Research Progress on the Collaborative Drag Reduction Effect of Polymers and Surfactants

Analysis of the Drag Reduction Performance and Rheological Properties of Drag-Reducing Additives

In the practical application of hydraulic rotating machinery, it is essential to thoroughly explore drag reduction and rheological characteristics of drag-reducing additives to optimize machinery efficiency and reduce equipment consumption. This paper combines simulation and experimental approaches to investigate the drag-reduction performance and rheological properties of drag-reducing additives. Numerical simulations are initially conducted to investigate the shear-thinning properties of drag-reducing fluid and explore variations in drag-reduction rate. Turbulent phenomena characteristics are described by analyzing turbulent statistical quantities. Subsequently, the rheological behaviors of polyethylene oxide (PEO), cetyltrimethyl ammonium chloride (CTAC), and their mixed solutions under different conditions are scrutinized using a rotational rheometer. The findings indicate that the drag reduction effect amplifies as the rheological index n and characteristic time λ decrease. The numerical simulations show a maximum drag reduction rate of 20.18%. In rheological experiments, a three-stage viscosity variation is observed in single drag-reducing additives: shear thickening, shear thinning, and eventual stabilization. Composite drag-reducing additives significantly reduce the apparent viscosity at low shear rates, thereby strengthening the shear resistance of the system.

Current strategies on bioremediation of personal care products and detergents: Sustainability and life cycle assessment

The increased use of personal care products and detergents in modern society has raised concerns about their potential adverse effects on the environment. These products contain various chemical compounds that can persist in water bodies, leading to water pollution and ecological disturbances. Bioremediation has emerged as a promising approach to address these challenges, utilizing the natural capabilities of microorganisms to degrade or remove these contaminants. This review examines the current strategies employed in the bioremediation of personal care products and detergents, with a specific focus on their sustainability and environmental impact. This bioremediation is essential for environmental rejuvenation, as it uses living organisms to detergents and other daily used products. Its distinctiveness stems from sustainable, nature-centric ways that provide eco-friendly solutions for pollution eradication and nurturing a healthy planet, all while avoiding copying. Explores the use of microbial consortia, enzyme-based treatments, and novel biotechnological approaches in the context of environmental remediation. Additionally, the ecological implications and long-term sustainability of these strategies are assessed. Understanding the strengths and limitations of these bioremediation techniques is essential for developing effective and environmentally friendly solutions to mitigate the impact of personal care products and detergents on ecosystems.

A bio-inspired two-stage bionic drag reduction method

Reducing the surface resistance of underwater vehicles plays an important role in improving cruising speed and cruising mileage. The epidermis of loaches is not only covered with a layer of scale structure but also secretes mucus tissue with a lubricating effect, which makes loaches swim rapidly in muddy water. Study the morphology and structure of the skin of loach and establish a two-stage biomimetic drag reduction model. Adjust the different structural parameters of the model and select the parameters with the best drag reduction rate for the modeling design. The numerical simulation results show that the optimal drag reduction rate of the two-stage drag reduction structure is greater than 21%. In the flow channel test experiment, the drag reduction rate is slightly lower than the simulation results. Numerical simulation and experimental data show that the underwater drag reduction function can be realized by simulating the microstructure of loach skin. Finally, analyze the velocity gradient, vortices, etc., and search for the drag reduction mechanism. The simulation design of the microstructure of the loach skin can increase the thickness of the boundary layer, promote the vortex structure near the wall surface, change the flow mode of the solid-liquid interface, and reduce the wall resistance. At the same time, the drag reduction model provides key technical support for the practical application of reducing surface resistance, such as in underwater vehicles.

Novel polysaccharides-bile acid-cyclodextrin gel systems and effects on cellular viability and bioenergetic parameters

Aim: The novel hydrogel systems made from sodium alginate, pectin, beta-cyclodextrin and deoxycholic acid (DCA) were proposed as potential drug-delivery matrices. Materials & methods: To ensure biocompatibility, rheological parameters were examined and hydrogels' effects on bioenergetic parameters and cellular viability on murine hepatic, and muscle and pancreatic beta cells. Results & conclusion: All hydrogels show non-Newtonian, shear thinning behavior. Cells displayed various oxygen-dependent viability patterns, with the bile acid overall adversely affecting their biological activities. All cells performed best under normoxia, with pancreatic beta cells displaying the most profound oxygen-dependent viability behavior. The cells tolerated the addition of a moderate concentration of beta-cyclodextrin to the polymer matrix.

