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The design and development of functional hybrid nanomaterials is currently a topic of great interest in biomedicine. Herein we investigated the grafting of Ru(II) polypyridyl complexes onto gold nanospheres (Ru@AuNPs) to improve the particles' near infrared (NIR) absorption, and ultimately allow for application in photothermal cancer therapy. As demonstrated in this article, these ruthenium(II) complexes could indeed significantly enhance gold nanospheres' two-photon luminescence (PTL) intensity and photothermal therapy (PTT) efficiency. The best dual functional nanoparticles of this study were successfully used for real-time luminescent imaging-guided PTT in live cancer cells. Furthermore, in vivo tumor ablation was achieved with excellent treatment efficacy under a diode laser (808 nm) irradiation at the power density of 0.8 W/cm(2) for 5 min. This study demonstrates that the coupling of inert Ru(II) polypyridyl complexes to gold nanospheres allows for the enhancement of two-photon luminescence and for efficient photothermal effect., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

In this paper, we describe a facile and rapid method for preparing In2S3 nanoparticles via ultrasound dispersion. This method allows us to prepare In2S3 nanoparticles from bulk indium and sulfur with ease and without using expensive agents and in a short time. The possible growing mechanism of the In2S3 nanoparticles was presented. In addition, we provide detailed characterizations including TEM, XRD, TG-DTA, and XPS to study the shape, composition and structure of In2S3 nanoparticles. We also studied the tribology property of In2S3 nanoparticles made using this novel recipe.

Nickel (Ni) nanoparticles can be enriched on the surface of iron-based frictional pairs, which provides the possibility to get rid of the competitive adsorption between the polar species of vegetable oil and the surface-active nano-additives thereon. In this paper, nickel acetylacetonate was used as a precursor to in-situ synthesize nickel nanoparticles with an average diameter of about 12 nm in rapeseed oil (RO) as the reducing agent, surface modifier, and solvent as well. The tribological properties of the as-synthesized Ni nanoparticles were evaluated with a four-ball tribometer, and their tribomechanism was investigated based on the characterizations of the tribofilm on rubbed steel surfaces by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It was found that the Ni nanoparticles in-situ prepared in the RO with a mass fraction of 0.3% can reduce the wear scar diameter (WSD) of the steel ball by 36%. This is because, on the one hand, the Ni nanoparticles are adsorbed on the rubbed steel surfaces to repair or fill up the micro-pits and grooves thereon. On the other hand, Ni nanoparticles participate in tribochemical reactions with atmospheric O and steel substrate to form the tribochemical reaction film on the rubbed steel surfaces with the assistance of friction-induced heat and applied normal load. In addition, an amorphous carbon film is formed on the rubbed surface via the carbonization of base oil under the catalysis of Ni nanoparticles. The adsorbed Ni layer, the tribochemical reaction film, and the carbon layer comprise a composite tribofilm composed of amorphous carbon, polar fatty acid, metallic nickel, iron oxides, and nickel oxides on the rubbed steel surfaces, which contributes to significantly improving the antiwear ability and load-carrying capacity of the RO for the steel–steel sliding pair. [ABSTRACT FROM AUTHOR]

In this paper, to solve the problem that di‐n‐hexadecyldithiophosphate (DDP)‐modified Cu nanoparticles initially used as oil‐based lubricant additive cannot be directly used in water‐based lubricants, we adopt a water‐in‐oil reverse micro‐emulsion method to incorporate hydrophobic Cu nanoparticles into silica spheres for obtaining water‐dispersible Cu@SiO2 nanoparticles. The effects of reaction conditions on the morphology and microstructure of Cu@SiO2 nanoparticles were investigated. Furthermore, the tribological properties of the as‐prepared Cu@SiO2 nanoparticles as a lubricant additive in distilled water were investigated with a UMT‐2MT tribometer. Results indicate that the as‐prepared Cu@SiO2 nanoparticles exhibit good dispersion stability and antioxidant ability in distilled water. Besides, Cu@SiO2 nanoparticles can significantly improve the tribological properties of distilled water, which is attributed to the formation of a protective and lubricious film consisting of Cu, FeS and SiO2 on the rubbed steel surface. [ABSTRACT FROM AUTHOR]

