Organic Molybdenum Research Articles

Modulation of animal and plant tissue growth with collagen‐starch‐organic molybdenum networks hydrogel biomatrices

AbstractThe development of hydrogel biomatrices with potential to modulate animal and plant tissue growth is ongoing. In this study, molybdenum bio‐metal–organic frameworks (MOFs) (Mo‐bioMOFs) incorporating essential amino acids such as l‐histidine (Mo‐His), l‐phenylalanine (Mo‐Phe), and l‐tryptophan (Mo‐Trp) were encapsulated in semi‐interpenetrating polymer network (semi‐IPN) hydrogels composed of collagen and starch. The structure and properties of these materials show dependence on the amino acid that constitutes the Mo‐bioMOFs. The biomatrices have a semi‐crystalline surface with increased porosity when using Mo‐His; this system also benefits swelling. Increased crosslinking, acceleration in gelation, and mechanical improvement are observed for the system based on Mo‐Phe. Methylene blue release experiments were conducted, demonstrating that matrices including Mo‐bioMOFs exhibit controlled release profiles, indicating highly stable retention of Mo‐bioMOFs in the semi‐IPN matrix. The biomatrices enhance the metabolism and proliferation of fibroblasts and monocytes, with Mo‐Trp reducing the secretion of inflammatory cytokines like TNF‐α. The biomatrices exhibit gradual and slow mass loss when exposed to collagenase and commercial vegetable substrates. Both leaf and root cells of tomato plants (Solanum lycopersicum) show increased metabolism and growth when exposed to Mo‐Phe and Mo‐His. Notably, the biomatrix containing Mo‐Phe promotes the most substantial plant growth and foliage after 30 days. These biomatrices have potential applications in chronic wound healing and agriculture.

Molecular Structures, Tribological Properties, and Working Mechanisms of Sulfur- and Phosphorus-Free Organic Molybdenum as Additives in Lubricants: A Short Review

Abstract Traditional oil-soluble organic molybdenum (OM) as friction modifiers (FMs) in engine oils contain sulfur and/or phosphorus. Both sulfur and phosphorus are detrimental to the automotive exhaust gas catalysts. Consequently, sulfur and phosphorus in commercial engine oils are limited seriously by laws. Recently, oil-soluble sulfur- and phosphorus-free organic molybdenum (SPFMo) has been developed and measured intensively. This article reviews the molecular structures, tribological properties, and working mechanisms of SPFMo as FM in oils. Some bottlenecks that constrain the wide applications of SPFMo in engine oils are also summarized. In addition, some routes for overcoming the bottlenecks are suggested. Finally, some potential developments of SPFMo in the future are proposed. This review will provide a comprehensive understanding of SPFMo to the researchers in the field of oil additives.

Synergistic lubrication effect of OLC and MoDTC for reducing friction and wear of MAO ceramic coating on TC4 alloy

AbstractTC4 titanium alloy has been widely used in the automotive field due to its exceptional properties. However, inherent defects such as low hardness and poor wear resistance for TC4 alloy limited its wider application. The microarc oxidation (MAO) technique was employed in this paper to prepare MAO coatings on TC4 titanium alloy. The microstructure, phase structure, mechanical properties, and tribological performance were systematically evaluated. The results show that the coating contains a large amount of rutile TiO2 hard phase after MAO treatment, which significantly improves the mechanical properties of the substrate. The hardness of the MAO coating can reach 581 HV.05. Furthermore, the synergistic lubrication effect of onion‐like carbon (OLC) nanoparticles and organic molybdenum dithiocarbamate (MoDTC) in PAO oil was observed for MAO‐treated TC4. Particularly, when .01 wt.% OLC is used with 1 wt.% MoDTC oil, the coefficient of friction (COF) decreases to .062, and the wear rate decreases to 4.3 × 10−7 mm3/Nm. Combined Raman and X‐ray photoelectron spectroscopy (XPS) analysis indicate that OLC is deposited on coating area to form a lubricating carbon film. Additionally, OLC can promote the decomposition of MoDTC during sliding to generate a tribofilm containing MoS2.