Hybrid Polymer-Surfactant Wormlike Micelles for Concurrent Use for Oil Recovery and Drag Reduction

We report on the effect of a hydrocarbon (n-dodecane) on the rheological properties and shapes of the hybrid wormlike micelles (WLMs) of a surfactant potassium oleate with an embedded polymer poly(4-vinylpyridine). With and without hydrocarbon solutions, the hybrid micelles exhibit the same values of viscosity at shear rates typical for hydraulic fracturing (HF) tests, as solutions of polymer-free WLMs. Therefore, similar to WLMs of surfactants, they could be applied as thickeners in HF fluids without breakers. At the same time, in the presence of n-dodecane, the hybrid micelles have much higher drag-reducing efficiency compared to microemulsions formed in polymer-free systems since they form "beads-on-string" structures according to results obtained using cryo-transmission electron microscopy (cryo-TEM), dynamic-light scattering (DLS), and small-angle X-ray scattering (SAXS). Consequently, they could also act as drag-reducing agents in the pipeline transport of recovered oil. Such a unique multi-functional additive to a fracturing fluid, which permits its concurrent use in oil production and oil transportation, has not been proposed before.

Interfacial Adsorption Controls Particle Formation in Antibody Formulations Subjected to Extensional Flows and Hydrodynamic Shear

During their manufacturing and delivery to patients, therapeutic proteins are commonly exposed to various interfaces and to hydrodynamic shear forces. Although adsorption of proteins to solid-liquid interfaces is known to foster formation of protein aggregates and particles, the impact of shear remains controversial, in part because of experimental challenges in separating the effects of shear from those caused by simultaneous exposure to interfaces. Extensional flows (occurring when solutions flow through sudden contractions) exert localized elongational forces that have been suspected to be damaging to proteins. In this work, we measured aggregation and particle formation in formulations of polyclonal and monoclonal antibodies subjected to extensional flow, high shear (105 s-1) and exposure to stainless-steel/water interfaces. Modification of the surface charge at the stainless steel/water interface changed protein adsorption characteristics without altering shear profiles, enabling shear and interfacial interactions to be separated. Even under conditions where antibodies were subjected to high hydrodynamic shear and extensional flow, production of subvisible particles could be inhibited by modifying the stainless-steel surface charge to minimize antibody adsorption. Digital images of particles recorded by flow imaging microscopy (FIM) and analyzed with machine learning algorithms were consistent with a particle formation mechanism by which antibodies adsorb and aggregate at the stainless-steel/water interface and subsequently form particles when shear displaces the interfacial aggregates, transporting them into the bulk solution. Topographical differences measured using atomic force microscopy (AFM) supported the proposed mechanism by showing reduced levels of protein adsorption on surface-charge-modified stainless-steel.

Synthesis and drag reduction properties of a hydrophobically associative polymer containing ultra-long side chains

Different from common hydrophobic associative polymers, a new hydrophobic associative polyacrylamide (HAPAM) with ultra-long side chains was synthesized and aimed to be used as drag reducer in this work. Firstly, a water-soluble hydrophobic monomer (named AT114) was obtained by alcoholysis reaction with acryloyl chloride and triton 114, then the drag reducer was obtained by radical copolymerization of AM, AMPS and AT114. The structures of AT114 and drag reducer were characterized by IR and NMR. Slick water was obtained by dissolving a small amount drag reducer in water. Although the viscosity of slick water varied greatly in fresh water and brine, the drag reduction rate always remained at a high level when flowing in pipelines. When the concentration of the drag reducer was 0.03% in fresh water, drag reduction rate can be up to 76.7%, while in high concentration brine, still as high as 76.2%. It shows that salt has no obvious negative impact on the drag reduction rate. That is also to say, in the case of low viscosity, the viscosity change has no obvious impact on drag reduction rate. From the Cryo-TEM observation, it can be concluded that the drag reducer forms sparse network structures in water, which is the direct reason for drag reducing effect. This finding provides knowledge regarding the development of new drag reducers.

