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Wu W, Liu J, Lin X, He Z, Zhang H, Ji L, Gong P, Zhou F, Liu W. Dual-functional MOFs-based hybrid microgel advances aqueous lubrication and anti-inflammation. J Colloid Interface Sci 2023; 644:200-210. [PMID: 37116318 DOI: 10.1016/j.jcis.2023.04.071] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 04/03/2023] [Accepted: 04/17/2023] [Indexed: 04/30/2023]
Abstract
This paper demonstrates the hybridization of copolymer microgel with drug-loaded metal-organic frameworks nanoparticles that can achieve excellent aqueous lubricating performance and anti-inflammatory effect for synergistic treatment of osteoarthritis (OA). Poly(ethylene glycol)-graft-poly(N-isopropylacrylamide) (PEG-g-PNIPAm) microgel layer is grown on the MIL-101(Cr) surface via one-pot soap-free emulsion polymerization method. The lower critical solution temperature of the MIL-101(Cr)@PEG-g-PNIPAm hybrid is raised significantly by incorporating PEG chains into the PNIPAm microgel matrix, which greatly enhances the high-temperature aqueous dispersion stability. The hybrid microgel demonstrated reversibly thermo-sensitive swelling-collapsing behavior to modulate the optical properties and hydrodynamic size. Using as aqueous lubricating additives, the hybrid reduces over 64% and 97% in friction coefficient and wear volume. Also, the hybrid supports desirable temperature-controlled lubrication modulation due to their reversible thermo-responsive behavior, which is benefit to joint lubrication of OA. After encapsulating anti-inflammatory diclofenac sodium (DS), the DS-MIL-101(Cr)@PEG-g-PNIPAm shows thermo-responsive drug release in aqueous media, which can improve the drug-delivery efficiency. By co-culturing the DS-loaded hybrid with human normal chondrocytes, we demonstrate good biocompatibility and anti-inflammatory effect on the chondrocytes with inflammation by regulating the expression of OA-related genes and proteins. Our work establishes multifunctional MOFs-based hybrid microgel systems for advanced colloids modulation and biomedical application.
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Affiliation(s)
- Wei Wu
- State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China
| | - Jianxi Liu
- State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China.
| | - Xiao Lin
- Key Lab for Space Biosciences and Biotechnology, Research Center for Special Medicine and Health Systems Engineering, School of Life Sciences, Northwestern Polytechnical University, Xi'an 710072, PR China
| | - Zhengze He
- State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China
| | - Hui Zhang
- Key Lab for Space Biosciences and Biotechnology, Research Center for Special Medicine and Health Systems Engineering, School of Life Sciences, Northwestern Polytechnical University, Xi'an 710072, PR China
| | - Le Ji
- Department of Orthopedic Surgery, Shaanxi Provincial People's Hospital, Xi'an 710068, PR China
| | - Peiwei Gong
- State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China
| | - Feng Zhou
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China
| | - Weimin Liu
- State Key Laboratory of Solidification Processing, Center of Advanced Lubrication and Seal Materials, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, PR China; State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, PR China
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Du C, Yu T, Zhang L, Deng H, Shen R, Li X, Feng Y, Wang D. Macroscale Superlubricity with Ultralow Wear and Ultrashort Running-In Period (∼1 s) through Phytic Acid-Based Complex Green Liquid Lubricants. ACS APPLIED MATERIALS & INTERFACES 2023; 15:10302-10314. [PMID: 36755437 DOI: 10.1021/acsami.2c22402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Liquid superlubricity has attracted much attention, due to its ability to significantly reduce friction on the macroscale. However, the severe wear caused by the long running-in period is still one of the bottlenecks restricting the practical application of liquid superlubricating materials. In this work, the obtained polyethylene glycol-phytic acid (PEG-PA) composite liquid lubricants showed outstanding superlubricating properties (μ ≈ 0.006) for Si3N4/glass friction pairs with an ultrashort running-in period (∼1 s) under high Hertzian contact pressure of ∼758 MPa. More importantly, even after up to 12 h (∼700 m of travel), only about 100 nm deep wear scars were found on the surface of the glass sheet (wear rate = 2.51× 10-9 mm3 N-1 m-1). From the molecular point of view, the water molecules anchored between the two friction pairs have extremely low shear force during the friction process, and the strong hydrogen bond interaction between PEG and PA greatly improves the bearing capacity of the lubricant. This work addresses the challenge of liquid superlubricant simultaneously exhibiting low shear force and high load-carrying capacity and makes it possible to obtain liquid superlubrication performance with an extremely short running-in time.
