Modified Silica Nanoparticles Research Articles

Zwitterionic polymer grafted nano-SiO2 as fluid loss agent for high temperature water-based drilling fluids

With the advancement of ultra-deep well technology, there has been an increased demand for enhanced high-temperature stability in water-based drilling fluids. To address this challenge, this study has developed a novel polymer nanocomposite (AAND-S) to augment the thermal stability of polymeric fluid loss additives in WBDF. AAND-S was synthesized through aqueous radical polymerization, consisting of zwitterionic polymers with rigid anionic groups and strong cationic adsorption groups, grafted with modified silica nanoparticles. The structure of AAND-S was characterized by infrared and thermogravimetric analyses. The performance of drilling fluids containing AAND-S was evaluated under high-temperature aging conditions at 220 ℃. Notably, the Herschel-Bulkley model provided a more accurate description of the behavior of this non-Newtonian fluid. Specifically, after aging at 220 ℃, the fluid loss of the base mud with AAND-S was reduced to 12.25 mL. Additionally, AAND-S exhibited good salt tolerance up to 25 % NaCl solution. The compatibility of AAND-S was also excellent, enabling it to synergistically interact with other drilling fluid additives to form an efficient drilling fluid system that effectively minimized fluid loss. The mechanism of action of AAND-S was investigated through total organic carbon analysis, zeta potential measurements, and particle size analysis. It was found that AAND-S enhanced the adsorption capacity of bentonite, improving the stability of the colloidal solution and leading to a more uniform particle size distribution. Further SEM microstructural analysis confirmed that the incorporation of AAND-S facilitated the formation of high-quality filter cakes with a dense surface and minimal permeability at elevated temperatures. In conclusion, AAND-S, as a high-performance fluid loss additive, is anticipated to play a significant role in drilling operations in ultra-high temperature formations.

Molecular Dynamics Simulation of Mechanical and Tribological Properties of Ultrahigh Molecular Weight Polyethylene Enhanced by Modified Silica Nanoparticles

Molecular Dynamics Simulation of Mechanical and Tribological Properties of Ultrahigh Molecular Weight Polyethylene Enhanced by Modified Silica Nanoparticles

Superhydrophobic asymmetric pH-responsive soft actuators: Implications for the development of anti-fouling medical devices

Biomedical engineering strives for innovation to enhance the safety and effectiveness of medical tools, such as catheters and stents that need to be operated in confined spaces, with precise drug delivery control and should possess anti-fouling properties. Soft actuators with superhydrophobic surfaces can provide adaptable shape change together with non-fouling attributes required for medical devices. In this study, we have developed a Janus film with a hydrophilic solvent-responsive bottom and superhydrophobic top surface using a self-assembly strategy. The devised new strategy involves the dispersal of modified silica nanoparticles into a homogeneous solution, where they were segregated from the polymer matrix and self-assembled to form a superhydrophobic layer on the surface with a water contact angle of >150°. The resulting asymmetric actuator demonstrated bidirectional actuation in solvents with extreme pH values i.e., pH 1 and 13. It could be tailored for specific hydrophilicity by adjusting the ratio of dispersed superhydrophobic and hydrophilic silica nanoparticles in the polymer solution. These films exhibited exceptional chemical stability against strong acids, alkaline solutions, ethanol, and salt, as well as mechanical stability against abrasion from sandpaper. In vitro studies confirmed their superior anti-fouling and anti-bacterial properties. Furthermore, actuation of printed 3D structures with different patterns was demonstrated, showcasing the possibility of developing these superhydrophobic asymmetric surfaces via 3D printing and their potential as cardiovascular stents.

Interfacial Rheological Investigation of Modified Silica Nanoparticles with Different Alkyl Chain Lengths at the n-Octane/Water Interface.

