Surface Modification Method Research Articles

Improved performance of the ultrafiltration membranes by simple modification with air plasma treatment and polymeric deposition

AbstractThis study seeks to increase the antifouling properties of fluorinated polyvinylidene (PVDF) membranes through the synergistic application of plasma treatment and polymer deposition, employing polymerizations of polyvinylpyrrolidone (PVP) and polyethyleneimine (PEI). The results show remarkable success in modifications, presenting exceptional performance. Two distinct surface modification methods, plasma treatment and polymer deposition, were used to improve the antifouling properties and filtration performance of PVDF membranes. The plasma used was a discharge dielectric barrier using ambient air as gas, and hydrophilic polymers, PVP, and PEI. The results outlined changes in membrane roughness with a significant roughness reduction of up to 43% evident based on topographic and morphological analyses. Hydraulic permeability analysis revealed a substantial 35‐fold increase, indicating a notable improvement in performance. All treated membranes exhibited higher water affinity and superior performance during 12‐h ultrafiltration compared to their untreated counterparts. After chemical cleaning, water flux recovery exceeded 85% for all treated membranes, indicating the inherent antifouling properties of the surface.

Silver Containing Antimicrobial Coatings on Innovative Ti-30Nb-5Mo β-Alloy Prepared by Micro-Arc Oxidation for Biomedical Implant Applications

Micro-arc oxidation (MAO) is a versatile surface-modification method that promotes higher wear and corrosion resistance, osseointegration, and biological activity to titanium alloys’ surfaces. This study aimed to modify the surface of a recently developed metastable β Ti alloy, which exhibits more favorable mechanical properties for implant applications compared to some commercial Ti alloys, by incorporating Ag into the coatings to introduce a bactericidal function to the surface. The Ti-30Nb-5Mo alloy, with lower elastic modulus, was treated by the MAO method using electrolyte solutions containing calcium acetate, magnesium acetate, β-glycerol phosphate, and varied concentrations of silver nitrate (1.5 mM, 2.5 mM, and 3.5 mM). With an increase in the concentration of silver ions in the electrolyte, the galvanostatic period during the MAO process decreased from 1.7 s to 0.5 s. The Ca/P ratio increased from 0.72 up to 1.36. X-ray diffraction showed that the MAO coatings were formed by rutile and anatase TiO2 main phases and calcium phosphates. X-ray photoelectron spectroscopy analysis detected the presence of amorphous Nb2O5, CaCO3, and MgCO3, and metallic and oxide forms of Ag. The increase in Ag in the electrolyte decreased the coating thickness (from 14.2 μm down to 10.0 μm), increased the contact angle (from 37.6° up to 57.4°), and slightly increased roughness (from 0.64 μm up to 0.79 μm). The maximum inhibition of Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans strains growth was of 43%, 43%, and 61%, respectively. The Ag did not negatively affect the differentiation of adipose-tissue-derived mesenchymal stem cells. Therefore, the treatment of the surface of the innovative Ti-30Nb-5Mo alloy by the MAO method was effective in producing a noncytotoxic porous coating with bactericidal properties and improved osseointegration capabilities.

Research on noise reduction of drive axle hypoid gear based on tooth surface mismatch modification

In order to reduce the transmission noise of drive axle hypoid gear, a method of tooth surface mismatch modification was proposed. Firstly, on the basis of establishing the grinding mathematical model of hypoid gear with cutter tilt, the theoretical tooth surface equation was derived, and the numerical tooth surface was calculated by dividing the grid points on tooth surface. Secondly, the pinion tooth surface which was full conjugated with gear tooth surface was constructed, and the tooth surface mismatch topography was established and decomposed into the first order and second order mismatch coefficients. According to the modification requirements, the pinion target surface was constructed by modifying the tooth surface mismatch coefficients, and the pinion modified machine setting parameters were acquired by establishing the pinion processing parameters corrected mathematical model. Finally, the loaded tooth contact analysis with finite element simulation and drive axle NVH (Noise, Vibration, Harshness) simulation were carried out for a pair of hypoid gear, therefore the loaded tooth contact areas, transmission errors curves, and noise simulation curves were obtained, and the simulation results show that after modification the tooth contact stress, loaded transmission errors amplitude, and NVH simulation curves value are all reduced. The road test results indicate that the drive axle hypoid gear howling phenomenon under the high speed operation can be eliminated, so the effectiveness of tooth surface modification method and NVH simulation method were verified.