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Affiliation(s)
- Changhe Du
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Tongtong Yu
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Qingdao Center of Resource Chemistry and New Materials, Qingdao 266104, China
| | - Liqiang Zhang
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Qingdao Center of Resource Chemistry and New Materials, Qingdao 266104, China
| | - Haoyu Deng
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ruilin Shen
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
| | - Xiaojuan Li
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yange Feng
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Qingdao Center of Resource Chemistry and New Materials, Qingdao 266104, China
| | - Daoai Wang
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
- Qingdao Center of Resource Chemistry and New Materials, Qingdao 266104, China
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Kreivaitis R, Kupčinskas A, Gumbytė M, Treinytė J. Tribological properties of bis(2-hydroxyethyl)ammonium oleate in glycerol and polyethylene glycol aqueous solutions. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Wen X, Bai P, Meng Y, Ma L, Tian Y. High-Temperature Superlubricity Realized with Chlorinated-Phenyl and Methyl-Terminated Silicone Oil and Hydrogen-Ion Running-in. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10043-10051. [PMID: 35915968 DOI: 10.1021/acs.langmuir.2c01523] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ceramic friction pairs lubricated with chlorinated-phenyl and methyl-terminated silicone oil (CPSO) systems have potential applications in the aerospace industry. In this study, the effects of the running-in process and temperature on the lubricating performance of CPSO were investigated. The superlubricity of Si3N4/sapphire lubricated with CPSO was realized at >190 °C after H+-ion running-in. The mechanism of this high-temperature superlubricity was investigated by determining the stable adsorption configurations and adsorption energies of CPSO on different surfaces using density functional theory calculations. Compared with that on the Si3N4 surface, the adsorption capacity of CPSO on the hydroxylated SiO2 surface generated by H+-ion running-in increased, whereas the steric hindrance decreased. The viscosity-temperature curve of CPSO was measured, wherein the viscosity and pressure-viscosity coefficient of CPSO considerably decreased with increasing temperature, leading to high-temperature superlubricity in a wide speed/load range. This is the first paper to report oil-based superlubricity at temperatures of 190 °C, or even higher-temperature conditions. Furthermore, it provides guidance for the use of ceramic-CPSO systems in high-temperature conditions, including in the aerospace industry.
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Affiliation(s)
- Xiangli Wen
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Pengpeng Bai
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Yonggang Meng
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Liran Ma
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Yu Tian
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
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Bioinspired Bottlebrush Polymers for Aqueous Boundary Lubrication. Polymers (Basel) 2022; 14:polym14132724. [PMID: 35808769 PMCID: PMC9269121 DOI: 10.3390/polym14132724] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 06/30/2022] [Accepted: 07/01/2022] [Indexed: 01/30/2023] Open
Abstract
An extremely efficient lubrication system is achieved in synovial joints by means of bio-lubricants and sophisticated nanostructured surfaces that work together. Molecular bottlebrush structures play crucial roles for this superior tribosystem. For example, lubricin is an important bio-lubricant, and aggrecan associated with hyaluronan is important for the mechanical response of cartilage. Inspired by nature, synthetic bottlebrush polymers have been developed and excellent aqueous boundary lubrication has been achieved. In this review, we summarize recent experimental investigations of the interfacial lubrication properties of surfaces coated with bottlebrush bio-lubricants and bioinspired bottlebrush polymers. We also discuss recent advances in understanding intermolecular synergy in aqueous lubrication including natural and synthetic polymers. Finally, opportunities and challenges in developing efficient aqueous boundary lubrication systems are outlined.