The interfacial dilational rheology of silica nanoparticles (NPs) directly reflects the relationship between surface structure and interfacial behaviors in NPs, which has attracted significant attention in various industrial fields. In this work, modified silica nanoparticles (MNPs) with various alkyl chain lengths were synthesized and systematically characterized using Fourier transform infrared spectra, Zeta potential, and water contact angle measurements. It was found that the MNPs were successfully fabricated with similar degrees of modification. Subsequently, the interfacial behaviors of the MNPs in an n-octane/water system were investigated through interfacial dilational rheological experiments. The length of the modified alkyl chain dominated the hydrophilic-lipophile balance and the interfacial activity of the MNPs, evaluated by the equilibrium interfacial tension (IFT) variation and dilational elasticity modulus. In the large amplitude compression experiment, the balance between the electrostatic repulsion and interfacial activity in the MNPs was responsible for their ordered interfacial arrangement. The MNPs with the hexyl alkyl chain (M6C) presented the optimal amphipathy and could partly overcome the repulsion, causing a dramatic change in surface pressure. This was further confirmed by the variations in IFT and dilational elasticity during the compression path. The study provides novel insights into the interfacial rheology and interactions of functionally modified NPs.

Preparation of polyurethane shell microcapsules containing isocyanate core by Pickering emulsion method using modified silica nanoparticles and investigation of their self-healing performance

Encapsulating repair agents are increasingly popular for repairing coating damage, with capsules being a common method to address surface scratches by releasing healing liquid into the fissure. However, creating microcapsules that are durable against environmental factors remains a key concern. Current research focuses on advancements in encapsulating healing agents and their production methods, particularly emphasizing the integration of capsules into coatings for external self-healing purposes. Polyurethane capsules containing isophorone diisocyanate were synthesized using the Pickering emulsion method with modified silica as a Pickering emulsion stabilizer in three different percentages and then dispersed in urea formaldehyde at varying weight percentages. The self-healing properties of this coating were then studied. Fourier transform infrared spectroscopy (FTIR), Soxhlet extraction, and thermogravimetric analysis (TGA) were performed on the samples to ensure the success of the encapsulation process. The morphology of the capsules was investigated using field emission scanning electron microscopy (FE-SEM), revealing that the synthesized capsules possess a spherical shape and are adequately spaced apart. These capsules were spherical at micron scales, with differences observed based on the quantity of stabilizing nanoparticles employed. Furthermore, the capsules demonstrated robust thermal stability, as evidenced by the increase in IPDI evaporation temperature from approximately 140 °C to 240 °C.Immersion test results in saltwater solutions showed that coatings containing pickering capsules exhibited better corrosion resistance, further validating the success of the research. The shell strength of the capsules prepared using the Pickering method was increased, enhancing the stability of the microcapsules during the mixing process with the resin and demonstrating self-healing properties. These findings have significant practical implications, as they demonstrate the potential to improve the durability and lifespan of coatings in various applications.

Superamphiphobic coating prepared via a two-step spray method: An effective coating for reducing VOCs emission from crude oil tank

In the petrochemical industry, crude oil adhesion in storage tanks leads to volatilization of volatile organic compounds (VOCs), causing environmental harm and economic losses. Superamphiphobic coatings show promise in addressing this issue, but current options face challenges like complexity, limited durability, and poor corrosion resistance. This work introduces a durable and corrosion-resistant superamphiphobic coating on Q235 carbon steel using the "paint + adhesives" two-step spray method. The first layer comprises polytetrafluoroethylene (PTFE) and epoxy resin (E-44), while the second layer consists of fluorine modified silica nanoparticles (F-SiO2). The numerous and homogeneously dispersed fluorine on the coating imparts excellent liquid-repelling properties for both water and crude oil, with a water contact angle of 164.1 ± 2.4° and a sliding angle of 1.1 ± 0.1°, as well as a crude oil contact angle of 172.1 ± 0.9° and a sliding angle of 2.5 ± 0.5°. Systematic stability tests confirm the coating's mechanical and chemical stability, suggesting its potential in practical applications. Importantly, a crude oil tank with our superamphiphobic coating can reduce non-methane hydrocarbon (NMHC) volatilization by 77.4 % ± 7.8 % compared to an uncoated tank. This research provides a superamphiphobic coating to reduce crude oil loss and VOC volatilization in petrochemical enterprises, showing significant contribution to environmental sustainability.

