Chemical Structure Stability Research Articles

Development of epoxy resin-based microfluidic devices using CO2 laser ablation for DNA amplification point-of-care (POC) applications

Microfluidic devices are a rising technology to automatize chemical and biological operations. In this context, laser ablation has significant potential for polymer-based microfluidic platforms’ fast and economical manufacturing. Nevertheless, the manufacturing of epoxy-based microfluidic chips is considered highly cost full due to the demand for cleanroom facilities that utilize expensive equipment and lengthy processes. Therefore, this study targeted investigating the feasibility of epoxy resins to be fabricated as a lab-on-chip using carbon dioxide laser ablation. The chemical structural properties and thermal stability of the plain epoxy resins were characterized by Fourier transform infrared spectral analysis (FT-IR) and thermogravimetric analysis (TGA). Moreover, a specific migration test was performed to quantify potential migrants by gas chromatography coupled to mass spectrometry (GC–MS) to prove that the cured epoxy resin would not release unreacted monomers to the biological solution test, which caused inhibition of the sensitive biological reactions. By investigating the impact of this process on microchannels’ dimensions and quality, a laser technique using CO2 laser was used in vector mode to engrave into a transparent epoxy resin chip. The resulting microchannels were characterized using 3D laser microscopy. The outcomes of this study showed considerable potential for laser ablation in machining the epoxy-based chips, whereas the microchannels machined by laser processing at an input power of 1.8 W and scanning speed of 5 mm/s have an aspect ratio of about 1.19 and a reasonable surface roughness (Ra) of ~ 15 µm. Meanwhile, the bulge height was 0.027 µm with no clogging, and HAZ was ~ 18 µm. This study validated the feasibility of quick and cost-effective CO2 laser microfabrication to develop epoxy resin-based microfluidic chips without the need for cleanroom facilities that require expensive equipment and lengthy process.

Synthesis of Rigid Polyurethane Foams Incorporating Polyols from Chemical Recycling of Post-Industrial Waste Polyurethane Foams.

The preparation and characteristics of rigid polyurethane foams (RPUFs) synthesized from polyols obtained by glycolysis of post-industrial waste RPUFs have been studied. More precisely, waste rigid foams that have been chemically recycled by glycolysis in this work are industrially produced pieces for housing and bracket applications. The glycolysis products have been purified by vacuum distillation. The physicochemical properties of the polyols, such as hydroxyl value, acid value, average molecular weight (Mn) and viscosity have been analyzed. The chemical structure and thermal stability of the polyols have been studied by means of FTIR and TGA, respectively. Partial substitution of the commercial polyol (up to 15 wt.%) by the recycled polyols increases the reactivity of the RPUFs synthesis, according to short characteristic times during the foaming process along with more exothermic temperature profiles. Foams formulated with recycled polyols have a lower bulk density (88.3–96.9 kg m−3) and smaller cell sizes compared to a conventional reference RPUF. The addition of recycled polyols (up to 10 wt.%) into the formulation causes a slight decrease in compressive properties, whereas tensile strength and modulus values increase remarkably.

Multifunctional diphenyl ether-based, cross-linked polyisocyanide for efficient iodine capture and NO2-/SO32- electrochemical probing

Compared with the extensively reported Schiff base-type polyimine (their backbones are connected by CN bond) porous organic polymers (POPs), there are rare reports regarding the exploration of polyisocyanide (PIC)-based, C1-type polyimine POPs. Herein, a kind of diphenyl ether-based, cross-linked PIC derivative (POBI) was successfully prepared. Fundamental properties of POBI as chemical structure, morphology, porosity, and thermal stability, were characterized. N, O-heteroatoms, aromatic motif and porous framework contained in the structure of POBI make it useful as a new type of iodine capture platform. Experimental results told that POBI can adsorb iodine in both vapor (under 75 °C and normal pressure) and solution (under 25 °C in cyclohexane) states. The maximum adsorption capacities in two states reached ~ 2.29 g g−1 and ~ 239 mg g−1, respectively. At the same time, the POBI-modified electrode (POBI/CS/GCE) illustrated stronger electrochemical response toward hazardous nitrite (NO2-) and sulfite (SO32-) anions relative to that of controlling electrodes (pristine glassy carbon electrode (GCE) and chitosan (CS)/GCE). The corresponding detection limits reached ~ 0.40 μmol L−1 (NO2-) and ~ 16.50 μmol L−1 (SO32-), respectively. We envisage that this work could play a positive role in further broadening the functional applications of polyisocyanide compounds.