Efficient and sustainable use of water-based lubricants is essential for energy efficiency. Therefore, the use of water-lubricated mechanical systems instead of conventional oil lubricants is extremely attractive from the viewpoint of resource conservation. In this study, water-soluble Cu nanoparticles of size approximately 3 nm were prepared at room temperature (around 25 °C) via in-situ surface modification. The tribological behavior of the as-synthesized Cu nanoparticles as an additive in distilled water was evaluated using a universal micro-tribotester. The results show that the as-synthesized Cu nanoparticles, as a water-based lubricant additive, can significantly improve the tribological properties of distilled water. In particular, the lowest friction coefficient of 0.06 was obtained via lubrication with a concentration of 0.6 wt% of Cu nanoparticles in distilled water, which is a reduction of 80.6% compared with that obtained via lubrication with distilled water alone. It is considered that some Cu nanoparticles entered the contact area of the friction pairs to form a complex lubricating film and prevent direct contact of the friction pairs. Furthermore, some Cu nanoparticles in the solution accelerate the heat transfer process, which also results in good tribological properties. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to study the tribological properties of Cu nanoparticles (NPs) as lubricant additives in three kinds of commercially available lubricants.Design/methodology/approach A four-ball machine is used to estimate the tribological properties of Cu NPs as lubricant additives in three kinds of commercially available lubricants. Three-dimensional optical profiler and electrical contact resistance are evaluated to investigate the morphology of the worn surfaces and the influence of Cu NPs on tribofilms.Findings Wear tests show that the addition of Cu NPs as lubricant additives could reduce wear and increase load-carrying capacity of commercially available lubricants remarkably, indicating that Cu NPs have a good compatibility with the existing lubricant additives in commercially available lubricants.Originality/value The tribological properties of Cu NPs as lubricant additives in three kinds of commercially available lubricants were investigated in this paper. These results are reliable and can be very helpful for application of Cu NPs as lubricant additives in industry. [ABSTRACT FROM AUTHOR]

Cu nanoparticle surface-capped by methoxylpolyethyleneglycol xanthate was synthesized using in situ surface-modification technique. The size, morphology and phase structure of as-prepared Cu nanoparticle were analyzed by means of X-ray diffraction and transmission electron microscopy. The tribological properties of as-synthesized Cu nanoparticle as an additive in distilled water were investigated with a four-ball machine, and the morphology and elemental composition of worn steel surfaces were examined using X-ray photoelectron spectroscopy and scanning electron microscope equipped with an energy-dispersive spectrometer attachment. Results show that as-synthesized Cu nanoparticle as a water-based lubricant additive is able to significantly improve the tribological properties and load-carrying capacity of distilled water, which is ascribed to the deposition of Cu nanoparticles on steel sliding surfaces giving rise to a protective and lubricious Cu layer thereon. In the meantime, they may also tribochemically react with rubbing steel surfaces to generate a boundary lubricating film consisting of Cu, FeS and FeSO on the rubbed steel surface, which helps to result in greatly improved tribological properties of distilled water, thereby reducing friction and wear of the steel-steel pair. [ABSTRACT FROM AUTHOR]