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de Paula FH, de Freitas FA, Nunes DG, Iglauer S, Gramatges AP, Nascimento RS, Lachter ER. Alkyl glyceryl ethers as water-based lubricant additives in mixtures with xanthan gum. Colloids Surf A Physicochem Eng Asp 2022. [DOI: 10.1016/j.colsurfa.2021.127881] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Hu F, Lu H, Ye Z, Zhang S, Wang W, Gao L. Slow-release lubrication of artificial joints using self-healing polyvinyl alcohol/polyethylene glycol/ graphene oxide hydrogel. J Mech Behav Biomed Mater 2021; 124:104807. [PMID: 34492404 DOI: 10.1016/j.jmbbm.2021.104807] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 08/27/2021] [Accepted: 08/30/2021] [Indexed: 11/28/2022]
Abstract
New fabrication methods and lubrication materials must be developed to improve the lubrication performance of artificial joints and increase the lubrication duration. Herein, a novel polyvinyl alcohol/polyethylene glycol/graphene oxide (PVA/PEG/GO) hydrogel was prepared by a physical cross-linking method, and then the hydrogel and its sustained-release solution were used as lubricant for friction evaluation. The results demonstrated that the slow-release gel solution has good lubrication performance, and coefficient of friction (COF) is only 0.04, which is much lower than the COF of distilled water (about 0.08) under the same conditions. The structure characterization results revealed that no new materials are formed in the gel. The results of thermogravimetric analyses and differential scanning calorimetry demonstrated that the addition of GO may improve the network crosslinking structure of the PVA/PEG hydrogel and improve its mechanical strength. In addition, PVA/PEG/GO hydrogel has superior self-healing function. The self-healing hydrogel did not break again after being pulled under 200 G of weights. The PVA/PEG/GO hydrogel with excellent slow-release lubricating performance and self-healing properties provides a novel candidate for design of long-term lubricating artificial joints, and is expected to promote the progress of artificial joint lubrication applications.
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Affiliation(s)
- Feng Hu
- Group of Mechanical and Biomedical Engineering, Xi'an Key Laboratory of Modern Intelligent Textile Equipment, College of Mechanical and Electronic Engineering, Xi'an Polytechnic University, Xi'an, Shaanxi 710048, PR China
| | - Hailin Lu
- Group of Mechanical and Biomedical Engineering, Xi'an Key Laboratory of Modern Intelligent Textile Equipment, College of Mechanical and Electronic Engineering, Xi'an Polytechnic University, Xi'an, Shaanxi 710048, PR China.
| | - Zishuo Ye
- Group of Mechanical and Biomedical Engineering, Xi'an Key Laboratory of Modern Intelligent Textile Equipment, College of Mechanical and Electronic Engineering, Xi'an Polytechnic University, Xi'an, Shaanxi 710048, PR China
| | - Shoujing Zhang
- Group of Mechanical and Biomedical Engineering, Xi'an Key Laboratory of Modern Intelligent Textile Equipment, College of Mechanical and Electronic Engineering, Xi'an Polytechnic University, Xi'an, Shaanxi 710048, PR China
| | - Wenbo Wang
- College of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, 010021, PR China.
| | - Li Gao
- Department of Gynaecology and Obstetrics, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, PR China.
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Wen X, Bai P, Li Y, Cao H, Li S, Wang B, Fang J, Meng Y, Ma L, Tian Y. Effects of Abrasive Particles on Liquid Superlubricity and Mechanisms for Their Removal. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3628-3636. [PMID: 33733780 DOI: 10.1021/acs.langmuir.0c03607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Liquid superlubricity results in a near-frictionless lubrication state, which can greatly reduce friction and wear under aqueous conditions. However, during the running-in process, a large number of abrasive particles are generated, and because these may lead to a breakdown in superlubricity performance, they should be effectively removed. In this paper, the morphology, size, and composition of abrasive particles were verified using scanning electron microscopy with energy-dispersive X-ray spectroscopy, and their influence on liquid superlubricity was explored through friction tests. Subsequently, different solvents were used to remove the abrasive particles, and the optimal cleaning process was determined by macroscopic tribo-tests and microscopic analysis. Finally, droplet-spreading experiments and a force-curve analysis were carried out to understand the abrasive-particle removal mechanism by different solvents. We found that SiO2 was the main component in the abrasive particles, and micron-sized SiO2 particles resulted in random "wave peaks" in the coefficient of friction and, thus, the superlubricity. Absolute ethanol + ultrapure water was determined to be the optimal solvent for effectively removing abrasive particles from friction-pair surfaces and helped the lubricant in exhibiting an ultralow friction coefficient for long periods of time. We proposed a "wedge" and "wrap" model to explain the abrasive-particle removal mechanism of different solvents. The SiO2 removal mechanism outlined in this study can be applied under aqueous conditions to improve the stability and durability of liquid superlubricity in practical engineering applications.