High-Performance and Water Resistant PVA-Based Films Modified by Air Plasma Treatment

Plasma treatment is considered a straightforward, cost-effective, and environmental-friendly technique for surface modification of film materials. In this study, air plasma treatment was applied for performance improvement of pure PVA, cellulose nanocrystal (CNC)/PVA, and CNC/oxalic acid (OA)/PVA films. Compared with the original performance of pure PVA, the mechanical properties and water resistance of air plasma treated films were greatly improved. Among them, the CNC/OA/PVA film treated by three minutes of air plasma irradiation exhibits the most remarkable performance in mechanical properties (tensile strength: 132.7 MPa; Young’s modulus: 5379.9 MPa) and water resistance (degree of swelling: 47.5%; solubility: 6.0%). By means of various modern characterization methods, the wettability, surface chemical structure, surface roughness, and thermal stability of different films before and after air plasma treatment were further revealed. Based on the results obtained, the air plasma treatment only changed the surface chemical structure, surface roughness, and hydrophobicity, while keeping the inner structure of films intact.

Inhibiting mutant KRAS G12D gene expression using novel peptide nucleic acid-based antisense: A potential new drug candidate for pancreatic cancer.

KRAS mutations, which are the main cause of the pathogenesis of lethal pancreatic adenocarcinomas, impair the functioning of the GTPase subunit, thus rendering it constitutively active and signaling intracellular pathways that end with cell transformation. In the present study, the AsPC-1 cell line, which has a G12D-mutated KRAS gene sequence, was utilized as a cellular model to test peptide nucleic acid-based antisense technology. The use of peptide nucleic acids (PNAs) that are built to exhibit improved hybridization specificity and have an affinity for complementary RNA and DNA sequences, as well as a simple chemical structure and high biological stability that affords resistance to nucleases and proteases, enabled targeting of the KRAS-mutated gene to inhibit its expression at the translation level. Because PNA-based antisense molecules should be capable of binding to KRAS mRNA sequences, PNAs were utilized to target the mRNA of the mutated KRAS gene, a strategy that could lead to the development of a novel drug for pancreatic cancer. Moreover, it was demonstrated that introducing new PNA to cells inhibited the growth of cancer cells and induced apoptotic death and, notably, that it can inhibit G12D-mutated KRAS gene expression, as demonstrated by RT-PCR and western blotting. Altogether, these data strongly suggest that the use of PNA-based antisense agents is an attractive therapeutic approach to treating KRAS-driven cancers and may lead to the development of novel drugs that target the expression of other mutated genes.

Stabilization of PE with Pomegranate Extract: Contradictions and Possible Mechanisms.

Dry pomegranate peel was extracted with acetone and the extract was added to a Phillips type polyethylene. The concentration of the extract was changed from 0 to 1000 ppm in six steps and stabilization efficiency was checked by the multiple extrusion of the polymer followed by the characterization of chemical structure, processing, and residual stability. The results confirmed the excellent processing stabilization efficiency of the extract, but also the poor long-term stability of PE containing it in accordance with previously published results. The extract is amorphous and its solubility is relatively large in the polymer; thus, these factors cannot be the reason for the poor stabilization efficiency in an oxygen-rich environment. Chemical factors like the self-interaction of the polyphenol molecules, the stability of the radicals forming after hydrogen abstraction, and the lack of hydrogens with the necessary reactivity must be considered during the evaluation of the efficiency of the extract. These factors as well as the insufficient number of active hydrogens hinder the reaction of the additive molecules with oxygen-centered radicals, thus leading to inferior long-term stability. The extract can be used for the processing stabilization of polymers, but for applications requiring long-term stability, it must be combined with other natural antioxidants like flavonoids or Vitamin E.