Pengembangan Acetylated Cellulose Nanofibers dari Microcrystalline Cellulose: Studi Perubahan Gugus Fungsi dan Indeks Kristalinitas melalui Asetilasi dan Nanofibrilasi

Cellulose nanofiber (CNF) has promising potential as a reinforcement in polymer matrix nanocomposites. CNF is polar or hydrophilic due to having many hydroxyl groups. When CNF particles are combined with a non-polar polymer matrix, the CNF is difficult to distribute evenly and tends to agglomerate due to differences in polarity so that the strengthening effect of CNF is limited. To overcome this problem, it is necessary to chemically modify the CNF surface. Acetylation is one of the most widely used CNF surface modification methods to increase the compatibility between a non-polar polymer matrix and CNF. Through the acetylation process, some of the hydroxyl groups of CNF are replaced with acetyl groups which are hydrophobic. Furthermore, the CNF resulting from the acetylation process is known as acetylated CNF (acetylated cellulose nanofibers or ACNF). The acetylation process is carried out by first mixing microcrystalline cellulose (MCC) particles into 75 mL of acetic anhydride solution. Next, the mixture was stirred using a high-speed blender for 30 minutes for the MCC nanofibrillation process to occur. In this research, the influence of acetylation and nanofibrillation processes on the characteristics of ACNF was studied through studying chemical structure changes using ATR-FTIR and crystallinity index using XRD. The results of the ATR-FTIR analysis show that there are 3 new peaks in the ACNF spectrum, namely at 1720, 1369 and 1203 cm-1, which proves that there is a change in the structure of cellulose after being given acetylation treatment. The results of XRD show that surface treatment of acetylation and nanofibrillation with a high-speed blender increases the ACNF crystallinity index value by 82.53%. Overall, the resulting ACNF has great potential as a reinforcement for polymer matrix nanocomposites.

Surface-mediated self-assembly of click-reactive cello-oligosaccharides for fabricating functional nonwoven fabrics

ABSTRACT Polymer fabrics are versatile materials used in various fields. Surface modification methods for hydrophobic polymer fibers have been developed to endow the materials with water wettability and functionality. Nevertheless, it remains a challenge to freely introduce functional groups to polymer fiber surfaces in a simple manner. Herein, we report the decoration of nonwoven fabric surfaces with azidated cello-oligosaccharide assemblies via molecular self-assembly. Cello-oligosaccharides with a terminal azido group were enzymatically synthesized and allowed to self-assemble in polyolefin, polyester, and vinylon nonwoven fabrics. It was found that the functional oligosaccharides formed bark-like assemblies on the nonwoven fiber surfaces, probably through heterogeneous nucleation. The hydrophilic oligosaccharide assemblies made the hydrophobic nonwoven surfaces water-wettable. Moreover, the azido group at oligosaccharide terminal was available for the post-functionalization of the modified nonwovens. In fact, an antigen was successfully conjugated to the modified nonwovens via the click chemistry. The antigen-conjugated nonwovens were useful for the specific and quantitative detection of a corresponding antibody. Our findings demonstrate the great potential of cello-oligosaccharide assembly for the functionalization of fabrics and other polymeric materials.

Enhanced Photocatalysis of Electrically Polarized Titania Nanosheets.

