فصلنامه مواد پیشرفته و پوشش های نوین
پیاپی 40 (بهار 1401)

The green synthesis of 2H-indazolo[2,1-b] phthalazine-triones, as a group of phthalazine derivatives, and triazolo[1,2-a]indazole-triones, as a group of urazole derivatives by employing three-component condensation of aldehydes and dimedone with a phthalhydrazide or N-phenylurazole is an actively growing area in organic synthesis. A simple, ecofriendly method based on using tungstate sulfuric acid (TSA), as a highly efficient catalyst, is proposed for the one-pot synthesis of 2H-indazolo[2,1-b]phthalazine-trione and triazolo[1,2-a]indazole-trione derivatives by the three-component condensation reaction of 4-phenylurazole or phthalhydrazide, dimedone, and various aromatic aldehydes under solvent-free conditions in excellent yields and very short reaction times. It was found that low amount of the catalysts is optimized amount to achieve desired products in short times (5-10 min) with high isolated yields (90-95%). Some superiorities of the introduced catalysts are their novelty, simple separation and their reusability up to six repeated runs without significant catalytic deactivation. principals such as green conditions, straightforward processes without any byproduct, no need for expensive, time consuming and tedious extraction or purification techniques which could make this catalyst favorable and superior catalysts for organic transformations.

Recently, hydrogel drug delivery systems based on natural polymers have received a lot of attention and in this regard, various polymers have been used individually or in combination to achieve more desirable properties. In this study, different concentrations of lidocaine hydrochloride (LidoHCl) with different percentages of gelatin / sodium carboxymethylcellulose were dissolved in water and then dispersed in paraffin medium. Hereby, microcapsules were formed and they were crosslinked with glutaraldehyde finally. Optical and electron microscope images (SEM) showed the formation of spherical microcapsules with slight surface roughness. The formation of crosslinking in the hydrogel and the lack of interaction between the drug and the polymers were investigated and confirmed by infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Evaluation of the effect of independent parameters including glutaraldehyde (GTA), drug and sodiumcarboxymethylcellulose (NaCMC) and their interaction on dependent parameters including swelling percentage, efficiency of drug loading and mean particle size by response surface method (RSM) based on central composite design (CCD) and three replications for the center point was performed. Statistical results showed that the linear effects of independent parameters have the greatest effect on dependent parameters. Based on the statistical analysis, the optimal concentration values for glutaraldehyde 5%, sodium carboxymethylcellulose 10% and drug 40% create the maximum release efficiency of the loaded drug (63.6%). Overall, the results showed that gelatin / carboxymethylcellulose hydrogel microcapsules have the potential to be used as drug carriers.

Plastisol is a suspension of small poly(vinyl chloride) particles, plasticizer, stabilizer, pigment and filler and can be used as a coating for the underbody insulator of cars. In this study, the influence of additives and fillers on the rheological and mechanical properties of plastisol were evaluated by Taguchi experimental design method, taking into account that the type and amount of PVC resin and plasticizer remained unchanged. The type of calcium carbonate and the amounts of nano-silica, solvent and liquid additive were investigated as the factors at three levels and the L9 array was used in the Taguchi design of experiment. Low and high-speed viscosities, the Bingham viscosity and the yield strength of the samples, as well as their shear resistance (shear strength) were measured. Nano-calcium carbonate increases the yield strength, Bingham viscosity and improves the flow of plastisol. The influence of liquid additive is better than that of nano-silica powder in improving the properties of plastisol. The solvent decreases the Bingham viscosity while having little effect on the yield strength of the plastisol. Nano-silica and nano-calcium carbonate have a great effect on the shear strength of plastisol and increase the shear strength.