Viscoelastic and Thermal Properties of Styrene Modified Fir Wood.

The modification of wood and its surface is one of the challenges that is being perfected with the aim of transitioning to sustainable management. This study investigated the dynamic mechanical and thermal behaviour of unmodified and styrene modified fir wood (Abies alba Mill.). Styrene monomer was chosen and impregnated into the porous structure of fir wood by reversible addition-fragmentation chain transfer (RAFT) polymerisation. Attenuated total reflection Fourier-transform infrared spectroscopy (FTIR-ATR), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA) were employed to characterise the chemical structure, viscoelastic properties, and thermal stability of unmodified and modified (surface-modified) wood. All tests have to be regarded as being preliminary due to the small number of specimens. Fourier transform infrared analysis showed evidence of the phenyl group from styrene at 700 cm−1. DMA results showed that the modified wood caused an increase in the glass transition temperature relative to the unmodified wood. In addition, modification with styrene improves thermal stability, as revealed by thermogravimetric analysis (TGA).

Iodine-doped fibrous sulfurized polyacrylonitrile with accelerated reaction kinetics

Sulfurized polyacrylonitrile (SPAN) is a promising candidate cathode material for the next-generation lithium-metal batteries due to its unique chemical structure and excellent electrochemical stability. Although SPAN is a type of conductive conjugated polymer, it suffers from the slow reaction kinetics resulting from its insufficient electronic conductivity. In this work, we propose a freestanding fibrous SPAN with an accelerated reaction kinetics by iodine doping. According to Raman, X-ray photoelectron spectroscopy and thermal analysis, sulfur and iodine atoms existing in the form of C–S/S–S and C–I bonds in the iodine-doped sulfurized polyacrylonitrile (I-SPAN), respectively. The electrochemical tests reveal that the charge transfer in I-SPAN improved significantly. A high reversible specific capacity of 1201 mAh g−1 is achieved after 400 cycles at 1000 mA g−1.

Making progress towards promising energetic cellulosic microcrystals developed from alternative lignocellulosic biomasses

ABSTRACT This study reported the valorization of various alternative lignocellulosic feedstocks including giant reed (GR), palm fronds (PF) and esparto grass (EG) for the development of promising nitrated structurally modified cellulosic biopolymers (NNCs). The extracted nanostructured cellulose precursors and their nitrated derivatives were analyzed for their physicochemical properties, chemical structure, crystallinity and thermal stability. Experimental findings confirmed the successful formation of the desired energetic NNCs polymers with increased densities (1.698–1.711 g/cm3) and high nitrogen contents (13.10–13.26%) followed the order NNC-EG>NNC-PF>NNC-GR, which are greater than those of the commonly used nitrocellulose (1.650–1.670 g/cm3 and 12.50–12.70%). Furthermore, isoconversional integral models (TAS, it-KAS and VYA/CE) were exploited based on non-isothermal DSC data to investigate their thermal decomposition kinetics. The predicted kinetic parameters displayed that the synthesized energy-rich NNCs presented close values of Arrhenius parameters within the range of 156 ≤ Eα (kJ/mol) ≤163 and 14.7 ≤ Log(A(s−1) ≤ 15.6, and decomposed following diverse reaction mechanisms. Consequently, the explored lignocellulosic biomasses could be considered as valuable alternative non-woody resources for the production of advanced high-energy dense cellulosic biopolymers for potential application in the next generation of solid propellant formulations and composite explosives.

Analysis on the Spatial Variability Mechanism of the Characteristic Water Quality Factors of Urban River Channel Reclaimed Water