Drag Reduction Technology of Water Flow on Microstructured Surfaces: A Novel Perspective from Vortex Distributions and Densities

Revealing the turbulent drag reduction mechanism of water flow on microstructured surfaces is beneficial to controlling and using this technology to reduce turbulence losses and save energy during water transportation. Two microstructured samples, including a superhydrophobic and a riblet surface, were fabricated near which the water flow velocity, and the Reynolds shear stress and vortex distribution were investigated using a particle image velocimetry. The dimensionless velocity was introduced to simplify the Ω vortex method. The definition of vortex density in water flow was proposed to quantify the distribution of different strength vortices. Results showed that the velocity of the superhydrophobic surface (SHS) was higher compared with the riblet surface (RS), while the Reynolds shear stress was small. The vortices on microstructured surfaces were weakened within 0.2 times that of water depth when identified by the improved Ω_M method. Meanwhile, the vortex density of weak vortices on microstructured surfaces increased, while the vortex density of strong vortices decreased, proving that the reduction mechanism of turbulence resistance on microstructured surfaces was to suppress the development of vortices. When the Reynolds number ranged from 85,900 to 137,440, the drag reduction impact of the superhydrophobic surface was the best, and the drag reduction rate was 9.48%. The reduction mechanism of turbulence resistance on microstructured surfaces was revealed from a novel perspective of vortex distributions and densities. Research on the structure of water flow near the microstructured surface can promote the drag reduction application in the water field.

Salt-Induced Transformations of Hybrid Micelles Formed by Anionic Surfactant and Poly(4-vinylpyridine)

Salt-induced structural transformation of charged hybrid surfactant/polymer micelles formed by potassium oleate and poly(4-vinylpyridine) was investigated by cryo-TEM, SANS with contrast variation, DLS, and 2D NOESY. Cryo-TEM data show, that at small salt concentration beads-on-string aggregates on polymer chains are formed. KCl induces the transformation of those aggregates into rods, which is due to the screening of the electrostatic repulsion between similarly charged beads by added salt. In a certain range of salt concentration, the beads-on-string aggregates coexist with the rodlike ones. In the presence of polymer, the sphere-to-rod transition occurs at higher salt concentration than in pure surfactant system indicating that hydrophobic polymer favors the spherical packing of potassium oleate molecules. The size of micelles was estimated by DLS. The rods that are formed in the hybrid system are much shorter than those in polymer-free surfactant solution suggesting the stabilization of the semi-spherical endcaps of the rods by embedded polymer. 2D NOESY data evidence that in the spherical aggregates the polymer penetrates deep into the core, whereas in tighter packed rodlike aggregates it is located mainly at core/corona interface. According to SANS with contrast variation, inside the rodlike aggregates the polymer adopts more compact coil conformation than in the beads-on-string aggregates. Such adaptive self-assembled polymer-surfactant nanoparticles with water-insoluble polymer are very promising for various applications including drag reduction at transportation of fluids.

Investigating the effect of insoluble additives type on the drag reduction performance in a crude oil turbulent flow system

In the present work, the effect of three insoluble additives densities on reducing the drag of crude oil was investigated. The objective of the present work is to evaluate the effect of the insoluble additive’s densities on their drag reduction efficiency in hydrocarbon flow medium. Three powders with different densities are chosen, namely carbon powder, glass powder, and copper powder, with a density of 1710 kg/m3, 2550 kg/m3, and 8950 kg/m3, respectively. The turbulence flow environment was created in a custom-made rotating disc apparatus with a maximum rotation speed of 300 rpm. To evaluate the effect of the powder density, the particle's size was chosen to be 100 µm. All the solutions were tested at the exact operating conditions with a rotation speed ranging between 200 to 2200 rpm. The experimental results showed a clear effect of the powder density on the drag reduction performance. The glass powders showed the highest drag reduction effect, while the copper and carbon powders were lower. The effect of the degree of turbulence on the drag reduction performance of the powders was clear, where the interaction between the powders and the turbulence structures (eddies) governed the turbulence-suppression efficiency of the additives.

Noise spectrum characteristics of marine pump units induced by different excitation sources

To study the noise spectrum characteristics of marine pump units induced by different excitation sources, a computational aeroacoustic (CAA) model of the internal and external field noise of a marine pump was established. The coupled acoustic-vibration method was used to obtain the spectrum characteristics of internal and external field noise. The accuracy and feasibility of the simulation method for noise prediction were confirmed through a noise test. Due to the different mediums in the internal and external fields of the marine pump, an external field acoustic model was established based on the automatically matched layer (AML) technology. The spectral characteristics of different excitation sources and the spatial distribution of the radiated sound field were analyzed, and the contribution of different sound source excitations to the internal and external sound field was revealed. The results show that the main frequency of the internal field noise generated by different excitations is at the blade passing frequency, and the internal field noise induced by the dipole acoustic excitations dominates at 180.6 dB. For the external field noise, the main frequency is still located at the blade passing frequency. The radiation noise induced by the fluid excitation (139.2 dB) is higher than that induced by the dipole excitations (surface dipole, 136.3 dB; rotating dipole, 137.3 dB).