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Affiliation(s)
- Xiangli Wen
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Pengpeng Bai
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Yuanzhe Li
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Hui Cao
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Shaowei Li
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Bin Wang
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Jingbo Fang
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Yonggang Meng
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Liran Ma
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Yu Tian
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
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Cao H, Xu W, Guo X. The wormlike micelles formed using an ionic liquid surfactant and polar organic solvents at low temperature without additives and their lubricant properties. SOFT MATTER 2021; 17:1437-1444. [PMID: 33326550 DOI: 10.1039/d0sm01825b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Wormlike micelles (or reverse wormlike micelles) are flexible cylindrical chains that are normally formed in water (or a nonpolar organic solvent) at 25.0 °C or above; the formation of wormlike micelles at lower temperatures is rare. Here, we have reported wormlike micelles formed at low temperature using an ionic liquid surfactant (1-octadecyl-3-nonyl imidazolium bromide) in polar organic solvents (including 1,3-propanediol, 1,2-propylene glycol, N,N-dimethylformamide, and glycerol/1,2-propylene glycol mixture) in the absence of any additives. The viscoelasticity and morphology of the wormlike micelles were studied using rheology, small-angle X-ray scattering, and cryo-transmission electron microscopy. The viscoelastic properties of the wormlike micelles in polar solvents are affected by the solvent type (or the weight ratio of glycerol to 1,2-propylene glycol), surfactant concentration, and temperature. Moreover, the G' and G'' crossover twice in the dynamic curves, which is different from the case in water. The first crossover (at low frequency) corresponds to the relaxation time for the alkyl chains to disentangle from the transient network, and the second crossover (at high frequency) is related to the segmental motion of the chains. Furthermore, the tribological performance of these wormlike micelles is investigated at low temperature. It is found that the protective film (formed by the physical adhesion of the wormlike micelles on the surface of friction disk pair) and the tribochemical reaction together lead to good antifriction and antiwear performance, which indicates the application prospects of these wormlike micelles in low-temperature lubrication.
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Affiliation(s)
- Huijiao Cao
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, P. R. China.
| | - Wenlin Xu
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, P. R. China.
| | - Xia Guo
- School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou, Jiangsu 225002, P. R. China.
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Han T, Yi S, Zhang C, Li J, Chen X, Luo J, Banquy X. Superlubrication obtained with mixtures of hydrated ions and polyethylene glycol solutions in the mixed and hydrodynamic lubrication regimes. J Colloid Interface Sci 2020; 579:479-488. [PMID: 32622097 DOI: 10.1016/j.jcis.2020.06.095] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 06/21/2020] [Accepted: 06/22/2020] [Indexed: 12/31/2022]
Abstract
HYPOTHESIS Superlubricity is known to dramatically reduce frictional energy consumption and to improve service life of mechanical devices and biological systems. However, reduction of wear during the running-in period of friction pairs, especially under high contact pressures, still remains an unresolved issue affecting all machines. EXPERIMENTS Here the lubrication, adsorption, and conformational properties of hydrated ions and polyethylene glycol (PEG) mixtures were evaluated at different mass fractions and concentrations of PEG and salts by ball-on-disc tribometer, ζ-potential, quartz crystal microbalance with dissipation (QCM-D), and dynamic light scatting (DLS) analyses. FINDINGS These mixtures exhibited superlubricity between Si3N4 and sapphire surfaces in a wide range of concentrations and ions valency. Interestingly, a running-in phase shorter than 1 min and low wear rate of 1.85 μm3/(N·m) were observed at contact pressures up to 555 MPa, significantly higher to earlier findings. PEG chains retain random coils filling the bulk of the interfacial film without strongly adsorbing on the interfaces but significantly increasing the viscosity of lubricating film, thereby favoring hydrodynamic lubrication. Hydrated ions are strongly adsorbed on the negatively charged ceramic surfaces, ensuring a sustained hydration effect maintaining superlubricity. The outstanding lubrication characteristics of the PEG/ions mixtures were attributed to the synergistic action of hydration and hydrodynamic lubrication, which appears as a promising avenue for developing new green lubricants and has implications for industrial and biological applications.
