTHOR]

A novel chemically modified electrode is constructed based on a multiwalled carbon nanotubes, nickel(II) hydroxide nanoparticles and MCM-41 molecular sieve composite modified glassy carbon electrode. It is demonstrated that the sensor can be used for the simultaneous determination of dopamine (DA), acetaminophen (ACT) and indomethacin (INDO). The measurements were carried out by the application of differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CA). Under the optimum conditions the modified electrode provides a linear response versus DA concentrations in the range of 1.5–45 μM and 70–350 μM, ACT concentrations in the range of 0.2–20 μM and 20–220 μM and INDO concentrations in the range of 0.8–40 μM and 60–160 μM, respectively using the differential pulse voltammetry method. The modified electrode was used for determination of DA, ACT and INDO in real samples with satisfactory results. [ABSTRACT FROM AUTHOR]

In this research, an efficient sorbent based on poly(β-cyclodextrin-ester)-functionalized silica-coated magnetic nanoparticles (MNPs-CDP) was prepared and used for magnetic solid-phase extraction of the malachite green (MG) and crystal violet (CV) from water samples prior to their determination by high-performance liquid chromatography-ultra violet detection (HPLC-UV). The synthesized nanoparticles were characterized by the field emission-scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FT-IR). Of course, the factors, which could influence the extraction efficiency like pH, sorbent amount, salt content, extraction time, desorption time, eluent type, and volume and sample volume, were optimized by response surface methodology. Then, for both of MG and CV, good linearity (0.1-200 μg L -1 , r 2  ≥ 0.99) was achieved under the optimized conditions. The limits of detection (LODs) and the limits of quantification (LOQs), for both of MG and CV, were 0.03 μg L -1 and 0.1 μg L -1 , respectively. Precision of the method expressed as the relative standard deviations (RSDs) at concentration level of 100 μg L -1 was 5.6 and 4.2 for MG and CV, respectively. Ultimately, usability of proposed method was investigated by analysis of CV and MG in tap water, fish pond water, and the lake water, and the satisfactory recoveries were obtained in the range of 92-100.5%.