Influence of Bionic Circular Groove Blade Surface on Wear Performance

In order to improve the anti-wear performance of a double-vane self-priming centrifugal pump during two-phase flow transfer, the construction of a streamline groove structure at the outlet end of the suction side of the vane, based on the bionic principle, is proposed. Different pump characteristics are analysed to investigate the effect of different bionic groove spacing on the resistance to particle wear and the mechanism of improvement of the bionic grooves. The results show that the effect of the bionic blades on the hydraulic characteristics of the pump is within the allowable error (±1.4%). The circular groove structure with different spacing produces a difference in the pressure distribution on the blade. At the same particle concentration, with the increase in the groove spacing distance, the average wear of the blades first decreases and then increases; the average wear rate at the spacing of 7 mm is the smallest. At a particle concentration of 90 kg/m3, the average wear rate at a groove spacing of 7 mm is ~0.63 × 10−4 kg/s∙m2, and the wear area is mainly found in the middle of the blade. The reason why the bionic blade improves the anti-wear performance of the pump is due to the reverse vortex zone in the groove, which changes the particle trajectory and collision frequency. The bionic grooves with a diameter of 2 mm and a spacing of 7 mm significantly reduce the average wear rate of the pump at different particle concentrations, while maintaining hydraulic performance.

Effect of Bionic Nonsmooth Surface Vane on the Antiwear Characteristics of Double-Vane Pump

In order to improve the antiwear characteristics of the double-vane self-priming pump, the surface structure of the Scapharca subcrenata was extracted and reconstructed according to bionic principles. Three types of nonsmooth surface models were established at the outlet end of the suction surface of the vanes, which is the most severely worn in the double-vane pump. The external characteristics, pressure field distribution, wear area distribution, and wear degree of the volute and vanes at different concentrations of nonsmooth vane structure were investigated by numerical simulation to reveal the mechanism of the nonsmooth surface structure of the wear characteristics of the vanes. The results show that the head and efficiency of pumps with four different vanes decrease and the average wear rate increases as the particle concentration increases. The different vane structures have a very small effect on the wear resistance of the volute, but a larger effect on vane wear. The circular nonsmooth surface structure, which reduces the low pressure area of the inlet section of the impeller while ensuring a smaller drop in head and efficiency, produces the best antiwear effect and improves the antiwear performance of the double-vane pump.

Nanostructured Coatings: Review on Processing Techniques, Corrosion Behaviour and Tribological Performance

Corrosion and tribology are surface phenomena. Modifying surfaces of materials without resorting to altering their bulk properties is an effective route to alleviate corrosion, friction and wear, encountered in engineering applications. With the advancements in the field of nanotechnology, surface protective coatings with nanomaterials can be readily developed to explore their functionality in mitigating chemical/physical damage of surfaces. Surface protection enhances performance and operating lifetimes of industrial machinery components. This review presents insights on various types of recently developed nanostructured coatings, their synthesis routes, corrosion behaviour and tribological performance. It provides the state-of-the-art information on the development of nanostructured coatings, namely, ceramic coatings, metallic coatings and nanocomposite coatings with metal and polymer matrices. Biomimetic approaches in making nanostructured coatings and challenges encountered in the development of nanostructured coatings are highlighted.

The Effect of Complex Emulsifier on the Structure of Tung Oil and Phenolic Amides Containing Microcapsules and Its Anti-Fouling and Anti-Corrosion Performances

In this study, the urea-formaldehyde (UF)-tung oil solution of phenolic amide (PA) microcapsules to realize anti-fouling and anti-corrosion integration was synthesized by the in situ polymerization method. The compounds and structures were optimized by investigating six kinds of different emulsifiers. The results showed that high-core-content and narrow-particle-size-distribution microcapsules could be synthesized with sodium dodecyl benzene sulfonate (SDBS)/polyvinyl alcohol (PVA), and the core content of the microcapsules was 75 wt% at microcapsule sizes from 24.07 to 71.33 µm. The results of self-healing coatings showed that when the content of microcapsules in the coating exceeded 10 wt%, the healing agent released from the scratched surface could cover the naked metal effectively, which could pass a 7 day neutral salt spray test without rust at the scratched area. A sufficient dose anti-fouling agent can be provided to prevent diatoms and mussels from adhering. The present work shows that the complex emulsifier can better control the particle size distribution and microstructure of the microcapsules, and the admixture of the microcapsules into the resin epoxy coating can realize excellent anti-corrosion and anti-fouling functions.