Oil-soluble sulfur-containing organic molybdenum (SOM) as lubricant additives: a review

Abstract In situ formation of lamellar MoS2 nanomaterials between the tribocontacts during frictions through adding oil-soluble sulfur-containing organic molybdenum (SOM) additives into lubricating oils is an alternative route of dispersing pre-formed MoS2 into lubricants directly, which is difficult to disperse homogeneously in oils. In this technology, the synthesis of SOM with appropriate S and Mo contents and successful generation of enough MoS2 during friction by adjusted working conditions are two crucial factors determining the efficiency of SOM on the friction-reduction and anti-wear behaviors of the SOM-containing oils. Given the fact that SOM additives have been used intensively in both laboratory researches and engineering applications, this review discusses in detail the molecular structures, tribological behaviors, compatibility and synergistic effects with the other additives, and some application bottlenecks of the reported SOM compounds that may constrain their wide applications as lubricant additives. Moreover, some routes for overcoming these application bottlenecks are suggested. This review also concludes the basic mechanisms for the lubrication capabilities of the SOM and provides some suggestions for utilizing SOM additives in advanced lubrication systems. Finally, the future development of SOM as oil additives is proposed and summarized.

The synthesis and tribological behaviour of a phosphorus-free triazine organic molybdenum as friction modifier

A phosphorus-free triazine-based organic molybdenum compound (DCDM) was designed and synthesized by using the click chemistry approach, and its friction-reducing and anti-wear properties were evaluated in PAO10 base oil. The results indicated that DCDM exhibited excellent tribological performance, with a reduction of approximately 35% in friction coefficient and about 46% in wear scar diameter, due to the synergy effect between Mo and S. Surface analysis by EDS and XPS revealed the formation of MoO3, Fe2(SO4)3, FeS, and MoS2 in the friction film. And it was furhter confirmed that the presence of MoS2 in the friction film contributed most significantly to the enhancement of the friction-reducing and anti-wear properties of the developed triazine-based organic molybdenum compound in PAO10 base oil.

In situ preparation of Cu-Mo-S nanoparticle additive with multi-functional tribological properties

Complex operating conditions pose greater challenges for lubricants, making the development of multi-functional additives a trend. This research introduces a multifunctional Cu-Mo-S nanoparticle (CMS) additive, synthesized using a unique one-pot in situ method. The CMS significantly improved the tribological performance and oxidation stability of base oils. Specifically, 0.5 wt% CMS manifested a remarkable reduction in the friction coefficient and wear volume of ester-based oils by 74.75% and 95.91%, accompanied by a noteworthy increase in the extreme pressure capabilities exceeding 50%, outperforming the individual copper nanoparticles, organic molybdenum, and their mixtures. The remarkable results are attributed to the distinctive structure of CMS, which decomposed during the friction process, forming a continuous friction film containing copper, molybdenum, and iron compounds.

Load-carrying capacity and tribomechanism of DDA/MADE modified MoO3 nanoparticle as an additive for alkylated naphthalene base oil

Metal oxide nanoparticles as lubricant additives have attracted much attention, thanks to their excellent anti-wear ability and load-carrying capacity. Unfortunately, organic molybdenum, a small molecule auxiliary of zinc dialkyldithiophosphate (ZDDP) with high reactivity, exhibits poor load-bearing capacity. Therefore, molybdenum oxide nanoparticle (denoted as MONP) was surface-capped by dodecylamine (DDA) and maleic anhydride dodecyl ester (MADE) to obtain DDA/MADE-MONP, an organic-inorganic nanohybrid as a potential replacement of sulfur- and phosphorus-free commercial organic molybdenum additive (Organic-Mo). The as-prepared DDA/MADE-MONP nanohybrid was characterized by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy; and its effect on the load-bearing capacity of an alkylated naphthalene base oil (AN30), as used alone and combined with ZDDP, was investigated. Results show that, whether used alone or combined with ZDDP, the as-prepared DDA/MADE-MONP has better load-bearing capacity than the commercial organic molybdenum additive. The reason lies in that DDA/MADE-MONP can release MoO3 nanocores during the friction process to fill up the pits on the worn steel surface and form a dense protective tribofilm.

Towards outstanding lubricity performance of proton-type ionic liquids or synergistic effects with friction modifiers used as oil additives at the steel/steel interface.