Titania (TiO2) nanosheets are crystals with controlled, highly ordered structures that improve the functionality of conventional TiO2 nanoparticles. Various surface modification methods have been studied to enhance the effectiveness of these materials as photocatalysts. Surface modifications using electrical polarization have attracted considerable attention in recent years because they can improve the function of titania without changing its composition. However, the combination of facet engineering and electrical polarization has not been shown to improve the functionality of TiO2 nanosheets. In the present study, the dye-degradation performance of polarized TiO2 nanosheets was evaluated. TiO2 nanosheets with a F/Ti ratio of 0.3 were synthesized via a hydrothermal method. The crystal morphology and structure were evaluated using transmission electron microscopy and X-ray diffraction. Then, electrical polarization was performed under a DC electric field of 300 V at 300 °C. The polarized material was evaluated using thermally stimulated current measurements. A dye-degradation assay was performed using a methylene blue solution under ultraviolet irradiation. The polarized TiO2 nanosheets exhibited a dense surface charge and accelerated decolorization. These results indicate that electrical polarization can be used to enhance the photocatalytic activity of TiO2.

A novel copper surface modification approach based on pinless friction stir surface processing technique with ultra-low heat input

Improving the wear and corrosion performances of widely employed copper and its alloy components can effectively extend their service life. In this study, a novel copper surface modification method based on the friction stir surface processing (FSSP) technique was achieved. Subject to FSSP with pinless tool and low heat-input process parameters (including a minimal axis tilt and extremely low rotational speed), the modified copper surface exhibited enhancement rates of 34.25 % in hardness and 44.76 % in tensile strength, and improved high wear and corrosion resistance characteristics. The research suggests that the primary reasons for the enhanced surface properties are the grain refinement strengthening effect and the rapid formation of a passive film. Additionally, the ultra-low heat input resulted in the preservation of numerous dislocation tangles and incomplete dynamic recrystallization in the modified region, which represented a microstructural evolution mechanism distinct from the traditional friction stir processing. This work provides a reference for a low-energy-consumption and easily achievable approach for enhancing the surface properties of metals.

Investigations on friction stir composite processing and picosecond laser-induced surface modification on mechanical properties of β-titanium alloy

This work introduced a new surface modification method of titanium alloy Ti-35Nb-2Ta-3Zr alloy by friction stir machining (FSP) and picosecond laser-induced surface modification (PsLSM). The results show that the properties of the alloy are the best when the picosecond laser scanning speed is 50 mm/s, the laser power is 0.5 W. Compared with the untreated, the microhardness is increased by 68.7%, Young's modulus is reduced by 40%, the friction coefficient is reduced by 81.8%, and the friction loss is reduced by 62.5%. Among them, the experimental results show that the effect of PsLSM on performance improvement is higher than that of FSP, but the performance of samples treated with FSP+PsLSM is higher than that of samples treated with PsLSM. It was found that the LIPSS formed on the sample's surface after PsLSM treatment is the main reason for the improvement of mechanical properties, and the ultra-high temperature remelting effect of FSP treatment makes the surface grains refined. This study provides a new idea and method for surface modification of β titanium alloy to improve its mechanical properties.

A feasible way to modify microcrystalline cellulose powder and its reinforcing effect for NBR composites

AbstractIt has attracted tremendous attention for replacing petroleum‐based carbon black or mineral fillers with renewable, biology‐based and low‐cost cellulose. However, the reinforcing effect of cellulose, especially at the microscale, is still a great challenge in the polymer industry. In this work, a feasible surface modification method for microcrystalline cellulose powder (MCC) in all solid states is proposed by using rubber accelerators N‐cyclohexyl benzothiazole‐2‐sulphenamidee (CBS) and 2,2′‐dibenzothiazoledisulfide (DM). These accelerators not only accelerate the sulfur crosslink of nitrile butadiene rubber (NBR), but also graft to rubber molecular chains and form hydrogen bonds with MCC, resulting in good interfacial interaction and good dispersion of MCC in the NBR matrix. As a consequence, the tensile strength and elongation at break of NBR/10MCC reach up to 20.12 MPa and 511%, respectively, which are the highest values of NBR/MCC or cellulose nanocrystals (CNCs) composites we can find in the world and are comparable to those of carbon black or mineral fillers. This provides a more effective and environmentally friendly way of using MCC or CNCs in the polymer industry.Highlights Microcrystalline cellulose powder can reinforce NBR. Hydrogen bonds have been established between accelerators and MCC. The tensile strength of NBR/10MCC composite reaches 20 MPa. The reinforcing mechanism is ascribed to the immobilized rubber layer.