Cu nanoparticles surface-capped by alkanethiols were synthesized using ligand exchange method in a two-phase system. The effects of synthetic conditions, including the pH value of CuSO4 solution, the ratio of cetyltrimethyl ammonium bromide to CuSO4, and reaction temperature, on the size and shape of as-synthesized Cu nanoparticles were investigated. As-synthesized Cu nanoparticles surface-capped by alkanethiols with different chain lengths (C xS-Cu) were characterized by means of X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectrometry, and ultraviolet-visible light spectrometry. The tribological behavior of C xS-Cu as an additive in liquid paraffin was evaluated with a four-ball machine. Results indicate that cetyltrimethyl ammonium bromide plays an important role in controlling the dispersion of Cu nanoparticles before adding modifier octanethiol into the reaction solution. C xS-Cu nanoparticles as additive in liquid paraffin possess excellent antiwear and friction-reduction performance because of the deposition of nano-Cu with low melting point on worn steel surface leading to the formation of a self-repairing protective layer thereon. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Water-soluble LaF nanoparticles surface-capped by two kinds of dialkyl polyoxyethylene glycol thiophosphate ester (denoted as DTP-10 and DTP-20) were synthesized via a surface-modification method. The morphology and microstructure of resultant surface-modified LaF nanoparticles (denoted as LaDTP-10 and LaDTP-20) were characterized by means of X-ray powder diffraction, transmission electron microscopy, and Fourier transform infrared spectrometry, and their thermal stability was examined by thermogravimetric analysis. Moreover, the tribological properties of as-synthesized LaF nanoparticles as additives in distilled water were evaluated with a four-ball friction and wear tester, and the morphology of wear scar and the chemical states of some typical elements thereon were investigated by scanning electron microscopy and X-ray photoelectron spectroscopy. It has been found that as-prepared LaDTP-10 and LaDTP-20 nanoparticles have a size of 19.6 and 8.5 nm, respectively, and they have good dispensability in distilled water. Moreover, as-synthesized LaDTP-10 and LaDTP-20 nanoparticles as lubricant additives in distilled water exhibit good friction reducing, antiwear, and extreme pressure properties as well as high load-carrying capacity even at a concentration of 1 % (mass fraction). This is because LaF nanoparticles can be deposited on sliding steel surfaces to afford a surface protective layer, and they may also tribochemically react with rubbing steel surfaces to generate a boundary lubricating film mainly composed of phosphate, sulfide, sulfate, LaO, and LaF. Therefore, it is feasible for LaDTP-10 and LaDTP-20 nanoparticles to be used as water-soluble lubricant additives under harsh conditions. [ABSTRACT FROM AUTHOR]

Nickel-based nanolubricants containing size-tunable monodispersed nickel nanoparticles were in situ synthesized in poly-alpha-olefin (denoted as PAO6) via a simple one-step thermal decomposition method with Ni(HCOO)·2HO as the Ni source, PAO6 as base oil, as well as oleylamine and oleic acid as the surface-capping agents. The size-dependent tribological properties of as-synthesized Ni-based nanolubricants were evaluated with a four-ball friction and wear tester. The morphology of wear scar and chemical states of some typical elements on worn steel surfaces were analyzed by scanning electron microscopy and X-ray photoelectron spectroscopy. The morphology and structure of Ni nanoparticles separated from as-synthesized nanolubricants were characterized by means of transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectrometry. It has been found that, when the volume of PAO6 in the reaction system is adjusted as 80, 40 and 20 mL, respectively, the size (average diameter) of Ni nanoparticles can be tuned from 7.5 to 13.5 and 28.5 nm. Ni nanoparticles separated from as-synthesized nanolubricants consist of face-centered cubic nanocrystal and have good dispersibility in a variety of organic solvents and good thermal stability as well. Moreover, as-synthesized Nickel-based nanolubricants exhibit good antiwear behavior even at a low Ni concentration of 0.05 % (mass fraction). This is because surface-capped Ni nanoparticles in as-prepared nanolubricants are able to release highly active Ni nanocores and O- and N-containing organic modifying agents that can readily form boundary lubricating film on sliding steel surfaces. In the meantime, Ni nanoparticles with a smaller size are of high surface activity and can be readily deposited on sliding steel surfaces to form a stable and continuous protective layer thereon. As a result, both the boundary lubricating film and the chemically adsorbed and deposited Ni layer contribute to greatly improve the antiwear behavior and load-carrying capacity of PAO6 base stock. [ABSTRACT FROM AUTHOR]