Anti-wear (AW) additives and friction modifiers (FMs) and their interactions in lubricants are critical to tribological performance. This research investigates the compatibility and synergism of three oil-soluble alkylamine-phosphate ionic liquids with friction modifiers, organomolybdenum compounds. Three proton-based ionic liquids (PILs) were synthesized using a simple, low-cost, and unadulterated procedure as well as the chain lengths of the PILs affected the effectiveness of friction reduction and anti-wear. For example, the effect of a short-chain PIL alone as an additive on friction and wear behavior was not significant, whereas a long-chain PIL was more effective. In addition, PILs appeared to be able to coexist with organic molybdenum compounds and worked synergistically with dialkyl dithiophosphate oxygen molybdenum (MoDDP) to produce a sustained low coefficient of boundary friction (the coefficient of friction approaching 0.042). We proposed a three-stage tribochemical process to explain this interaction of PILs + MoDDP with contact surfaces to form physically adsorbed friction-reducing films and chemically reactive wear-protective films. This study reveals the compatibility and synergistic effects of two common lubricant components, which can be used to guide lubricant development in the future.

Correction to: Voltage-Assisted Tribofilm Formation of Sulfur- and Phosphorus-Free Organic Molybdenum Additive on Bearing Steel Surfaces in Industrial Base Oils

Correction to: Voltage-Assisted Tribofilm Formation of Sulfur- and Phosphorus-Free Organic Molybdenum Additive on Bearing Steel Surfaces in Industrial Base Oils

Synergistic tribological effect between polyisobutylene succinimide-modified molybdenum oxide nanoparticle and zinc dialkyldithiophosphate for reducing friction and wear of diamond-like carbon coating under boundary lubrication

Organic molybdenum lubricant additive like molybdenum dialkyl dithiocarbamate (MoDTC) can cause wear acceleration of diamond-like carbon (DLC) coating coupled with steel under boundary lubrication, which hinders its industrial application. Therefore, polyisobutylene succinimide (PIBS), an organo molybdenum amide, was adopted to modify molybdenum oxide affording molybdenum polyisobutylene succinimide-molybdenum oxide nanoparticles (MPIBS-MONPs) with potential to prevent the wear acceleration of DLC coating. The thermal stability of MPIBS-MONPs was evaluated by thermogravimetric analysis. Their tribological properties as the additives in di-isooctyl sebacate (DIOS) were evaluated with MoDTC as a control; and their tribomechanism was investigated in relation to their tribochemical reactions and synergistic tribological effect with zinc dialkyldithiophosphate (ZDDP) as well as worn surface characterizations. Findings indicate that MPIBS-MONPs/ZDDP added in DIOS can significantly reduce the friction and wear of DLC coating, being much superior to MoDTC. This is because MPIBS-MONPs and ZDDP jointly take part in tribochemical reactions to form a composite tribofilm that can increase the wear resistance of DLC coating. Namely, the molybdenum amide on MPIBS-MONPs surface can react with ZDDP to form MoS2 film with excellent friction-reducing ability; and MPIBS-MONPs can release molybdenum oxide nanoparticle to form deposited lubrication layer on worn surfaces. The as-formed composite tribofilm consisting of molybdenum oxide nanocrystal, amorphous polyphosphate, and molybdenum disulfide as well as a small amount of Mo2C accounts for the increase in the wear resistance of DLC coating under boundary lubrication.

Tribological mechanisms of the synergistic effect between sulfur- and phosphorus-free organic molybdenum and ZDDP

In this work, three environmentally friendly sulfur- and phosphorus-free organic molybdenums, MODE (amide type), MGMO (ester type) and MGME (ether type) with different structures were prepared, and the relationship between molecular structure and tribological properties was investigated. Furthermore, the tribological properties and mechanisms after compounding with conventional zinc dialkyldithiophosphate (ZDDP) were also investigated, indicating that the synergistic effect on antiwear and antifriction properties has the following order: MODE+ZDDP > MGMO+ZDDP > MGME+ZDDP. We further explored the tribological mechanisms through the in-depth surface and cross-sectional analyses, which manifests that the formation of homogeneous and compact tribofilm composed of molybdenum disulfide, molybdenum oxide, sulfate, phosphate, and polyphosphate with the thickness of 50–200 nm is contributed to the excellent synergistic effect.

Producing p-Doped Surface for Hole Transporting Layer-Free Nonfullerene Organic Solar Cells.