The production of nanofiber composite as a blend of natural and synthetic polymers has received much attention in recent years.These new and advanced biomaterials are widely used in the field of biomedicine, especially drug release systems, wound dressings,tissue engineering, etc.In this research work, starch and PVA blend nanofibers were produced by electrospinning method.In fact, due to the hard processability of starch, polyvinyl alcohol was used as a processing aid.Considering the poor mechanical properties and the possibility of using these nanofibers in aqueous environments and the issue of their solubility, different cross-linking operations on starch/PVA hydrophilic nanofibers including heat,genipin,citric acid soluble in water,citric acid soluble in ethyl acetate and glutaraldehyde is investigated here.In order to ensure the achievement of the nanoscale and accurate measurement of the diameter of nanofibers,morphological images by means of a scanning electron microscope (SEM) and identification of the produced nanofibers by Fourier Transform Infrared Spectroscopy(FTIR) and X-ray Diffraction(XRD) was evaluated.Thermal stability of nanofibers before and after cross-linking was performed by thermal gravimetric analysis(TGA).Examination of morphological properties showed that fibers with uniform diameter and random arrangement were produced.With the addition of starch, a decrease in fiber diameter was observed.The results of FTIR spectroscopy and XRD studies show the proper interaction between the two polymer components and the cross-linking agent. The results obtained from solubility and TGA showed that nanofibers networked with glutaraldehyde have the highest structural stability. Finally, the results of this research indicate that Starch/PVA(GA)nanofibers will have the potential to be used in the field of biomedicine.

Graphene oxide is considered as a new type of membrane material. However, it suffers from a low steady-state filtration flux as well as unstable performance, which limits its practical applications. For this reason, the aim of this study was to combine GO with layered double hydroxides (LDH), with bilayer hydrophilic transport channels and positively charged surface in different weight ratios (i.e. 5:1, 3:1, 1:1, 1:3, and 1:5) is The optimized GO-Mg/Al/Zn-LDH was then combined with chitosan (CS) and coated on stainless steel mesh (mesh) to obtain a membrane with high stable flux that is hydrophilic and superoleophobic under water. The layer-by-layer (LBL) hybrid network morphology was fully characterized and investigated for the removal of heavy crude oil from water surfaces, with a separation efficiency higher than 99.5% (ɳ%) and a water flux of Lm-2.h-1 It showed 160222 ± 102 under the force of gravity. In addition, the exceptional mechanical/chemical stability, effective separation, high water flux, reusability and excellent superhydrophilicity, LBL hybrid mesh can be considered as a promising renewable membrane for the treatment of oily water (water containing oil droplets).

In this study, to improve the anti-corrosion properties of hydroxyapatite coating, zirconium has been used as an additive in different concentrations (0.1, 1 and 10 g/lit) in hydroxyapatite solution with optimal concentration and pH. The surface and electrochemical properties of coatings are compared with uncoated magnesium and magnesium covered by hydroxyapatite samples. AZ31 magnesium was immersed in a solution of hydroxyapatite and zirconium with different concentrations of hexafluorozirconic acid after surface treatment. The corrosion behavior of samples was studied by electrochemical impedance spectroscopy (EIS) and polarization tests in 3.5 wt% sodium chloride solution. The results of electrochemical tests showed that the best corrosion behavior is related to the samples with 1 g/lit zirconium. The corrosion resistance of this sample is 8870 Ω.cm2, which is significantly improved compared to the hydroxyapatite coating. The lowest corrosion current density (0.79 μA/cm2) among all samples is also belong to this coating. Field emission scanning electron microscopy (FE-SEM) and X-ray energy scattering spectroscopy (EDS) were used to study the morphology and evaluate the chemical composition of coatings. The results of EDS and FE-SEM confirmed the formation of hydroxyapatite crystals and amorphous zirconium layer. Contact angle test was performed to complete the surface studies of the samples. By adding 1 g/lit of zirconium to the hydroxyapatite solution, the surface became slightly more hydrophobic, which confirms the better anti-corrosion resistance.

Concrete is one of the leading materials in the field of road and construction, the use of colored concrete in urban design projects can play a significant role in improving urban beautification. The purpose of this research is to investigate the effect of four pigments, blue, green, red and yellow, on the compressive, tensile, abrasion and water absorption resistance of colored concrete with an emphasis on urban beautification. For this purpose, samples of colored concrete with 3, 5 and 7% pigments and normal concrete were tested. The test results show that The use of yellow pigment will increase the compressive strength by 10, 19 and 26 percent respectively. The use of green pigment respectively 13, 28 and 42%, blue pigment respectively 6, 11 and 24% and red pigment respectively 6, 9 and 13% will reduce the compressive strength of concrete. The use of pigment will reduce the wear resistance of concrete. This resistance reduction in red pigment is equal to 9, 16 and 19 with percentages of 3, 5 and 7 respectively, in yellow pigment it is equal to 9, 13 and 16, in green pigment it is equal to 19, 30 and 37 and in blue pigment it is equal to . It will be 13, 22 and 32 percent. Therefore, concrete with yellow pigment can be used in flooring and urban roads, but other pigments can only be used in urban walls.