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Affiliation(s)
- Tianyi Han
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China; Faculty of Pharmacy, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
| | - Shuang Yi
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Chenhui Zhang
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
| | - Jinjin Li
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Xinchun Chen
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Jianbin Luo
- State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China
| | - Xavier Banquy
- Faculty of Pharmacy, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
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Lin W, Kampf N, Klein J. Designer Nanoparticles as Robust Superlubrication Vectors. ACS NANO 2020; 14:7008-7017. [PMID: 32412738 PMCID: PMC7315629 DOI: 10.1021/acsnano.0c01559] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 05/15/2020] [Indexed: 05/25/2023]
Abstract
Phosphatidylcholine lipid bilayers or liposomes at interfaces in aqueous environments can provide extremely efficient lubrication. This is attributed to the hydration lubrication mechanism acting at the highly hydrated phosphocholine-headgroup layers exposed at the outer surface of each bilayer. Micelles exposing such phosphocholine groups could be an attractive alternative to liposomes due to their much easier preparation and structure control, but all studies to date of surfactant micelles have revealed that at relatively low normal stresses the surface layers rupture and friction increases abruptly. Here, we examine surface interactions between three kinds of phosphocholine-exposing micelles with different designed structures: single-tail surfactant micelles, homo-oligomeric micelles, and block copolymer micelles. Normal and shear forces between mica surfaces immersed in solutions of these micelles were measured using a surface force balance. The adsorbed layers on the mica were imaged using atomic force microscope, revealing surface structures ranging from wormlike to spherical micelles. The block copolymer micelles showed relatively low coverage arising from their stabilizing corona and consequently poor lubrication (μ ∼ 10-1). In contrast, the surfactant and homo-oligomeric micelles fully covered the mica surface and demonstrated excellent lubrication (μ ∼ O(10-3)). However, while the boundary layer of single-tailed surfactant micelles degraded under moderate pressure, the homo-oligomeric micellar boundary layer was robust at all applied contact pressures in our study (up to about 5 MPa). We attribute the difference to the much greater energy required to remove a homo-oligomeric molecule from its micelle, resulting in far greater stability under pressure and shear.
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Affiliation(s)
- Weifeng Lin
- Department
of Materials and Interfaces, Weizmann Institute
of Science, Rehovot 76100, Israel
| | - Nir Kampf
- Department
of Materials and Interfaces, Weizmann Institute
of Science, Rehovot 76100, Israel
| | - Jacob Klein
- Department
of Materials and Interfaces, Weizmann Institute
of Science, Rehovot 76100, Israel
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12
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Li S, Bai P, Li Y, Jia W, Li X, Meng Y, Ma L, Tian Y. Extreme-Pressure Superlubricity of Polymer Solution Enhanced with Hydrated Salt Ions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:6765-6774. [PMID: 32460491 DOI: 10.1021/acs.langmuir.0c00887] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The development of new routes or materials to realize superlubricity under high contact pressure can result in energy-saving and reduction of emissions. In this study, superlubricity (μ = 0.0017) under extreme pressure (717 MPa, more than twice the previously reported liquid superlubricity) between the frictional pair of Si3N4/sapphire was achieved by prerunning-in with a H3PO4 (HP) solution followed by lubrication with an aqueous solution consisting of poly(vinyl alcohol) (PVA) and sodium chloride (NaCl). Under the same test condition, the aqueous PVA lubricant did not show superlubricity. Results of X-ray photoelectron spectroscopy and Raman spectroscopy indicate the formation of a PVA-adsorbed film at the frictional interface after lubrication with PVA but not after lubrication with PVA/NaCl, indicating competitive adsorption between hydrated Na+ ions and PVA molecules. The hydrated Na+ ions adsorbed preferentially to the solid surfaces, causing the transformation of the shear interface from a polymer film/polymer film to a solid/polymer film. Meanwhile, the hydrated Na+ ions also produced hydration repulsion force and induced low shear stress between the solid surfaces. Furthermore, NaCl increased the viscosity of the polymer lubricant, enhanced the hydrodynamic effect between interfaces, and decreased direct contact between the friction pair, causing a further reduction in friction. Thus, the superlubricity of the PVA/NaCl mixture is attributed to the combination of hydration and hydrodynamic effects. This study provides a novel route and mechanism for achieving extreme-pressure superlubricity at the macroscale, through the synergistic lubricating effect of hydrated ions and a polymer solution, propelling the industrial application of superlubricity.