Application of Organo-Modified Silica Nanoparticles to Improve the Load-Bearing Capacity of Bonded Joints of Dissimilar Steel Substrates

The paper deals with the joining of dissimilar steels by adhesive bonding. The base materials for the experimental work were deep-drawn low-carbon steel DC04, and hot-dip galvanized HSLA steel HX340LAD+Z. Adhesive bonding was performed using rubber-based and epoxy-based adhesives. The research aimed to verify the importance of surface preparation of steel substrates using a formulation with organically modified silica nanoparticles and epoxy organic functional groups, where one end of the functional group can be incorporated into the organic binder of the coating material and the other end can be firmly bonded to substances of an inorganic nature (metals). Since the binder base of adhesives is very similar to that of coatings, verifying the performance of this surface preparation when interacting with the adhesive is necessary. The load-bearing tensile shear capacity of single-lapped joints and the resistance of the joints against corrosion-induced disbanding in a climate chamber were tested. The energy dissipated by the joints up to fracture was calculated from the load-displacement curves. Bonded joints with organosilane were compared with joints without surface preparation and joints prepared by chroman-free zirconate passivation treatment. Exposure of the joints in the climatic chamber did not cause a relevant reduction in the characteristics of the joints. Organosilicate formulation was proved effective when bonding ungalvanized steels with a rubber-based structural adhesive, where it improves the bond quality between the adhesive and the substrate.

Development of superhydrophobic fractal surfaces using Silica nanoparticles based on polylactic acid through molding technique

This research introduces a novel approach to creating superhydrophobic surfaces on polymer substrates. The objective is to develop a general method for producing various types of superhydrophobic polymer surfaces using modified nanoparticles, as well as making Unplasticized PolyVinyl Chloride(UPVC) and polylactic acid hydrophobic. To achieve this goal, we investigate the circulation of a rotating cover, pressure, and pressure time. We embed modified silica nanoparticles onto UPVC boards, which confirms surface hydrophobicity with a contact angle of 155° and a sliding angle of 6–7° for water droplets. Under specific conditions, including a suspension concentration of 10 g/L, coating time of 5 seconds, temperature of 155°C, rotation speed of 400 rpm, and pressure of 2 MPa with a pressure time of 4 minutes, we achieve superhydrophobicity on PVC boards, resulting in contact angles of 150–160°. Additionally, we find that the sliding angle of water droplets is less than 10°.

Fabrication of superhydrophobic surface by spraying hydrophobically modified silica nanoparticles on partially cured polyurethane paint

ABSTRACT There is an increasing demand for superhydrophobic surfaces due to their unique properties like self-cleaning, anti-icing, corrosion resistance, etc. The development of polyurethane (PU)-based superhydrophobic coating has garnered significant attention for aircraft applications. Polyurethane (PU) topcoat is widely used in aircraft and is hydrophilic in nature with a water contact angle (WCA) of 75 ± 3°. In the present work, a hydrophilic PU clear coat on aircraft-grade aluminum substrate is transformed to a superhydrophobic (SHP) surface by spraying environmentally friendly hydrophobically modified silica nanoparticles (HSiNps) oonto a PU layer that was partially cured in a hot air oven at 60°C for 1.5 h. The SHP surface exhibited a WCA of 162 ± 3° and a sliding angle (SA) of 8 ± 3°. With the incorporation of HSiNps, micro – nano dual-scale surface roughness is created and the surface roughness of the PU coating is increased from 0.35 to 2.42 µm. The coating exhibits good adhesion (5B) with excellent water repelling property and remains thermally stable and superhydrophobic even after subjecting it to 100°C for one week. Durability of the coatings is studied by immersing the coatings in various liquids. The retention of superhydrophobic property after anti-fogging, water sprinkler, and sand paper abrasion tests further demonstrate the robustness of the coating.