Due to the limitations of the treatment process of urban sewage treatment plants and the complexity of water sources, the rich inorganic nitrogen and trace persistent organic matter in the reclaimed water cause potential human health risks through lateral leakage or bioaccumulation during the replenishment process of rivers and lakes. Exploring the distribution law of different types of reclaimed water characteristic water quality factors and their formation in reclaimed water replenishment river channels is of great significance to river and lake management. This study takes the Beijing-Tianjin-Hebei section of the North Canal as the research area and explores the spatial variation characteristics of conventional physical parameters, full index, inorganic nitrogen, and salinity hydronium antibiotics in river water quality with the help of clustering, discrimination, principal components, and variance decomposition. The results showed that, although the spatial distribution patterns of different types of water quality factors were consistent, they all showed significant mid-upstream and downstream distribution; however, there were big differences in the degree of variation and the mechanism of variation. The spatial variation of inorganic nitrogen and antibiotics was the most obvious, whereas the variation in conventional physical parameters and the full index was the weakest, and the salinity hydronium showed moderate variation. The spatial variation mechanism of conventional physical parameters was mainly reflected in microbial degradation. The full index was the result of the combined effect of microorganisms, diffusion, the synergy of the two, and a certain degree of source-sink homogeneity. Diffusion was the main mechanism affecting the spatial variation in salinity hydronium. The spatial variation mechanism of inorganic nitrogen was mainly reflected in the source-sink homogenization and microbial degradation; as a secondary mechanism of the spatial variation of inorganic nitrogen, diffusion had a synergistic mode with microbial degradation. Antibiotics, which have great differences in chemical structural stability and biodegradability, showed high spatial variability and had the highest diffusion and microbial synergy mechanism. This research provides a quantitative analysis of the spatial variability mechanism of water quality based on variance decomposition, which has practical guiding significance for the causes of the spatial variability of river pollutants and river management.

Preparation of rigid polyurethane foam from lignopolyol obtained through mild oxypropylation.

Lignin, one of the main components of lignocellulose, can be used as an alternative to chemical polyols in the production of polyurethane because of its abundant phenolic and alcohol hydroxyls. Traditionally, lignin is directly applied in the preparation of polyurethane; however, modified lignin has been proved to be superior, especially that obtained by the oxypropylation reaction. Therefore, lignopolyol obtained by mild and efficient oxypropylation was utilized in the production of rigid polyurethane foam in this study. Specifically, the effects of the content of lignopolyol on the chemical structure, morphological structure, mechanical properties and thermal stability of the lignin-based rigid polyurethane foam were investigated. It was found that the compressive strength of the rigid polyurethane foam was significantly improved with the addition of lignopolyol compared with that of the pure polyurethane foam, which was attributed to the fact that oxypropylation made lignin into highly branched and functionalized polyols by transforming all phenolic hydroxyls into aliphatic hydroxyls. Moreover, when the molal weight of lignopolyol accounted for 40% of the added polyols, the generated foam showed optimal uniformity and regularity, and the compressive strength reached 0.18 MPa, meeting the requirements of industrial application, below which, the amount of undesired reactions is bound to increase. As a consequence, the added amount of lignopolyol was increased as much as possible on the basis of guaranteeing the desired properties, which was more conducive to realizing the green degradation and economic synthesis of rigid polyurethane foam.

Effect of the cross-linker length of thiophene units on photocatalytic hydrogen production of triazine-based conjugated microporous polymers.

Conjugated microporous polymers (CMPs) have been investigated in the field of photocatalytic hydrogen production because of their extended π-conjugation, tunable chemical structure and excellent thermal stability. Herein, we construct three CMPs based on thiophenes and triazine, and prove the effect of cross-linker length on photocatalytic activity of CMPs. BTPT-CMP1 exhibits blue-shifted optical absorption compared to BTPT-CMP2 and BTPT-CMP3 with long cross-linkers, however, possesses higher photocurrent because of the large specific surface area and small interface charge transfer resistance of BTPT-CMP1. It was found that BTPT-CMP1 (5561.87 μmol g−1 h−1) with short cross-linkers exhibits better photocatalytic performance compared to BTPT-CMP2 (1840.86 μmol g−1 h−1) and BTPT-CMP3 (1600.48 μmol g−1 h−1). Also, BTPT-CMP1 possesses a higher hydrogen evolution rate than most reported 1,3,5-triazine based conjugated polymers. These results demonstrate that the cross-linker length has great influence on the photocatalytic properties of conjugated microporous polymers, which offers theoretical direction for designing high-performance CMPs.