Oil-soluble Cu nanoparticles without phosphorus and sulphur elements were prepared using in situ surface-modification technique with hydrazine hydrate as a reductant and tetradecyl hydroxamic acid (THA) as a modifier. The phase composition, microstructure, and chemical structure of as-synthesized Cu nanoparticles (coded as THA-capped Cu or THA-capped nano-Cu) were analyzed by means of X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectrometry. The thermal stability of THA-capped Cu was examined using thermogravimetric analysis and differential thermal analysis. The antiwear ability of THA-capped Cu as an additive in liquid paraffin was examined using a four-ball machine, and the morphology of worn steel balls was examined using a scanning electron microscope, an energy dispersive spectrometer and an X-ray photoelectron spectroscopy. It has been found that THA-capped Cu can be well dispersed in some organic solvents. As-synthesized THA-capped Cu as an environmentally friendly additive in liquid paraffin shows excellent antiwear ability for the steel-steel contact. Besides, Cu nanoparticles are able to deposit and fill up micropits and grooves on steel sliding surfaces under a higher load and hence greatly reduced wear of the steel-steel pair thereat by way of self-repairing of worn surfaces of the steel-steel frictional pair, showing promising application as an environmentally acceptable lubricating oil additive. [ABSTRACT FROM AUTHOR]

The tribological behaviors of various long chain organic molecule LB films, organic molecule modified inorganic nanoparticle LB films, and the C60-LB films were systematically investigated. The correlation between the structure and tribological behavior of the LB films has been explored, while the structural changes of the LB films during friction process were analyzed with Fourier transform infrared (FTIR) microscope. Three kinds of C60-LB films were prepared; its micro-frictional behaviors were investigated by AFM. As the results, the tribological behavior of long chain organic molecule LB films is highly dependent on the molecular chain length and the characteristics of the polar end groups. The optimal tribological behavior is reached at a balanced stiffness and toughness of the molecular chain, which is also related to the bonding strength of the LB film to the substrate. The LB films of nanoparticles modified with organic molecules are superior to long chain organic molecule ones in terms of resisting wear. This is attributed to the enhanced load-carrying capacity of the inorganic nanocores in the LB films of nanoparticles modified with organic molecules. The tribochemical changes including ordering and partial decomposition of the organic modifier have been observed in the sliding of the LB films of inorganic nanoparticles modified with organic molecules against steel. C60-LB film shows excellent tribological behavior, which is highly dependent on the interaction between the C60 nanocluster and the organic long chain molecules. [Copyright &y& Elsevier]

Abstract: Monodispersed and size-controlled Ag2S nanoparticles were synthesized successfully via a green and simple surfactant-free solventless thermolysis of silver xanthates as single-source precursors. As-prepared Ag2S nanoparticles were characterized by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectrometry. Moreover, a possible growth mechanism of Ag2S nanoparticles was proposed. It has been found that the size of Ag2S nanoparticles can be effectively controlled by changing the alkyl chain length of the precursors. Ag2S nanoparticles prepared from silver carnaubyl xanthate have the smallest mean diameter of 8.9±1.2nm, while the same products obtained from silver hexadecyl xanthate and silver octyl xanthate have a larger mean diameter of 19.5±0.9nm and 48.3±3.6nm, respectively. [Copyright &y& Elsevier]

Abstract: The present study reports a very simple and low-cost dip-coating method for the preparation of fluorine-free water-repellent SiO2 nanoparticle coating. The coating has a high water contact angle of 169° and a sliding angle of 7°, showing superhydrophobic property. The coating demonstrates good adhesion on substrates and the long-term stability. Importantly, the coating also demonstrates superhydrophobicity in the wide pH range of corrosive liquids. It is found that a piece of glass coated with superhydrophobic coatings cannot only float freely on water surface but also exhibit striking loading capacities. [Copyright &y& Elsevier]

Abstract: Hydrophilic silica nanoparticles (abridged as nano-SiO2) surface-capped with epoxide were dispersed in the solution of epoxy resin (abridged as EP) in tetrahydrofuran under magnetic stirring. Resultant suspension of nano-SiO2 in EP was then coated onto the surface of glass slides and dried at 80°C in a vacuum oven for 2h, generating epoxy resin-nanosilica composite coatings (coded as EP/nano-SiO2). EP coating without nano-SiO2 was also prepared as a reference in the same manner. A water contact angle meter and a surface profiler were separately performed to measure the water contact angles and surface roughness of as-prepared EP/nano-SiO2 composite coatings. The friction and wear behavior of as-prepared EP/nano-SiO2 composite coatings sliding against steel in a ball-on-plate contact configuration under unlubricated condition was evaluated. Particularly, the effect of coating composition on the friction and wear behavior of the composite coatings was highlighted in relation to their microstructure and worn surface morphology examined by means of scanning electron microscopy. Results indicate that EP/nano-SiO2 composite coatings have a higher surface roughness and water contact angle than EP coating. The EP-SiO2 coatings doped with a proper amount of hydrophilic SiO2 nanoparticles show lower friction coefficient than EP coating. However, the introduction of surface-capped nanosilica as the filler results in inconsistent change in the friction coefficient and wear rate of the filled EP-matrix composites; and it needs further study to achieve well balanced friction-reducing and antiwear abilities of the composite coatings for tribological applications. [Copyright &y& Elsevier]