Modified silica nanoparticles stabilized foam for enhanced oil recovery

Foam has been successfully used to improve mobility control in the process of enhanced oil recovery, yet the instability of foam limits its application. Modified nanoparticles with varying wettability were prepared by reacting 3-methacryloxypropyltrimethoxysilane (KH570) with spherical SiO2 nanoparticles in this study. Fourier transform infrared (FTIR) spectra and the measured contact angles were used to characterize the surface properties of the modified SiO2 particles, and the foam stabilization effects of wettability SiO2 were compared. Pore-scale visualization experiments were conducted using a 2D micromodel to identify the prevailing enhanced oil recovery (EOR) mechanisms of modified nano SiO2-Sodium alpha-olefin Sulfonate (AOS) foam flooding. The results indicate that modified SiO2 effectively improves foam stability by adsorbing on the bubble surface and forming a mesh-like structure. The optimum contact angle of the particles is approximately 60°, resulting in a significant increase in drainage half-life by 29.4% compared to foam stabilized only by AOS. Additionally, Foam stabilized by modified SiO2 demonstrates superior dynamic stability and deformation resistance. The modified SiO2 stabilized foam exhibits enhanced interfacial viscoelasticity and plugging and profile control performance, surpassing AOS foam in displacing more residual oil in dead-end pores. The oil recovery of the micro model was determined by ImageJ software. KH570@SiO2 (0.2wt%)-AOS (0.2wt%) foam flooding increased the recovery by 8.7% compared to AOS (0.2wt%) foam flooding.

Regenerative Superhydrophobic Coatings for Enhanced Performance and Durability of High-Voltage Electrical Insulators in Cold Climates.

Superhydrophobic coatings can be a suitable solution for protecting vulnerable electrical infrastructures in regions with severe meteorological conditions. Regenerative superhydrophobicity, the ability to regain superhydrophobicity after being compromised or degraded, could address the issue of the low durability of these coatings. In this study, we fabricated a superhydrophobic coating comprising hydrophobic aerogel microparticles and polydimethylsiloxane (PDMS)-modified silica nanoparticles within a PDMS matrix containing trifluoropropyl POSS (F-POSS) and XIAMETER PMX-series silicone oil as superhydrophobicity-regenerating agents. The fabricated coating exhibited a static contact angle of 169.5° and a contact angle hysteresis of 6°. This coating was capable of regaining its superhydrophobicity after various pH immersion and plasma deterioration tests. The developed coating demonstrated ice adhesion as low as 71.2 kPa, which remained relatively unchanged even after several icing/de-icing cycles. Furthermore, the coating exhibited a higher flashover voltage than the reference samples and maintained a minimal drop in flashover voltage after consecutive testing cycles. Given this performance, this developed coating can be an ideal choice for enhancing the lifespan of electrical insulators.

Improvement of the anti-corrosion coating properties of waterborne epoxy resin with the incorporation of fluoropolymer-modified silica nanofillers

The objective of this research was to enhance the corrosion resistance and mechanical properties of silica nanoparticles modified by a fluoropolymer (polyhexafluorobutyl acrylate, PHFBA) by incorporating them into a waterborne epoxy resin (WEP) coating system. Initially, polyhexafluorobutyl acrylate (PHFBA)-modified silica nanoparticles were synthesized using a two-step method, involving the grafting of 3-(isobutylloxy) propyl trimethoxysilane (KH570) onto SiO2 to produce SiO2@KH570, followed by a random copolymerization of SiO2@KH570 with hexafluorobutyl acrylate (HFBA) to obtain the fluoropolymer-modified SiO2 (FxSiO2). Subsequently, the chemical structure and elemental composition of SiO2, as well as the prepared SiO2@KH570 and FxSiO2 nanoparticles, were comprehensively investigated. Moreover, FxSiO2/WEP composite coatings with different amounts of fluoropolymer-modified nanofillers and x-F5SiO2/WEP composite coatings with varying amounts of F5SiO2 nanofillers were prepared and characterized. The findings revealed that the functionalized FxSiO2 exhibits superior dispersion, interface, and size effects, significantly enhancing the overall performance of WEP coatings. Notably, when 0.1 wt% F5SiO2 nanofiller was incorporated, the resulting 0.1-F5SiO2/WEP composite coating demonstrated a considerable impedance modulus (1.171 × 108 Ω∙cm2), relatively low water absorption rate (about 11 % after 20 d of immersion in water), and robust mechanical properties: a tensile strength of 6.07 MPa and an elongation at break of 37.36 %. Moreover, the hardness and adhesion of the composite coating remain unaltered. Furthermore, after 20 days of salt spray testing, the electrochemical impedance still reached 8.765 × 106 Ω∙cm2, indicating a favorable long-term anti-corrosion capability. Consequently, the integration of fluoropolymer-modified nanoparticles in water-based epoxy resins holds great potential.