Study on the adsorption performance of modified high silica fly ash for methylene blue.

Presently, there are several issues associated with solid waste fly ash, such as its accumulation and storage, low comprehensive utilization rate, lack of high-value utilization technology, environmental risk and ecological impact. Thus, based on the high silica content and adsorption characteristics of fly ash, two novel adsorbents, namely mesoporous silica-based material (MSM) and sodium dodecyl sulfate-modified fly ash (SDS-FA), were prepared using an ultrasound-assisted alkali fusion-hydrothermal method and surface modification method. Furthermore, effects of adsorbent dosage, initial pH, contact time, and initial concentration of the solution on the adsorption of the organic pollutant methylene blue (MB) by fly ash, MSM, and SDS-FA were investigated to select the optimal modified high silica fly ash adsorbent. Based on the adsorption isotherms and adsorption kinetics, together with SEM, XRD, FTIR and BET analyses, the adsorption mechanism of MSM for MB was revealed. The results showed that under the conditions of an adsorbent dosage of 2 g L-1, initial pH of 9, contact time of 150 min, and initial concentration of 100 mg L-1, MSM and SDS-FA exhibited removal efficiencies of 92.69% and 84.64% for MB, respectively, which were significantly higher than that of fly ash alone. The adsorption of MB by MSM and SDS-FA followed the Langmuir model and pseudo-second-order kinetics, indicating monolayer adsorption with chemical adsorption as the dominant mechanism. The mechanism of the adsorption of MB by MSM is mainly the result of the synergistic effect among its increased specific surface area, hydrogen bonding, ion exchange, and electrostatic interactions. After five cycles of adsorption-desorption process, the removal efficiency of MSM for MB consistently remained above 80%. Therefore, MSM can serve as a valuable reference for the resource utilization of fly ash and remediation of dye-polluted wastewater.

Synthesis and physicochemical properties of visible-light-excited carbon dots: impact of sugar ring structure and surface chemistry

We aimed to enhance the fluorescence quantum yield of sugar-derived carbon dots along with tuning the excitation wavelength to the visible region via a surface modification method with simple acids.

Recent progress in eutectic gallium indium (EGaIn): surface modification and applications

EGaIn plays an important role in flexible electronics, this paper focuses on a review of the key factors affecting the surface tension of liquid metals and surface modification methods and applications.

Nanopore sensing specific enhancement technique for single molecule detection

Nanopore sensors have become important tools for analyzing biomarkers, including but not limited to nucleic acids, proteins, and other biomolecules that play important roles in life. Though the nanopores themselves have no selectivity towards target molecules, higher sensitivity of nanopore sensing to the target biomarkers could be achieved with the help of the specificity enhancement technology. In this work, the basic principles of nanopore sensing are first introduced, then methods of modifying nanopore surface as well as the development and application of those selectivity enhancement technologies of nanopore sensing in recent years are reviewed. These enhancement technologies primarily fall into two categories: surface functionalization and molecular probes. Surface functionalization is further categorized based on the types of functional molecules used, while molecular probes are classified according to carrier forms. Finally, in this paper several challenges that nanopore sensing continues to encounter are discussed and some suggestions are made for its future development.

Increasing the adhesion laminated films based on polyimide to the surface

Polyimide film is widely used in various fields of industry, ranging from space technology to microelectronics. The widespread use of the film is due to its high thermal stability, low dielectric constant and good mechanical strength. However, the polyimide film also has a serious disadvantage that prevents its use in a number of applications, namely, a relatively low surface energy, manifested in the low adhesive strength of the film’s compounds with other polymers and metals. Currently, a number of surface modification methods of polyimide film are known to improve adhesive properties of the surface without changing the properties of material thickness. The existing methods of polyimide film surface modification can be divided into two large groups: chemical, “wet” methods and “dry” ion-beam and plasma methods. The article presents the results of studies of polyimide adhesion changes depending on the methods of plasma treatment.