Abstract: Hydrophobic polyelectrolyte multilayers (PEMs) doped with Cu nanoparticles and modified with fluoroalkylsilane were prepared by a series of reaction cycles which consist of cycling the PEMs-coated substrate in Cu2+ and NaBH4 solutions, where the polyelectrolyte multilayers were constructed by alternate pipetting of the solutions of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrene sulfonate) onto a spinning substrate. The as-prepared hydrophobic surfaces were characterized by means of X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurement. The micro-friction and macro-tribological behavior of the multilayers were investigated. Results indicate that the micro-tribological behavior of the PEMs obeys the modified Amonton''s Law, and the macro-tribological behavior of the Cu nanoparticles-doped hydrophobic PEMs is closely related to the wettability. Namely, the more hydrophobic the surfaces are, the longer the antiwear life is. Furthermore, the hydrophobic surfaces have lower friction coefficient under water lubrication than under dry-sliding. The reason lies in that the hydrophobic PEMs have low surface energy and less energy loss during sliding under water lubrication, leading to a lower friction coefficient. [Copyright &y& Elsevier]

Abstract: Superhydrophobic poly(methyl methacrylate)-SiO2 (coded as PMMA-SiO2) nanocomposite films with micro-nanohierarchical structure were prepared via a simple approach in the absence of low surface-energy compounds. By spin-coating the suspension of hydrophobic silica (SiO2) nanoparticles dispersed in PMMA solution, target nanocomposite films were obtained on glass slides. The wetting behavior of PMMA-SiO2 nanocomposite films was investigated in relation to the dosage of SiO2 nanoparticles dispersed in PMMA solution. It was found that hydrophilic PMMA film was transferred to superhydrophobic PMMA-SiO2 nanocomposite films when hydrophobic SiO2 nanoparticles were introduced into the PMMA solution at a high enough dosage (0.2g and above). Resultant PMMA-SiO2 nanocomposite films had a static water contact angle of above 162°, showing promising applications in selfcleaning and waterproof for outer wall of building, outer covering for automobile, sanitary wares, and so forth. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we describe a facile and rapid method for preparing In2S3 nanoparticles via ultrasound dispersion. This method allows us to prepare In2S3 nanoparticles from bulk indium and sulfur with ease and without using expensive agents and in a short time. The possible growing mechanism of the In2S3 nanoparticles was presented. In addition, we provide detailed characterizations including TEM, XRD, TG–DTA, and XPS to study the shape, composition and structure of In2S3 nanoparticles. We also studied the tribology property of In2S3 nanoparticles made using this novel recipe. [Copyright &y& Elsevier]

Abstract: Polyelectrolyte multilayers (PEMs) fabricated by spin-assisted layer-by-layer assembly technique were used as nanoreactors for in situ synthesis of Cu nanoparticles, allowing generation of Cu nanoparticles doped composite, denoted as Cu-nanoparticles PEMs. Thus chemical reaction within the PEMs was initiated by a series of reaction cycles in which Cu2+ was absorbed into the polymer-coated silicon substrate and reduced in NaBH4 solution. The surface of Cu-nanoparticles PEMs was modified by heptadecafluorodecyl-trimethoxysilane (FAS-17) with low surface energy, generating a hydrophobic film. The adhesion and nano-friction behavior of the hydrophobic film was investigated using an atomic force microscope, while its macro-tribological behavior sliding against stainless steel under dry- and distilled-water-lubricated conditions was investigated using a UMT-2 test rig. It was found that Cu-nanoparticles PEMs modified with FAS-17 has a lower friction and higher adhesion than that without modification. Moreover, the hydrophobic film possesses lower friction coefficient under water-lubrication and higher friction coefficient under dry-sliding than the hydrophilic film under the same conditions, which could be mainly due to the difference in the surface energy. The titled hydrophobic films with low adhesion and friction would have potential application in micro/nano-electro-mechanical systems. [Copyright &y& Elsevier]