A loose polyethersulfone hybrid nanofiltration membrane incorporated with polyethyleneimine-decorated silica nanoparticles for highly-efficient dye/salt separation

Loose nanofiltration (LNF) is a newly-developing technology for desalting dye-containing saline effluents, but suffers from membrane materials with low permeance and poor dye/salt separation selectivity. Herein, a hybrid polyethersulfone (PES) LNF membrane for dye/salt separation was prepared via a nonsolvent-induced phase inversion method, which was carried out using polyethyleneimine (PEI)-modified silica nanoparticles as a dopant. This design not only featured a hybrid PES LNF membrane with high porosity and small mean pore size, but also partially neutralized its charge and enhanced its hydrophilicity. Hybrid PES LNF membrane from a 21-wt% PES solution with 3-wt% PEI-decorated silica nanoparticles addition was demonstrated to achieve high water permeance (92.0 L m−2 h−1 bar−1) and dyes retention ratio (98.4 % for Congo Red, 98.8 % for Nile Blue A, and 95.1 % for Methyl Blue) accompanied with fully-pass for various salts (Na2SO4, NaCl, MgCl2 and CaCl2). In addition, the hybrid membrane exerted excellent resistances to strong acidic, oxidative and hot water (90 °C) environments and exhibited a pH-sensitive permeability. Multicycle test revealed that the hybrid membrane had high permeance recovery ratio (>92.8 %) and maintained its high dye retention and complete salt permeation even after 10 cycles, manifesting its outstanding fouling resistance and recyclability. Besides, the hybrid membrane repelled 92.6 % of dyes from a simulated wastewater consisting of multiple industry-applied direct dyes and salts after 12 h consecutive test, but allow 100 % of mixed salts passing through the membrane, proving its practical applicability to industrial dyeing wastewater. This study provided a simple and economically feasible route to high-performance LNF membrane production for dye/salt separation, thus popularizing LNF process in dyeing wastewater treatment, organic products purification, and resource recovery.

Interfacial Behaviors and Oil Detachment Mechanisms by Modified Silica Nanoparticles: Insights from Molecular Simulations.

Surfactant flooding has been considered as a promising approach for chemically enhanced oil recovery (EOR). However, this technique encounters several limitations, such as high costs, environmental concerns, and reduced efficiency under high-temperature and high-salinity reservoir conditions. Recently, nanoparticles have also been proposed as an alternative for EOR due to their superior properties compared with surfactants. This research employs molecular dynamics simulations to explore the impact of modified SiO2 nanoparticles on oil-water interfacial behaviors and the detachment of oil droplets from an oil-wet surface. The simulation results reveal that modified nanoparticles, featuring hydrophilic and hydrophobic functional groups, have slight impacts on interfacial tension reduction of the oil-water interface. Nanoparticles with varying degrees of modification exhibit distinct positions within the interface, consequently influencing the thickness of the interfacial layer. Notably, the interactions among the nanoparticles, oil molecules, and surface facilitate the formation of a water channel, thereby enhancing the process of oil detachment. Comparative analysis indicates that in terms of oil displacement efficiency, the thickness of the interfacial layer has a more significant impact than interfacial tension reduction. Furthermore, to elucidate the mechanisms of modified nanoparticles enhancing the oil recovery rate, the interaction energies among the oil droplet, nanoparticles, water, and surface are analyzed. The molecular-level insights derived from this investigation could provide valuable guidance for the design of modified nanoparticles tailored to EOR applications.