Hole transporting layer-free organic solar cells with simplified device structures are desirable for their mass production. In this work, a p-dopant of organic molybdenum peroxide (OMP) to dope nonfullerene active layers to produce p-doped surface on the active layer is adopted. The OMP can effectively dope widely used polymer donors of nonfullerene organic solar cells, i.e., PTB7-Th, PBDB-T, and even PBDB-T-2F that has a very deep highest occupied molecular orbital (HOMO) energy level of -5.47eV. The doping mechanism lies in the strong oxidizing property of peroxide groups of the OMP leading to superior doping properties. In the end, hole transporting layer-free nonfullerene organic solar cells with the device structure of ITO/PEI-Zn/PBDB-T-2F:IT-4F/Ag are fabricated. The cells show a power conversion efficiency of 12.2% and good thermal stability.

Voltage-Assisted Tribofilm Formation of Sulfur- and Phosphorus-Free Organic Molybdenum Additive on Bearing Steel Surfaces in Industrial Base Oils

Voltage-Assisted Tribofilm Formation of Sulfur- and Phosphorus-Free Organic Molybdenum Additive on Bearing Steel Surfaces in Industrial Base Oils

Tribological performance of organic molybdenum in the presence of organic friction modifier.

The tribological performance of organic molybdenum in the present of organic friction modifier was investigated in this study. Three types of organic friction modifiers were selected, which are Glycerol monooleate, Pentaerythritol and N,N-Dimethylhexadecylamine. The organic molybdenum are MoDTC, MoDDP and molybdenum amide. Friction coefficient and wear were studied in block-on-ring test rig with steel test specimens. Experimental results indicate the Pentaerythritol shows synergistic effect with MoDTC in wide range temperature, while increased the friction coefficient of molybdenum amide in high temperature. N,N-Dimethylhexadecylamine shows synergistic effect with molybdenum amide, while hindered the friction reduction performance of MoDTC in low temperature. The presence of Glycerol monooleate reduced friction coefficient of MoDTC in low temperature, while increased the friction coefficient of molybdenum amide in most situations. All the tested organic friction modifiers improved the friction reduction performance of MoDDP. Most of the tested organic friction modifiers reduced the wear of organic molybdenum. The PT shows the best anti-wear performance with MoDTC. The tribo-chemical products in test specimens lubricated with different lubricant formulas indicate that the presences of Pentaerythritol promotes the production of MoS2 in MoDTC. N,N-Dimethylhexadecylamine promotes the production of MoS2 in molybdenum amide. The side products of MoO1.6S1.6 and Cr/MoS2 of MoDDP in high temperature lead to high friction coefficient.

Tribological behavior of a novel organic molybdenum containing dimercaptothiadiazole as a multifunctional additive in biodegradable base oil

Organic molybdenum friction modifier is an indispensable lubricating material owing to its remarkable tribological behavior, which has been widely used in various fields. Here, a feasible method is provided for the synthesis of thiadiazole organic molybdenum as a multifunctional lubricant additive in the trimethylolpropane trioleate biodegradable base oil. Results show that the coefficient of friction and the wear scar diameter are significantly decreased by ~39% and ~42%, respectively. Moreover, its extreme pressure performance is also improved by more than 50%. The XANES results show that the functional group of the thiadiazole and molybdate in the additive molecule will form a tribofilm rich in sulfate and molybdate to enhance the properties of friction-reducing, anti-wear and load-bearing capacity of the based oil.

Tribological behavior of a novel organic molybdenum containing mercaptotriazine as a multifunctional environmentally friendly additive

In this study, we developed a new multifunctional mercaptotriazine-containing organic molybdenum with excellent properties to enhance the tribological performance of biodegradable based oils. The coefficient of friction and wear scar diameter are greatly reduced up to ~40% and ~44%, respectively. Surface analyses reveal that the tribofilm is mainly composed of FeS, FeSO4, Fe2O3, MoO3, MoS2 and FeMoO4. Furthermore, the tribofilm also exhibits a layered structure with different chemical compositions, in which the sulfur in the body tribofilm mainly exists in the form of S2−, SO32− and SO42−, while the sulfur in the subsurface of the tribofilm is mainly composed of S2− and SO42−. Our findings might pave the way for exploiting the multifunctional and environmentally-friendly lubricating materials.