Preparation and Modification Technology Analysis of Ionic Polymer-Metal Composites (IPMCs)

As a new type of flexible smart material, ionic polymer-metal composite (IPMC) has the advantages of being lightweight and having fast responses, good flexibility, and large deformation ranges. However, IPMC has the disadvantages of a small driving force and short lifespan. Based on this, this paper firstly analyzes the driving mechanism of IPMC. Then, it focuses on the current preparation technology of IPMC from the aspects of electroless plating and mechanical plating. The advantages and disadvantages of various preparation methods are analyzed. Due to the special driving mechanism of IPMC, there is a problem of short non-aqueous working time. Therefore, the modification research of IPMC is reviewed from the aspects of the basement membrane, working medium, and electrode materials. Finally, the current challenges and future development prospects of IPMC are discussed.

Slime-Groove Drag Reduction Characteristics and Mechanism of Marine Biomimetic Surface

With the development of science and technology, energy consumption and demand continue to increase, and energy conservation and consumption reduction have become the primary issue facing the world. Improving the energy efficiency of ships not only helps reduce fuel consumption but also reduces carbon dioxide emissions, which is an important guarantee for the green development of the ocean and the maintenance of ecological balance. Through natural selection and adaptation to the environment after evolution, the body surface of organisms generates a variety of ways to resist adhesion and resistance of Marine organisms. Through the study of fish organisms, it is found that the body surface of general fish has mucus, which can effectively reduce the friction resistance of the body surface of fish subjected to seawater. In addition, the grooves on the body surface also help to reduce the resistance between swimming organisms and fluids. Based on the principle of bionics, the drag reduction characteristics and mechanism of fish surface mucus were analyzed. The drag reduction mechanism of bionic nonsmooth surface is analyzed from the aspect of body surface structure. On the basis of the two approaches, the characteristics and mechanism of slime and groove codrag reduction on the surface of Marine organisms were discussed in depth, so as to obtain a better new drag reduction method and provide reference for subsequent related research.

Effects of tralopyril on histological, biochemical and molecular impacts in Pacific oyster, Crassostrea gigas

Recently, the toxic effects of tralopyril, as a new antifouling biocide, on aquatic organisms have aroused widespread attention about the potential toxicity. However, the mechanism of tralopyril on marine mollusks has not been elaborated clearly. In this study, the histological, biochemical and molecular impacts of tralopyril on adult Crassostrea gigas were investigated. The results indicated that the 96 h LC50 of tralopyril to adult Crassostrea gigas was 911 μg/L. After exposure to tralopyril (0, 40, 80 and 160 μg/L) for 6 days, the mantle mucus secretion coverage ratio of Crassostrea gigas was increased with a dose-dependent pattern. Catalase (CAT) activity was significantly increased, amylase (AMS) activity, acid phosphatase (ACP) activity and calcium ion (Ca²⁺) concentration significantly decreased. Meanwhile, integrated biomarker responses (IBR) index suggested that higher concentrations of tralopyril caused severer damage to Crassostrea gigas. In addition, the mRNA expression levels of biomineralization related genes in the mantle were significantly upregulated. Collectively, this study firstly revealed the histological, biochemical and molecular impacts of tralopyril exposure on adult Crassostrea gigas, which provided new insights for understanding the toxicity of tralopyril in marine mollusks.

Drag Reduction Using Additives in Smooth Circular Pipes Based on Experimental Approach

Reduction of fluid resistance using the rheological characteristics of a polymer-surfactant solvent is research that contains many aspects, such as the theory of the drag reduction process, historical journey, and ongoing current research development. Many studies have been conducted, but it is challenging to know all existing and new research threads. The present investigation was conducted using literature studies regarding drag reducing agents. This research will also discuss the characteristics of flowing fluids and their effects on the velocity profile with friction factor of flowing fluids in smooth circular straight pipe geometries based on experimental, theoretical approaches. It concludes with aspects of research conducted around reducing drag using drag reducing agents, ideas about innovations, structuring overlook in testing, and modification of the fluid flow state.