Bioaccessibility of chlorogenic acid and curcumin co-encapsulated in double emulsions with the inner interface stabilized by functionalized silica nanoparticles

The aim of this study was to evaluate the bioaccessibility of chlorogenic acid (CA) and curcumin co-encapsulated in Pickering double emulsions (DEs) with the inner interface stabilized by hydrophobically modified silica nanoparticles with myristic acid (SNPs-C14) or tocopherol succinate (SNPs-TS). Both SNPs-C14 and SNPs-TS showed contact angles > 90°. Pickering W1/O emulsions were formulated with 4 % of both types of SNPs. Pickering DEs showed higher creaming stability (5–7 %, day 42) and higher CA encapsulation efficiency (EE; 80 %) than control DE. The EE of curcumin was > 98 % in all the DEs. CA was steadily released from Pickering DEs during digestion, achieving bioaccessibility values of 58–60 %. Curcumin was released during the intestinal phase (∼80 % bioaccessibility in all DEs). Co-loaded DEs showed similar bioaccessibility for CA and curcumin than single-loaded. SNPs-C14 and SNPs-TS were suitable to stabilize the W1:O interface of DEs as co-delivery systems of bioactive compounds with health-promoting properties.

Preliminary Study on the Modification of Quantum Dots/Geothermal Silica Nanocomposites with Breast Cancer Antibody (MUC-1)

In this research, a silica-based nanosensor is synthesized using the sol-gel method and subsequently modified with quantum dots and MUC-1 antibody to detect MCF7, a cell line commonly found in breast cancer. Synthesis of silica nanoparticles was conducted through the sol-gel process using NaOH and HCl. The characterization using surface area analysis shows that geothermal silica based nanoparticles exhibit specific size of 31.2 nm with specific surface area of 192.37 m2/g. The nanoparticles were then modified using Cd-based Carboxyl Quantum dots to give fluorescence properties, obtaining SiNP@QD. Characterization was performed using UV-Vis and fluorescence spectroscopy to understand the photostability of nanoparticles in PBS buffer in various concentrations. The fluorescent nanoparticles were then immobilized with MUC-1 antibody and the successful conjugation was confirmed with FTIR showing peaks at 1548 and 1637 cm−1 corresponding to the amide I and amide II stretching vibration, respectively. The MUC-1 antibody modified silica nanoparticles is potential to be applied as nanosensor for the optical detection of MCF-7 cell line as one of breast cancer biomarkers.

Advances in modified silica nanoparticles utilization for various applications: Now and future

The review article explores the multifaceted applications of silica nanoparticles (SNPs) across diverse industries, emphasizing their catalytic role in transformative advancements. Green nanotechnology principles are crucial for sustainable SNP synthesis, with a focus on utilizing natural extracts and bio-agents. Standardization and enhanced collaboration between industry and academia are pivotal for realizing the broader potential of SNPs. In the biomedical realm, SNPs exhibit exceptional capabilities in drug delivery and diagnostics, promising significant medical advancements. Safe integration necessitates collaborative efforts in safety assessments, long-term studies, and standardized testing. The exploration of SNP-based advanced coatings hints at industry-specific applications, with a recommendation for continued research into new capabilities and compatibility. SNPs in Li-ion batteries show promise for energy storage, urging further investigation into scalability and long-term performance. Agriculture benefits from SNP applications in precision farming, emphasizing the need for environmentally conscious formulations. In nanocomposite materials, SNPs enhance mechanical properties, advocating collaborative research for standardization and optimization. The adaptability of SNP-based smart coatings in aerospace and automotive industries requires exploration of new functionalities and seamless integration. In conclusion, SNPs hold promising prospects in healthcare, energy storage, and agriculture, emphasizing the necessity of collaborative efforts, sustained research, and a commitment to responsible and innovative SNP integration for a technologically advanced and environmentally conscious future.