Abstract: Polyelectrolyte multilayers (PEMs) fabricated by spin-assisted layer-by-layer assembly technique were used as nanoreactors for in-situ synthesis Cu nanoparticles. Chemical reaction within the PEMs was initiated by a reaction cycle in which Cu2+ was absorbed into the polymer-coated substrate and then reduced in NaBH4 solutions. Repeating the above process resulted in an increase in density of the nanoparticles and further growth in the dimension of the particles initially formed. So, different Cu-nanoparticle polyelectrolyte multilayers were formed in the process. The friction and wear properties of Cu-nanoparticle PEMs formed by different reaction cycles were investigated on a microtribometer against a stainless steel ball. The PEMs reinforced with Cu nanoparticles, prepared under the best preparation conditions, possess good tribological behavior, because of the weakened adhesion between the PEMs and the substrate and decreased mobility of the polymeric chains in the presence of excessive Cu nanoparticles generated at larger reaction cycles. [Copyright &y& Elsevier]

Abstract: Copper ions-loaded polyelectrolyte multilayer films (PEMs) of poly(acrylic acid), coded as PAA, and poly(diallyldimethylammonium chloride), coded as PDDA, were constructed on silicon substrate via layer-by-layer (LBL) self-assembly, using CuCl2 blended in the electrolyte solution as the source of Cu2+. Cu(OH)2 nanoparticles were then in-situ synthesized in the multilayer films by immersion of the copper ions-loaded PEMs into 0.1 M NaOH solution. The Cu2+-loaded PAA/PDDA multilayer films and those doped with in-situ Cu(OH)2 nanoparticles were characterized by means of ultraviolet–visible light (UV–vis) absorption spectrometry, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The friction and wear behaviors of the multilayer films sliding against 440C stainless steel counterparts were evaluated using a UMT-2 multifunctional micro tribometer. Results indicate that the Cu2+-loaded PAA/PDDA multilayers with a bilayer number of 2–8 show similar UV–vis absorbance features, and no noticeable accumulation in the amount of Cu2+ occurs during the fabrication of the multilayers, possibly owing to a weak bonding between Cu2+ and –COO−. The blue-shift of the absorption peak of –COO−–Cu2+ band, observed for PAA/PDDA multiplayer films, becomes more obvious after being doped with in-situ Cu(OH)2 nanoparticles. The final Cu(OH)2 nanoparticles-doped PAA/PDDA multilayer films have excellent friction-reducing and antiwear abilities, possibly owing to the modification and refining of their morphology and microstructure by the in-situ doped Cu(OH)2 nanoparticles. The present approach could be extended to incorporate nanoparticles of other types of metal ions into the final PEMs to realize multifunctionalization. [Copyright &y& Elsevier]

Abstract: The pristine polyelectrolyte multilayers (PEMs) were prepared by layer-by-layer deposition technique. The ZnS nanoparticles were in situ-synthesized in the pristine PEMs, and the composite was denoted as ZnS-filled PEMs. The friction and wear properties of ZnS-filled PEMs were investigated on a UMT-2 against stainless steel ball. The morphologies of the wear traces were observed by scanning electron microscope. It was found that ZnS-filled PEMs exhibit higher antiwear life than unfilled ones. This should be attributed to the ZnS nanoparticles formed in the PEMs enhancing the load-carrying capacity. Moreover, the PEMs with three reaction cycles have considerably lower friction coefficient and higher antiwear life than the PEMs with six reaction cycles, that is to say, an optimum amount of ZnS nanoparticles within PEMs can improve the tribological performance greatly. [Copyright &y& Elsevier]