Molecular Insight into the Possible Mechanism of Drag Reduction of Surfactant Aqueous Solution in Pipe Flow

The phenomenon of drag reduction (known as the “Toms effect”) has many industrial and engineering applications, but a definitive molecular-level theory has not yet been constructed. This is due both to the multiscale nature of complex fluids and to the difficulty of directly observing self-assembled structures in nonequilibrium states. On the basis of a large-scale coarse-grained molecular simulation that we conducted, we propose a possible mechanism of turbulence suppression in surfactant aqueous solution. We demonstrate that maintaining sufficiently large micellar structures and a homogeneous radial distribution of surfactant molecules is necessary to obtain the drag-reduction effect. This is the first molecular-simulation evidence that a micellar structure is responsible for drag reduction in pipe flow, and should help in understanding the mechanisms underlying drag reduction by surfactant molecules under nonequilibrium conditions.

Deducing the Relation between Viscosity and Oil-Induced Structural Changes of Viscoelastic Surfactants Using a Kinetic Approach

The present study relates viscosity reduction with time of a wormlike micellar solution to the micellar transitions that occur with time in the presence of three n-alkanes, namely, n-decane, n-dodecane, and n-hexadecane. Steady-shear rheology and small-angle X-ray scattering were used to deduce the relationship. The effect of n-alkane concentration was tested only with n-decane. There were at most three stages of viscosity reduction, which appeared in the following order: (i) the rising viscosity stage, (ii) the fast viscosity reduction stage, and (iii) the low-viscosity stage. The stages and rates of viscosity transition depended on the type of micelles present and the degree of micelle entanglement. Moreover, the rate of transition increased when the n-alkane concentration was increased and when the n-alkane molecular mass was reduced. n-Hexadecane induced only the first two stages of transition at a slower rate compared to the other oils.

Transformations of wormlike surfactant micelles induced by a water-soluble monomer

HYPOTHESIS

Wormlike surfactant micelles (WLMs) are prospective as nanoreactors for micellar copolymerization of hydrophilic and hydrophobic monomers. Hydrophilic monomers can destroy WLMs. Large size and cylindrical shape of micelles can be preserved by high salt content favoring closer packing of surfactant heads.

EXPERIMENTS

The effect of a water-soluble monomer (acrylamide) on the structure and rheological properties of giant WLMs of an anionic surfactant potassium oleate at different salt content was investigated by combined experimental (SANS, rheometry, fluorescence and NMR spectroscopy, tensiometry) and molecular dynamics simulations studies.

FINDINGS

At low salt content, when WLMs are linear, acrylamide induces their shortening and transformation into spherical micelles as a result of its incorporation into the micellar corona, leading to the drop of viscosity. At high salt content providing branched WLMs, monomer first triggers their transition to long linear chains, which enhances the viscoelasticity, and then to rods. This is the first report showing that the effect of monomer on the rheological properties is quite different for linear and branched micelles. Using branched micelles allows preserving large WLMs at high water-soluble monomer content, which is favorable for their use as nanoreactors for synthesis of copolymers with high degree of blockiness, which give mechanically tough polymer gels.

Mechanical properties and application analysis of spider silk bionic material

Spider silk is a kind of natural biomaterial with superior performance. Its mechanical properties and biocompatibility are incomparable with those of other natural and artificial materials. This article first summarizes the structure and the characteristics of natural spider silk. It shows the great research value of spider silk and spider silk bionic materials. Then, the development status of spider silk bionic materials is reviewed from the perspectives of material mechanical properties and application. The part of the material characteristics mainly describes the biocomposites based on spider silk proteins and spider silk fibers, nanomaterials and man-made fiber materials based on spider silk and spider-web structures. The principles and characteristics of new materials and their potential applications in the future are described. In addition, from the perspective of practical applications, the latest application of spider silk biomimetic materials in the fields of medicine, textiles, and sensors is reviewed, and the inspiration, feasibility, and performance of finished products are briefly introduced and analyzed. Finally, the research directions and future development trends of spider silk biomimetic materials are prospected.

