Manawwer Alam

Luminescent mesoporous LaVO4:Eu3+ core-shell nanoparticles: synthesis, characterization, biocompatibility and their cytotoxicity

A general and facile method was used for preparation of water-soluble silica coated LaVO4:Eu3+ core-shell nanoparticles. In the present study, we have discussed and compared the cytotoxicity characteristics of the synthesized LaVO4:Eu3+ and silica coated LaVO4:Eu3+ core-shell nanoparticles. X-ray diffraction (XRD), field-emission transmission electron microscopy (FE-TEM), energy dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FTIR), UV/Vis absorption spectroscopy and photoluminescence spectroscopic techniques were employed to characterize the structure and morphology of the prepared products. To obtain high aqueous solubility, luminescent LaVO4:Eu3+ nanoparticles were encapsulated with silica groups, giving the nanoparticles a negatively charged surface at physiological pH. The results of XRD confirm the formation of a well-crystallized LaVO4:Eu3+ phase with a tetragonal zircon structure. Optical absorption spectra show that the optical properties of silica-coated LaVO4:Eu3+ core-shell nanoparticles are related to their sizes and shapes. Further, in order to assess cytotoxicity, we investigated whether the LaVO4:Eu3+ nanoparticles could alter biological samples once they enter human H522 and peripheral blood mono nuclear cells (PBMCs). An MTT assay was performed to measure the mitochondrial activity that reflects the number of viable cells. Silica coated LaVO4:Eu3+ core-shell nanoparticles exhibited no significant effect on the viability of both types of cells up to 24 h after exposure. Strikingly, no dose effects were detected, even at highest concentrations.

Effect of surface coating on optical properties of Eu3+-doped CaMoO4 nanoparticles

A simple polyol method has been used for the synthesis of CaMoO4:Eu (core), CaMoO4:Eu@CaMoO4 (core/shell) and their silica coated CaMoO4:Eu@CaMoO4 (core/shell/shell) nanoparticles. X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), Fourier transform Raman (FT-Raman), Fourier transform infrared (FT-IR), UV/Vis absorption and photoluminescence (PL) spectroscopies techniques has been employed for their characterization. XRD patterns and FT-Raman spectra showed that these nanoparticles have a scheelite-type tetragonal structure without the presence of deleterious phases. These nanoparticles were easily dispersed in water, producing a transparent colloidal solution. The optical energy band-gap decreases after core/shell formation due to increase the crystalline size. The photoluminescence (PL) spectra of the as-synthesized core, core/shell and core/shell/shell nanoparticles measured with an excitation source wavelength of 325nm showed that the emission intensity was increases after shell formation around the surface of core nanoparticles.

Ambient Cured Tartaric Acid Modified Oil Fatty Amide Anticorrosive Coatings

A novel tartaric acid modified fatty amide diol (TAFA) was synthesized through the condensation polymerization of N,N‐bis(2‐hydroxy ethyl) linseed oil fatty amide and tartaric acid (TA).The structural elucidation of the TAFA resin was carried out by FT‐IR,1H‐NMR, and 13C‐NMR spectroscopic techniques. The physico‐mechanical and physico‐chemical characterization of the resin were done by standard methods. TAFA, when further reacted with butylated melamine formaldehyde (BMF) in different phr (part per hundred part of resin) (TAFA‐BMF) was found to cure at room temperature. The TAFA‐BMF cured system was subjected to spectroscopic analysis to ascertain the structure and curing scheme of the same. The thermal studies of these resins were carried out by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The physico‐mechanical properties and anticorrosive performance of TAFA‐BMF coatings were evaluated by standard methods. The effect of TA and BMF on thermal stability, physico‐mechanical and anticorrosive properties of resins was also investigated.