Comparative Study on the Properties of Inorganic Silicate and Organic Phenolic Prepolymer Modified Poplar Wood by Vacuum Cycle Pressurization

To enhance mechanical properties and improve flame retardancy and smoke suppression of fast-growing poplar wood in wood applications, the wood was impregnated and modified. An organic phenolic prepolymer and inorganic sodium silicate was used as contrasting impregnation modifiers and wood samples were impregnated by a bionic “respiration” method with alternating positive and negative pressure. The weight percentage gain, density increase ratio, mechanical properties (bending and compressive strength and hardness), and water absorption rate of inorganic and organic-impregnated modified poplar wood (IIMPW and OIMPW, respectively) were compared and these properties in IIMPW were found to be higher than those of OIMPW with the exception of the water absorption rate which was lower than the OIMPW. This was attributed to the superior absorption of sodium silicate that also improved the impregnation, reinforcement, and dimensional stability in the IIMPW. The chemical structure, crystalline structure, internal morphology, flame retardancy, smoke suppression, and thermal stability of IIMPW and OIMPW were characterized by FT-IR, XRD, SEM, CONE, and TGA. FT-IR and XRD results showed that, although IIMPW cellulose crystallinity reduced the most, more chemical bonds were come into being in IIMPW, which explained the better physical and mechanical properties of IIMPW. Compared with OIMPW, IIMPW had better flame retardant and smoke suppression performance.

A novel porous hollow carboxyl-polysulfone microsphere for selective removal of cationic dyes

Herein, we obtained porous hollow carboxyl-polysulfone (PH-CPSF) microspheres through non-solvent-induced phase separation (NIPS) method and simple modification, used as highly efficient adsorbents for removing cationic dyes from sewage. The resulting PH-CPSF microspheres possess a hollow core and sponge-like shell structure, with high surface area, durable chemical inertness and structural stability. The as-synthesized PH-CPSF microspheres deliver a desirable adsorption effect after deprotonation treatment, with an adsorption capacity reaching up to 154.5 mg g−1 at 25 °C (pH = 7) of methylene blue (MB). The inter-molecular interactions between MB and the surface of the PH-CPSF, including π-π interaction, hydrogen bonding, strong charge attraction and weak charge attraction endow the adsorption ability of the PH-CPSF. The pseudo-second-order kinetic model pronounces in the adsorption behavior, and the adsorption equilibrium data is fitted to the Langmuir model. Moreover, PH-CPSF microspheres can also be used as adsorption fillers for large-scale water purification, and a removal rate of 94.0% for MB can be achieved under a flow rate of 8000 L m−3 h−1. The reusability of 95.3% removal effect for PH-CPSF microspheres after 20 consecutive cycles can be attained by a simple regeneration treatment. The adsorption efficiency of the PH-CPSF microspheres was evaluated by variety of cationic and anionic dyes, with high adsorption capacity toward cationic dyes (100%) and less than 10% toward anionic dyes. These results manifest that PH-CPSF microspheres are a potential adsorbent with long-term purification capabilities, which are expected to be used in small and large-scale sewage treatment.

Microencapsulation of Osmanthus essential oil by interfacial polymerization: Optimization, characterization, release kinetics, and storage stability of essential oil from microcapsules.

In this paper, the interface polymerization method was used to prepare Osmanthus essential oil microcapsules. The optimal preparation process of Osmanthus essential oil microcapsules was explored as follows: the dosage ratio of Osmanthus essential oil to N100 was 6:1, the reaction temperature was 70°C, and the reaction time was 2h. The encapsulation efficiency of Osmanthus essential oil microcapsules could reach 80.31%. The particle size distribution, morphology, chemical structure, and thermal stability of the obtained microcapsules were characterized by laser particle size analyzer, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The release kinetics and storage stability experiments of the microcapsules were studied. The results showed that the average volume diameter of the microcapsules was 101.2µm. The microcapsules were in the shape of full spheres, with a smooth surface, low viscosity, and high elasticity. Microencapsulation improved the thermal stability of Osmanthus essential oil and promoted the slow release of essential oil. The synthesized microcapsules showed good storage stability under refrigerated and dark conditions, which indicated that microcapsules had broad application prospects in food, medicine, and other fields. PRACTICAL APPLICATION: In this study, we prepared a polyurea membrane to encapsulate Osmanthus essential oil microcapsules by interfacial polymerization. The encapsulation conditions of the microcapsules were optimized and the structure of the microcapsules was characterized in this study. The results showed that microcapsules had a full spherical shape with a smooth surface, high elasticity, good sustained-release ability, good thermal stability, and storage stability. These properties indicated that microcapsules have good application prospects and can be used as a high-quality flavor with a long residual effect and high thermal stability for food and cosmetic scope.