Research Strategies to Develop Environmentally Friendly Marine Antifouling Coatings

There are a large number of fouling organisms in the ocean, which easily attach to the surface of ships, oil platforms and breeding facilities, corrode the surface of equipment, accelerate the aging of equipment, affect the stability and safety of marine facilities and cause serious economic losses. Antifouling coating is an effective method to prevent marine biological fouling. Traditional organic tin and copper oxide coatings are toxic and will contaminate seawater and destroy marine ecology and have been banned or restricted. Environmentally friendly antifouling coatings have become a research hotspot. Among them, the use of natural biological products with antifouling activity as antifouling agents is an important research direction. In addition, some fouling release coatings without antifoulants, biomimetic coatings, photocatalytic coatings and other novel antifouling coatings have also developed rapidly. On the basis of revealing the mechanism of marine biofouling, this paper reviews the latest research strategies to develop environmentally friendly marine antifouling coatings. The composition, antifouling characteristics, antifouling mechanism and effects of various coatings were analyzed emphatically. Finally, the development prospects and future development directions of marine antifouling coatings are forecasted.

Synthesis and Evaluation of Zwitterionic Surfactants Bearing Benzene Ring in the Hydrophobic Tail

Surfactant tolerance in the presence of mono and divalent reservoir ions, as well as the solubility of surfactant in high salinity and low salinity brine, are the two major requirements for any surfactant that is subjected to oilfield application. Herein, six poly(ethylene oxide) zwitterionic surfactants having different ionic headgroups and hydrophobic tail were synthesized for oilfield applications. They were characterized by various instrumental techniques (Fourier-transform infrared spectroscopy (FTIR), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF-MS), Nuclear Magnetic Resonance (NMR)) and the combination of these techniques allowed for us to deduce the structure. All of the surfactants revealed prominent solubility in high salinity and low salinity brine due to the presence of ethoxy units between the aromatic ring and amide group. The surfactant samples were oven aged for 90 days at reservoir temperature and a clear solution implies their excellent aqueous stability. Rendering to thermal gravimetric results, decomposition of surfactants was found to occur around 300 °C, which is higher than the reservoir temperature (≥90 °C). It was observed that the hydrophilic headgroup has no significant impact on the critical micelle concentration and other surface properties. However, the hydrophobic tail bearing benzene ring significantly alters the critical micelle concentration and other surface properties.

Technical Characteristics and Wear-Resistant Mechanism of Nano Coatings: A Review

Nano-coating has been a hot issue in recent years. It has good volume effect and surface effect, and can effectively improve the mechanical properties, corrosion resistance and wear resistance of the coatings. It is important to improve the wear resistance of the material surface. The successful preparation of nano-coatings directly affects the application of nano-coatings. Firstly, the preparation methods of conventional surface coatings such as chemical vapor deposition and physical vapor deposition, as well as the newly developed surface coating preparation methods such as sol-gel method, laser cladding and thermal spraying are reviewed in detail. The preparation principle, advantages and disadvantages and the application of each preparation method in nano-coating are analyzed and summarized. Secondly, the types of nano-coating materials are summarized and analyzed by inorganic/inorganic nanomaterial coatings and organic/inorganic nanomaterial coatings, and their research progress is summarized. Finally, the wear-resistant mechanism of nano-coatings is revealed from three aspects: grain refinement, phase transformation toughening mechanism and nano-effects. The application prospects of nano-coatings and the development potential combined with 3D technology are prospected.

Poly(Oxyethylene)-Amidoamine Based Gemini Cationic Surfactants for Oilfield Applications: Effect of Hydrophilicity of Spacer Group

Thermal stability, salt tolerance, and solubility in normal and high salinity brine are the major requirements for any surfactant designed for oilfield applications because the surfactant stays in a non-ambient environment inside the reservoir for a long period of time. Herein, a series of new gemini cationic surfactants (GSs) with varying spacer hydrophilicity were synthesized and elucidated using MALDI-ToF-MS, NMR (1H, 13C), as well as FTIR spectroscopy. GSs found to be soluble in normal as well as high salinity brine and aqueous stability tests revealed that GSs possess the ability to retain their structural integrity at high salinity and high temperature conditions because no suspension formation or precipitation was detected in the oven aged sample of GSs at 90 °C for 30 days. Thermal gravimetric analysis displayed a higher decomposition temperature than the real reservoir temperature and the GS with a secondary amine spacer exhibited high heat stability. The significant reduction in surface tension and critical micelle concentration was observed using 1 M NaCl solution in place of deionized water. The difference in surface tension and critical micelle concentration was insignificant when the 1 M NaCl solution was replaced with seawater. The synthesized surfactants can be utilized for oilfield applications in a challenging high temperature high salinity environment.