Surface modification of carbon nanotubes and their nanocomposites for fuel cell applications: A review

<abstract> <p>Carbon nanotubes (CNTs) have drawn great attention as potential materials for energy conversion and storage systems such as batteries, supercapacitors, and fuel cells. Among these energy conversion and storage systems, the fuel cells had stood out owing to their high-power density, energy conversion efficiency and zero greenhouse gasses emission. In fuel cells, CNTs have been widely studied as catalyst support, bipolar plates and electrode material due to their outstanding mechanical strength, chemical stability, electrical and thermal conductivity, and high specific surface area. The use of CNT has been shown to enhance the electrocatalytic performance of the catalyst, corrosion resistivity, improve the transmission performance of the fuel cell and reduce the cost of fuel cells. The use of CNTs in fuel cells has drastically reduced the use of noble metals. However, the major drawback to the utilization of pristine CNTs in fuel cells are; poor dispersion, agglomeration, and insolubility of CNTs in most solvents. Surface engineering of CNTs and CNT nanocomposites has proven to remarkably remedy these challenges and significantly enhanced the electrochemical performance of fuel cells. This review discusses the different methods of surface modification of CNTs and their nanocomposite utilized in fuel cell applications. The effect of CNTs in improving the performance of fuel cell catalyst, membrane electrode assembly and bipolar plates of fuel cells. The interaction between the CNTs catalyst support and the catalyst is also reviewed. Lastly, the authors outlined the challenges and recommendations for future study of surface functionalized CNTs composite for fuel cell application.</p> </abstract>

Construction of a layer-by-layer self-assembled rosemarinic acid delivery system on the surface of CFRPEEK implants for enhanced anti-inflammatory and osseointegration activities.

Carbon fiber-reinforced polyether ether ketone (CFRPEEK) implants have attracted widespread attention in the field of clinical bone defect repair. However, the surface bioinertness confines the application of CFRPEEK implants. Inspired by the study of rosmarinic acid (RA)-promoted osteogenic differentiation, a self-assembly surface modification method based on electrostatic interactions, involving deposition of sodium carboxymethyl cellulose/chitosan and rosmarinic acid layer by layer on the surface of poly-L-lysine modified hydroxy CFRPEEK (SCPP/CC5@RA), is proposed to introduce RA on the surface of CFRPEEK for bioactivation. After layer-by-layer self-assembly (LBL), the surface of SCPP/CC5@RA exhibits weak electrophoresis (11.43 eV), suitable hydrophilicity, and bioactivity. The results of in vitro studies indicate that the RA release behavior of SCPP/CC5@RA effectively regulates the immune-inflammatory response and promotes the differentiation of osteoblasts. The rapid release of RA (0.17 μg mL-1) in the initial stage can downregulate the secretion of inflammation-related cytokines and significantly reduce oxidative stress levels; the sustained release of RA (0.06 μg mL-1) in the late stage can upregulate the expression of osteogenesis-related genes and induce mineralization of osteoblasts. Moreover, the rabbit tibia defect model demonstrates that the LBL technique can enhance the osseointegration of CFRPEEK implants. Compared with the control group, the bone trabecular thickness of the SCPP/CC5@RA group increases by 1.36 times, and the maximum pushing force increases by 2.67 times. In summary, this study provides a promising LBL based RA delivery system for the development of a dual-functional CFRPEEK implant in the field of bone implant biomaterials.

Formation of oxygen protective layer on monolayer MoS2 via low energy electron irradiation.