Reducing sugar production from spent coffee grounds using microbubble-assisted synthesis of silica acid catalyst

The popularity of coffee as a beverage has led to a large amount of spent coffee waste worldwide, of which spent coffee ground (SCG) is one of the most heavily generated residues. Considering the environmental and social pressure to reduce pollution and increase sustainability, it is important to explore the application of SCGs in the field of renewable energy. Polysaccharides account for the most abundant components in SCGs, mainly including hemicellulose, cellulose, lignin, fat, and dietary fiber. Herein, SCG is utilized as an alternative to commercial cellulose to produce reducing sugars via hydrolysis using a sulfonated silica catalyst. Sulfonated silica catalysts are heterogeneous catalysts with advantages comprising easy separation and high recyclability. In this study, a simple and template-less method to synthesize mesoporous silica substrates by employing an in-situ microbubble generator was developed. The microbubbles generated during silica synthesis enhanced the structural properties and production yield of the silica spheres. The produced silica substrates were subjected by hydrothermal sulfonation, which resulted in a total acid density of 5.49 mmol g−1 and sulfonic acid density of 0.87 mmol g−1. The total reducing sugar yield of 31.4% was achieved by SCG hydrolysis over microbubble-assisted sulfonated silica catalysts (SSCs) at 150 ℃ for 15 h, with C6 sugars including mannose and galactose as the main products. The recyclability of SSCs was determined with a reusability test under identical coffee hydrolysis conditions. A reducing sugar yield of 96% could be maintained, which verified the high chemical structural stability of SSCs during the synthesis employing the bubble generator and hydrothermal sulfonation process. For comparison, the SSCs prepared by stirring at room temperature without a micro-bubble generator showed a relatively lower sugar yield of 24% under the same hydrolysis conditions. Therefore, this novel microbubble-assisted synthesis described herein is a promising economical, eco-friendly, and simple technique for fabricating structural silica templates as catalyst supports for biomass conversion.

Electrochemical performance of Sr1.9La0.1Fe1.5Mo0.5O6-δ symmetric electrode for solid oxide fuel cells with carbon-based fuels

La-doped Sr2-xLaxFe1.5Mo0.5O6-δ perovskite oxides are synthesized and used as a symmetric electrode to evaluate the effect of La on the crystal structure, conductivity, and catalytic activity for O2 reduction and H2 oxidation reaction. The electronic doping effect dominates the oversize effect in Sr2-xLaxFe1.5Mo0.5O6-δ oxide, resulting in unit cell volume expansion and decreased conductivity in air. In addition, the introduction of La increases the chemical structural stability of Sr2Fe1.5Mo0.5O6-δ in reducing condition due to the higher La–O bond compared with Sr–O bond, leading to high catalytic activity for the H2 oxidation reaction. At 800 °C, the Rp values of Sr1.9La0.1Fe1.5Mo0.5O6-δ symmetric cell in air and wet H2 are as low as 0.075 and 0.21 Ω cm2, respectively. Moreover, the peak power densities of 769, 561, 439, and 653 mW cm−2 at 850 °C are obtained when wet H2, CO, CH4, and C3H8 are used as fuels on Sr1.9La0.1Fe1.5Mo0.5O6-δ/LSGM/Sr1.9La0.1Fe1.5Mo0.5O6-δ cell. The symmetric cell also shows excellent stability (>100 h) in wet H2/air, implying Sr1.9La0.1Fe1.5Mo0.5O6-δ oxide is a promising symmetric electrode material.