Miscibility Studies of Polyesteramides of Linseed Oil and Dehydrated Castor Oil with Poly(vinyl alcohol)

Blends of two polymers have been widely investigated to enhance or modify some of their physical or mechanical characteristics for specific applications. The investigation of miscibility of a pair of polymers is a necessary step in the investigation of the properties of the blends. Poly(vinyl alcohol)(PVA) is a commercial polymer that yields tough films of high tensile strength. They are, however, water soluble, restricting their applications. Vegetable oil constitutes a major resource for several polymeric products, such As alkyds, polyurethanes, polyepoxies, and polyesteramides. Polyesteramides, synthesized from different seed oils, have been used as an anticorrosive material but they fail to form free standing films. They can, therefore, be used for blending with PVA to lower its water sensitivity as well as to obtain free-standing films of a sustainable resource based polymer. In this study, linseed oil polyesteramide (LOPEA) and dehydrated castor oil polyesteramide (DCPEA), the source oils having different unsaturation in their fatty acids chains, were blended with PVA through mixing in solution in the weight ratios LOPEA/DCPEA:PVA: 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80. In the first phase the miscibility of the two components was investigated in solution by viscosity and ultrasonic measurements and in the solid form through differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Moisture absorption by the films of different compositions of the blends was studied. The viscosity and ultrasonic studies show that both DCPEA and LOPEA were immiscible with PVA in solution. In solid phase the DCPEA and PVA were found to be partially miscible whereas LOPEA and PVA were found to be completely immiscible. Films of the blend DCPEA:PVA:80:20 were found to be the toughest. Blends of all compositions showed lower absorption of moisture than pure PVA. In view of the toughness of its films, low moisture uptake and high content of sustainable resource based polymer, DCPEA:PVA, 80:20 blend holds potential for commercial application.

MWCNTs-Reinforced Epoxidized Linseed Oil Plasticized Polylactic Acid Nanocomposite and Its Electroactive Shape Memory Behaviour

A novel electroactive shape memory polymer nanocomposite of epoxidized linseed oil plasticized polylactic acid and multi-walled carbon nanotubes (MWCNTs) was prepared by a combination of solution blending, solvent cast technique, and hydraulic hot press moulding. In this study, polylactic acid (PLA) was first plasticized by epoxidized linseed oil (ELO) in order to overcome the major limitations of PLA, such as high brittleness, low toughness, and low tensile elongation. Then, MWCNTs were incorporated into the ELO plasticized PLA matrix at three different loadings (2, 3 and 5 wt. %), with the aim of making the resulting nanocomposites electrically conductive. The addition of ELO decreased glass transition temperature, and increased the elongation and thermal degradability of PLA, as shown in the results of differential scanning calorimetry (DSC), tensile test, and thermo gravimetric analysis (TGA). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to observe surface morphology, topography, and the dispersion of MWCNTs in the nanocomposite. Finally, the electroactive-shape memory effect (electroactive-SME) in the resulting nanocomposite was investigated by a fold-deploy “U”-shape bending test. As per the results, the addition of both ELO and MWCNTs to PLA matrix seemed to enhance its overall properties with a great deal of potential in improved shape memory. The 3 wt. % MWCNTs-reinforced nanocomposite system, which showed 95% shape recovery within 45 s at 40 DC voltage, is expected to be used as a preferential polymeric nanocomposite material in various actuators, sensors and deployable devices.

Compatibility Studies on Dehydrated Castor Oil Epoxy Blend with Poly(Methacrylic Acid)

Blending is a useful technique to improve upon the physico‐mechanical properties of the polymers. Synergies of the properties of the two polymers occur best when they are miscible or compatible with each other. Vegetable oil epoxy can be used for blending with polymers to improve upon their physical and mechanical properties. Poly(methacrylic acid) (PMAA) is a hard, brittle and water sensitive material. Dehydrated castor oil epoxy (DCOE), a product from a sustainable resource, has been chosen to improve upon the physical and mechanical properties of PMAA through solution blending. Blends of DCOE/PMAA were prepared in the weight ratios 80/20, 60/40 and 20/80 through a solution method by mixing in dimethyl sulphoxide. In the first instance, the miscibility of the two components was investigated using the techniques of viscosity and ultrasonic measurements. The study revealed that the two components showed semicompatibility/semimiscibility in solution. The compatibility in the solid phase was examined by differential scanning calorimetry and scanning electron microscopy which revealed that DCOE–PMAA pair were incompatible in solid phase.