Monolayer molybdenum disulfide (MoS2) semiconductors are the new generation of two-dimensional materials that possess several advantages compared to graphene due to their tunable bandgap and high electron mobility. Several approaches have been used to modify their physical properties for optical device applications. Here, we report a facile and non-destructive surface modification method for monolayer MoS2 via electron irradiation at a low, 5 kV accelerating voltage. After electron irradiation, the results of Raman and photoluminescence spectroscopy confirmed that the structure remains unchanged. However, when the modified surface was illuminated with a 532 nm laser for a prolonged period, the PL intensity was quenched as a result of oxygen desorption. Interestingly, the PL intensity can be recovered when left in ambient conditions for 10 h. The analysis of the PL spectrum revealed a decrease of trion, which is consistent with the readsorbed O2 molecules on the surface that deplete electrons and lead to PL recovery. We attribute this effect to the enhancement of the n-type character of monolayer MoS2 after electron irradiation. The sensitive nature of the modified surface to oxygen suggests that this approach may be used as a tool for the fabrication of MoS2 oxygen sensors.

Properties of biodegradable polymer coatings with hydroxyapatite on a titanium alloy substrate.

Purpose: Titanium alloys are among the most widely used materials in medicine, especially in orthopedics. However, their use requires the application of an appropriate surface modification method to improve their properties. Such methods include anodic oxidation and the application of polymer coatings, which limit the release of alloying element ions. In addition, biodegradable polymer coatings can serve as a carrier for drugs and other substances. The paper presents the results of research on the physical properties of biodegradable polymer coatings containing nanoparticle hydroxyapatite on a titanium alloy substrate. Methods: A PLGA coating was used in the tests. The coatings on the substrate of the anodized Ti6Al7Nb alloy were applied by ultrasonic spray coating. The tests were carried out for coatings with various hydroxyapatite content (5, 10, 15, 20%) and thickness resulting from the number of layers applied (5, 10, 15 layers). The scope of the research included microscopic observations using scanning electron microscopy, topography tests with optical profilometry, structural studies using X-ray diffraction, as well as wettability and adhesion tests. Results: The results shows that with the use of ultrasonic spray coating system is possible to obtain the continuous coatings containing hydroxyapaptite. Conclusions: The properties of the coating can be controlled by changing the percentage of hydroxyapatite and the number of layers of which the coating is composed.

Application of advanced surface modification techniques in titanium-based implants: latest strategies for enhanced antibacterial properties and osseointegration.

Titanium-based implants, renowned for their excellent mechanical properties, corrosion resistance, and biocompatibility, have found widespread application as premier implant materials in the medical field. However, as bioinert materials, they often face challenges such as implant failure caused by bacterial infections and inadequate osseointegration post-implantation. Thus, to address these issues, researchers have developed various surface modification techniques to enhance the surface properties and bioactivity of titanium-based implants. This review aims to outline several key surface modification methods for titanium-based implants, including acid etching, sol-gel method, chemical vapor deposition, electrochemical techniques, layer-by-layer self-assembly, and chemical grafting. It briefly summarizes the advantages, limitations, and potential applications of these technologies, presenting readers with a comprehensive perspective on the latest advances and trends in the surface modification of titanium-based implants.

Carbon quantum dots (CQDs)-modified polymers: a review of non-optical applications.

Carbon quantum dots (CQDs) are a promising candidate to replace metal-based additives for polymer reinforcement and functionalization. Specifically, vast interest in CQDs for polymer functionalization stems from their cost effectiveness, sustainable organic precursors, and their non-toxicity. Although several reviews of optical devices based on CQDs have been reported, this mini-review covers the non-optical aspects of CQD-polymer composites. Applications of CQD-modified polymers for smart devices, mechanical reinforcement, textile surface-modification methods, membranes, protective coatings, and thermal resistance are summarized. The synthesis method of CQDs, their dispersion in a polymer matrix and the underlying mechanisms related to the enhanced performance of composites are outlined. Unlike nano-reinforcements, CQDs are self-stabilized and offer an extremely high surface area, which significantly alters the polymer properties at a 1-2% concentration. Finally, a comparative analysis of recent advances in CQD-polymer composites, their problems, and future directions are discussed.