Abstract: Langmuir-Blodgett (LB) films of dialkyldithiophosphate (DDP) modified Cu nanoparticles were prepared. The structure, microfrictional behaviors and adhesion of the LB films were investigated by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and atomic/friction force microscopy (AFM/FFM). Our results showed that the modified Cu nanoparticles have a typical core–shell structure and fine film-forming ability. The images of AFM/FFM showed that LB films of modified Cu nanoparticles were composed of many nanoparticles arranged closely and orderly and the nanoparticles had favorable behaviors of lower friction. The friction loop of the films indicated that the friction force was affected prominently by the surface slope of the Cu nanoparticles and the microfrictional behaviors showed obvious “ratchet effect”. The adhesion experiment showed that the modified Cu nanoparticle had a very small adhesive force. [Copyright &y& Elsevier]

Abstract: Copper nanoparticles containing diamond-like carbon (Cu-DLC) films have been prepared on the Si substrate using electrochemical deposition method by choosing dimethylsulfoxide as carbon source and acetonitrile solution of [Cu(CH3CN)4]ClO4 as dopant at relatively low voltage (150V). The composition, structure and morphology of the film have been investigated by X-ray photoelectron spectroscope (XPS), Fourier transform infrared (FTIR), Raman scattering spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The results show that the copper element was embedded in the amorphous carbon film and the codeposition rate of carbon film and copper cluster was relatively high. Furthermore, a ball-on-disc test was employed to obtain information about the frictional properties of the Cu-DLC films. The growth mechanisms of the Cu-DLC films were also discussed. [Copyright &y& Elsevier]

This work was to investigate the interactions of Cu NPs with dispersant, detergent, antioxidant, friction modifier, viscosity index improver on tribological performance and some physicochemical properties of diisooctylsebacate (DIOS). The results indicate that Cu NPs and most additives have a synergy on tribological performance. Whereas, Cu NPs and dispersant or detergent can only enhance wear resistance. When phenols antioxidant, viscosity index improver and ZDDP are added together with Cu NPs, the antioxidation performance of DIOS can be distinctly improved. Nevertheless, amines antioxidant and Cu NPs exhibit antagonistic effect. The kinematic viscosity of DIOS can be enhanced by adding viscosity index improver together with Cu NPs. The synergetic effects between ZDDP/MoDTC and Cu NPs are both obvious in many properties. • Dispersant/detergent-Cu NPs enhance wear resistance, but lower lubricating property. • Antioxidant-Cu NPs improve tribological property, but weaken antioxidation performance. • Cu NPs can further enhance friction modifiers not wear resistance but lubricating ability. • The synergy between viscosity index improver and Cu NPs is obvious in many properties. • ZDDP-Cu NPs can synergistically improve lubricating ability and anti-oxidation property. [ABSTRACT FROM AUTHOR]

In order to overcome the poor lubricity of zinc dialkyldithiophosphate (ZDDP) in aluminum contacts, ZnO nanoparticles (ZODDP) modified with dialkyldithiophosphoric acid were prepared through one step process from ZDDP. Compared with ZDDP the sulfur and phosphorus contents of ZODDP decreased by 77.9%～82.8% and 77.3～80.7%. respectively. The tribological properties of ZODDP as the additives of diisooctyl sebacate (DIOS) in steel-aluminum contacts were evaluated on ball-on-disk tribometer. Compared with ZDDP the friction coefficient (cof) and wear rate (wr) of ZODDP decreased by 10.37% and 71.74% respectively. The ZnO nano cores in ZODDP enriched on frictional surface, which avoided the direct contact between friction pairs. The weak chemical interaction between ZnO nano-core and modifier promoted the tribological reaction between modifier and aluminum disks. ZODDP is expected to be a cheap and easily available lubricant additive for aluminium-based materials lubricating. • An environmentally friendly nano-additive ZODDP was prepared by in situ oxidation of ZDDP through simple one-step process. • Compared with ZDDP the sulfur and phosphorus contents of ZODDP decreased by 81.63% and 78.55% respectively. • Compared with that of ZDDP the cof and wr of ZODDP as additives in DIOS decreased by 10.37% and 71.74% respectively. • Nano-additive ZODDP overcomes the problem that ZDDP cannot form effective friction film on aluminum-based friction pair. [ABSTRACT FROM AUTHOR]