Synthesis and characterization of polyaniline/nanodiamond hybrid nanostructures with various morphologies to enhance the corrosion protection performance of epoxy coating

In this study, nano-sized diamond particles (ND) were functionalized in two consecutive stages. First, dry thermal oxidation was employed to obtain carboxylated ND. In the next step, carboxylated ND was properly surface modified through wet chemistry to acquire aminated-ND (ND-NH2). Then, polyaniline (PANI) was synthesized in the presence of aminated-ND particles at a broad concentration from 1 wt% to 70 wt% to obtain PANI/ND hybrid nanostructures. The chemical structure, morphology, and thermal stability of nanoparticles were comprehensively characterized by different techniques such as FT-IR, UV–visible, TGA, XRD, FESEM, and TEM. It was observed that the morphology of PANI/ND nanostructures varied from nanotube at low concentration of ND to aggregated NDs covered by PANI at high concentration of NDs, namely at 70 wt%. Eventually, the hybrid PANI/ND nanoparticles were incorporated into epoxy coatings in order to improve the corrosion protection performance. The anti-corrosion properties of the coatings were examined carefully by electrochemical impedance spectroscopy (EIS). The results indicated that the morphology of PANI/ND nanohybrid structure dominated greatly the corrosion protection behavior of epoxy coating. Accordingly, it was revealed that PANI/ND5%-epoxy nanocomposite showed improved and synergistic corrosion resistance compared to neat epoxy, ND-epoxy, PANI-epoxy and even PANI/ND50%-epoxy nanocomposites due to better anodic protection as well as greater barrier performance.

Synthesis and characterization of surface-active ionic liquids for their potential application in enhanced oil recovery

In enhanced oil recovery, most widely used combinations of chemical formulations incorporate surfactants, polymers and alkalis, however, it is important to investigate alternate options which could offer improved performance and superior operational flexibility in comparison to conventional technologies. Surface active ionic liquids (SAILs) are novel functional ionic liquids with amalgamated properties of surfactant and ionic liquid, which represent an interesting alternative especially in harsh reservoir conditions for enhanced oil recovery processes. The present study illustrates a methodological laboratory assessment of synthesised SAILs to investigate their applicability for enhanced oil recovery based on their physicochemical evaluation. FT-IR, 1H NMR and TGA confirmed the chemical structure and thermal stability of the synthesised C12mimBr and C16mimBr. SAILs in aqueous solution were studied to determine their surface and interfacial behaviour under reservoir conditions. The synthesised SAILs showed lower critical micellar concentration ∼ 200 ppm (C16mimBr) and good surface-active properties and high efficiency on the interface adsorption. The interfacial tension was reduced to ultra-low values (range of 10-3 to 10-4) in wide ranges of salinity, concentration, and temperature, thus provide valuable evidence for its application as surfactants in EOR. The phase behaviour studies further suggested the formation of WINSOR-III micro-emulsion, thus making it a robust performance formulation.

A comprehensive overview of dual-layer composite membrane for air (O2/N2) separation

The separation of air (O2/N2) via a polymeric membrane has recently piqued the interest of academic researcher as well as the industrial sector. Because of its remarkable characteristics, the polymeric membrane has emerged as one of the innovative and fast growing technology. However, two major problems faced by membrane technology, which hinder its growth in the commercial sector are, 1): The trade-off between permeability and selectivity. 2): Maintaining physical and chemical structural stability in a long-term commercial scale process. Recent advancements in membrane material, structural, and process design have enabled the development of dual-layer composite (DLC) membranes. This concept combines the benefits of both thinner mixed matrix membranes (MMMs) based active layer and porous support substrate. Due to these properties, the membrane exhibits higher perm-selectivity with enhanced mechanical strength as compared to single layer polymeric membrane. This review article mainly focused on the developmental progress of DLC membrane throughout the years. In which membrane structural details, selection criteria, fabrication methodologies, application [e.g., air (O2/N2) separation] were critically reviewed. In addition, challenges arising in the DLC membrane production and future prospects for the development of these membranes were also thoroughly discussed in this literature. This creates a paradigm for future research in the commercial development of these membranes for the air (O2/N2) separation process, which can be utilized in both medical and industrial sectors. [Formula: see text]