Nanocomposite of ultra-small MoO2 embedded in nitrogen-doped carbon: In situ derivation from an organic molybdenum complex and its superior Li-Ion storage performance

MoO2 is a promising anode material for lithium-ion batteries, however, the lithiation of bulk MoO2 is usually limited to addition-type reaction at room temperature, and the conversion reaction is hindered because of the sluggish kinetics. Herein, a nanocomposite of MoO2 embedded in nitrogen-doped carbon (MoO2/NC) is synthesized through the in situ thermolysis of an organic molybdenum complex MoO2(acac)(phen) (acac = acetylacetone, phen = 1,10-Phenanthroline). Owing to the fact that [MoO2]2+ can be strongly chelated by phen, the molybdenum source in the MoO2(acac)(phen) precursor is highly dispersed, leading to the formation of ultra-small MoO2 nanoparticles in the nanocomposite, which can facilitate the conversion reaction. Moreover, the NC matrix can guarantee a high electrical conductivity and effectively accommodate the volume changes triggered by the conversion reaction. Consequently, the MoO2/NC nanocomposite exhibits outstanding electrochemical properties, including large reversible capacity of 950 mA h g−1 at 0.1 A g−1, high-rate capability of 605 mA h g−1 at 2 A g−1, and excellent cycling stability over 500 cycles as an anode material for lithium-ion batteries.

Tribological properties of novel palygorskite nanoplatelets used as oil-based lubricant additives

Layered palygorskite (PAL), commonly called attapulgite, is a natural inorganic clay mineral composed of magnesium silicate. In this study, an aqueous miscible organic solvent treatment method is adopted to prepare molybdenum-dotted palygorskite (Amo-PMo) nanoplatelets, which greatly improved the specific surface area of PAL and the dispersion effect in an oil-based lubricant system. Their layered structure and size were confirmed using transmission electron microscopy (TEM) and atomic force microscopy. Following a tribological test lubricated with three additives (PAL, organic molybdenum (SN-Mo), and Amo-PMo), it was found that the sample of 0.5 wt% Amo-PMo exhibited the best tribological properties with a coefficient of friction of 0.09. Moreover, the resulting wear scar diameter and wear volume of the sliding ball surface were 63% and 49.6% of those lubricated with base oil, respectively. Its excellent lubricating performance and self-repairing ability were mainly attributed to the generated MoS2 adsorbed on the contact surfaces during the tribochemical reaction, thereby effectively preventing the direct collision between asperities on sliding solid surfaces. Thus, as-prepared Amo-PMo nanoplatelets show great potential as oil-based lubricant additives, and this study enriches the existing application of PAL in industry.

Preparation and tribological behaviour of poly(methyl methacrylate) (PMMA) microcapsules containing friction modifiers

Aims: Microcapsules comprising of a poly(methyl methacrylate) (PMMA) shell and friction modifier (FM) core were prepared to reduce the friction and extend the service life of engine lubricating oil.Methods: Microcapsules containing both organic FM and molybdenum FM were produced via solvent evaporation technique. The friction coefficient, thermal stability, and chemical composition of microcapsules were investigated.Results: The incorporation of microcapsules in lubricating oil dramatically reduced the friction coefficient to be lower than that of virgin FM. Organic FM and molybdenum FM are compatible during the encapsulation process. The release of the FM inside the microcapsules was controllable by thermal degradation of polymeric shell at 150 °C or mechanical rupture at room temperature.Conclusions: This study provided a novel approach to improve the tribological properties of lubricating oil with long service life, facile fabrication and low cost and will find potential applications in lubrication industry for internal combustion engines.

Effect of Organic-Mo on the Wear Behavior of Phenolic Resin Composites

Organic molybdenum (e.g., molybdenum dialkyldithiocarbamate, Mo-DTC) is a typical additive for liquid lubricants which can produce a significant anti-wear role with only a minor addition. In this article Mo-DTC additives were used to enhance the wear resistance of a phenolic resin. Phenolic/Mo-DTC composites with various Mo-DTC filler ratios were prepared by hot-press molding. The hardness and wear performance of the composites were measured by a Shore durometer and by an M-2000 friction and wear tester, respectively. The results showed that after adding the Mo-DTC filler, both the hardness and the anti-wear properties of the composites materials were improved. Under the condition of high-speed with a smooth ring, the wear scar length for the sample with 1% Mo-DTC content decreased by 45.6% compared with that of the neat phenolic resin whereas for a wire rope ring a decrease of 16% was observed for 0.5% Mo-DTC. Based on the wear morphology of the composites, the wear mechanisms of the designed phenolic/Mo-DTC composites were determined.