A highly reactive soybean oil-based superhydrophobic polyurethane film with long-lasting antifouling and abrasion resistance.

Superhydrophobic polyurethanes offer robust hydrophobicity and corrosion resistance. However, it is essential to consider the durability and environmental constraints associated with these materials. This study prepared a bio-based superhydrophobic polyurethane coating film using epoxidized soybean oil, superhydrophobically modified silica nanoparticles, and OH-PDMS-OH as surface modifiers. The coating film exhibited sustained super-hydrophobicity and an excellent antifouling effect for pu-erh tea and edible oils, among other substances, after 14 days of immersion in solutions with different pH values, 28 days of exposure to air, and 2000 abrasion cycles. This finding can be applied to the development of daily indoor and outdoor antifouling protective coatings and provides a new method for the preparation of green and durable superhydrophobic antifouling coating films.

Synthesis and performance evaluation of temperature and salt-resistant organic/inorganic composite copolymers

ABSTRACT Ordinary polymers have poor adaptability in high-temperature and high-salt reservoir environments due to their properties. Organic/inorganic composite copolymer microspheres have the advantages of both of them, which are expected to break through their applicability limitations in such oil reservoirs. Therefore, its preparation and performance have always been of great concern to researchers. In this paper, AM/AMPS/Si-St ternary copolymers were synthesized by precipitation polymerization; then modified nano-silica particles were added to synthesize AM/AMPS/Si-St/g-SiO2 organic/inorganic composite quaternary copolymers. FT-IR and SEM characterized the copolymers to confirm that they were prepared successfully. Experiments were carried out to investigate the concentration and ratio of monomers, which showed that the Weissenberg effect could be avoided. The number of polymer molecules could be stabilized under AM concentration of 12 wt%, AM/AMPS/Si-St ratio of 8:1:1, nano silica of 3.3% and the modification conditions of KH570:SiO2 = 1:1. The experiments of temperature and salt resistance of two copolymers were evaluated and compared were conducted by using viscosity and particle size as parameters. The results showed that quaternary copolymers could increase the viscosity retention rate by about 10% compared with ternary copolymers under high content of Na+ and Mg2+. When the two copolymers were placed at 150°C, the appearance and morphology of the terpolymer changed obviously. Through the SEM image of the quaternary copolymers, it could be seen that although the spherical shape of the microsphere had been gradually lost, no degradation occurred, and the stable time of the modified microspheres had been effectively extended.

Transparent superhydrophobic coating for copper metal and study of surface morphology and antimicrobial characteristics

Nowadays, copper is a widely used metal worldwide for various applications such as electronic materials, electrical circuits, ornamentals and decorative applications. Copper is widely known for its antimicrobial properties. Despite this fact, it is found to be susceptible to biocorrosion. To protect the copper metal from biocorrosion, hydrophobically modified silica nanoparticles were prepared by the sol gel process. The Prepared sol solution was characterized by Particle size analysis, transmission electron microscopy (TEM) and infrared spectroscopy. Modified silica nanoparticles coated on the copper substrate to obtain superhydrophobic surface. Surface morphology was observed by scanning electron microscopy (SEM), electron dispersive microscopy (EDX) and atomic force microscopy analysis (AFM). Wettability and antimicrobial activity of the copper surface were also studied. The average particle size was found to be 96 nm and the formation of silica nanoparticle in the sol was also confirmed by IR spectra. The Contact angle of coated copper was found 163.3˚compared to 66.6˚ of uncoated copper surface which confirms the superhydrophobic behavior of the coated surface. The presence of nanostructured surfaces was responsible for superhydrophobic behavior which was confirmed by SEM and AFM studies. The coated copper showed excellent antimicrobial characteristics against E-coli.