Optical and electrical studies of polyaniline/ZnO nanocomposite

Polyaniline (Pani)/ZnO nanocomposite with diameter 40-50nm was successfully fabricated by coprecipitation method of ZnO via in situ polymerization of Pani. X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), fourier transformation infrared (FT-IR), UV-Vis absorption spectra, thermogravimetric analysis (TGA), and electrical properties were studied. HRTEM studies showed that the prepared ZnO nanoparticles were uniformly dispersed and highly stabilized throughout the polymer chain and formed uniform metal oxide-conducting polymer nanocomposite material. UV-Vis spectra of Pani/ZnO nanocomposite were studied to investigate the optical behavior after doping the ZnO nanoparticle into the polymer matrix. The inclusion of ZnO nanoparticle gives rise to the red shift of π-π* transition of Pani. The nanocomposite was found to be thermally stable upto 130°C and showed conductivity value of 3.0 × 10-2 Scm-1.

Studies on Melamine Modified Polyesteramide as Anticorrosive Coatings from Linseed Oil: A Sustainable Resource

Melamine modified polyester amide (MPEA) was synthesized by the reaction of linseed oil fatty amide. The resin was further cured at room temperature by polystyrene co‐maleic anhydride (SMA) in different phr (30–80) to obtain MPEA coatings. The probable structure of MPEA was confirmed by FT‐IR, 1H‐NMR and 13C‐NMR spectroscopic techniques. The physico‐chemical characterization of these resins viz. iodine value, saponification value, refractive index, inherent viscosity were carried out by standard methods. MPEA (40 wt%) solution in ethylene glycol monomethyl ether (EGME) was applied on a mild steel strip of standard sizes to study their physico‐mechanical and chemical resistance properties. It was found that coatings of MPEA with 60 parts per hundred of the resin (phr) of SMA showed the best performance in physico‐mechanical and alkali resistance properties. Thermal stability and curing behavior were studied by Thermo Gravimetric Analyses (TGA) and Differential Scanning Calorimetry (DSC), respectively.

Linseed oil polyol/ZnO bionanocomposite towards mechanically robust, thermally stable, hydrophobic coatings: a novel synergistic approach utilising a sustainable resource

Linseed oil polyol/ZnO bionanocomposite was prepared to obtain mechanically robust, thermally stable, hydrophobic coatings via a novel synergistic approach utilising a vegetable oil polyol for the first time. The synthesis process obviates the use of reducing agents, surfactants, reaction media, stabilizing agents, solvents, and other chemicals. Linseed polyol serves the purpose of obtaining ZnO nanoparticles. The linseed polyol backbone hosts hydroxyl and carboxylic groups that participate in the generation of ZnO nanoparticles in the polyol matrix (ester elimination, addition–elimination reaction). The progress of the reaction was monitored by recording FTIR spectra at regular intervals of time. The coatings obtained were scratch-resistant, impact-resistant, well-adherent, flexibility-retentive and hydrophobic, showing good chemical resistance under acidic, alkaline, and salt environments. Thermogravimetric analysis revealed that these coatings could be safely used up to 250 °C. The work described is consistent with the principles of “Green Chemistry” (Principles 1, 2, 3, 4, 5, 6, 7, 8, and 12), such as utilising a renewable feedstock, resorting to a solventless approach, and employing safer chemistry. The results showed that these coatings may be well employed as promising candidates towards environmentally friendly corrosion protective coatings.

Electroactive Shape Memory Property of a Cu-decorated CNT Dispersed PLA/ESO Nanocomposite

Shape memory polymer (SMP) nanocomposites with a fast electro-actuation speed were prepared by dispersing Cu-decorated carbon nanotubes (CNTs) (Cu-CNTs, 1 wt %, 2 wt %, and 3 wt %) in a polylactic acid (PLA)/epoxidized soybean oil (ESO) blend matrix. The shape memory effect (SME) induced by an electrical current was investigated by a fold-deploy “U”-shape bending test. In addition, the Cu-CNT dispersed PLA/ESO nanocomposite was characterized by atomic force microscopy (AFM), dynamic mechanical analysis (DMA) and tensile and electrical measurements. The results demonstrated that the SME was dependent on the Cu-CNT content in the nanocomposites. When comparing the SMEs of the nanocomposite specimens with different Cu-CNT contents, the 2 wt % Cu-CNT dispersed system exhibited a shape recovery as high as 98% within 35 s due to its higher electrical conductivity that results from uniform Cu-CNT dispersion. However, the nanocomposites that contained 1 wt % and 3 wt % Cu-CNTs required 75 s and 63 s, respectively, to reach a maximum recovery level. In addition, the specimens exhibited better mechanical properties after the addition of Cu-CNTs.