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Affiliation(s)
- Shaowei Li
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Pengpeng Bai
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Yuanzhe Li
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Wenpeng Jia
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Xinxin Li
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Yonggang Meng
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Liran Ma
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
| | - Yu Tian
- State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
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14
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Shetty P, Mu L, Shi Y. Polyelectrolyte cellulose gel with PEG/water: Toward fully green lubricating grease. Carbohydr Polym 2020; 230:115670. [PMID: 31887933 DOI: 10.1016/j.carbpol.2019.115670] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 11/23/2019] [Accepted: 11/25/2019] [Indexed: 11/16/2022]
Abstract
Developing a fully green lubricant is an urgent need due to the growing consciousness of environmental protection and dwindling resources. In this work, fully green gel lubricants were developed out of cellulose derivatives as gelator and mixture of water and poly(ethylene glycol) 200 (PEG 200) as the base fluid. The non-ionic hydroxyethyl cellulose (HEC) and anionic sodium carboxymethyl cellulose (NaCMC) were chosen to understand the effect of ionic and non-ionic gelators on the thermal, rheological and the tribological properties of the gel lubricant. HEC or NaCMC is demonstrated as effective additive to reduce wear, stabilize friction coefficient and enhance the thermal stability of developed lubricants. It is shown that anionic gelator will result in producing lower friction and wear in comparison to non-ionic gelator, which may be attributed to the possible tribo-film formation due to the negative charge in the NaCMC molecules and its larger molecular weight.
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Affiliation(s)
- Pramod Shetty
- Division of Machine Elements, Luleå University of Technology, Luleå, 97187, Sweden
| | - Liwen Mu
- Division of Machine Elements, Luleå University of Technology, Luleå, 97187, Sweden.
| | - Yijun Shi
- Division of Machine Elements, Luleå University of Technology, Luleå, 97187, Sweden.
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15
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Jia W, Bai P, Zhang W, Ma L, Meng Y, Tian Y. On Lubrication States after a Running-In Process in Aqueous Lubrication. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15435-15443. [PMID: 31125241 DOI: 10.1021/acs.langmuir.9b01105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Recently, many studies have reported the ultralow friction coefficient of sliding friction between rigid solid surfaces in aqueous lubrication. A running-in process that goes through high-friction and friction-decreasing regions to a stable ultralow friction region is often required. However, the role of the friction-decreasing region is often ascribed to tribofilm formation in which complexity hindered the quantitative description of the running-in process and the prediction of its subsequent lubrication state. In this work, the frictional energy (Ef) dissipated in the running-in process of a poly(oligo(ethylene glycol) methyl ether acrylate) aqueous lubrication was related to the wear of solid surfaces under different conditions and lubrication states. Experimental results indicated that the high-friction region was in a boundary lubrication state, contributed to most of the wear, and significantly reduced the contact pressure, whereas the friction-decreasing region was in a mixed lubrication state, contributed only to the slight and slow removal of materials, and slightly reduced the contact pressure. Therefore, by establishing relationships among the wear scar diameter, Ef, and the Stribeck curve of the tribological system, the subsequent lubrication state after a running-in process under various working loads and sliding speeds could be quantitatively predicted. The running-in experiments with different aqueous lubrication systems showed good agreement with the prediction of this method. This investigation provides an effective method for the wear and lubrication state prediction after a running-in process, further proving the importance of the Stribeck curve for a lubrication system. This study may also have important implications for the strategy design of the running-in process in various industrial applications.
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Affiliation(s)
- Wenpeng Jia
- State Key Laboratory of Tribology, Department of Mechanical Engineering , Tsinghua University , Beijing 100084 , China
| | - Pengpeng Bai
- State Key Laboratory of Tribology, Department of Mechanical Engineering , Tsinghua University , Beijing 100084 , China
| | - Wenling Zhang
- Department of Chemical and Materials Engineering , University of Alberta , Edmonton , Alberta T6G 1H9 , Canada
| | - Liran Ma
- State Key Laboratory of Tribology, Department of Mechanical Engineering , Tsinghua University , Beijing 100084 , China
| | - Yonggang Meng
- State Key Laboratory of Tribology, Department of Mechanical Engineering , Tsinghua University , Beijing 100084 , China
| | - Yu Tian
- State Key Laboratory of Tribology, Department of Mechanical Engineering , Tsinghua University , Beijing 100084 , China
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16
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Liu W, Wang H, Liu Y, Li J, Erdemir A, Luo J. Mechanism of Superlubricity Conversion with Polyalkylene Glycol Aqueous Solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:11784-11790. [PMID: 31432683 DOI: 10.1021/acs.langmuir.9b01857] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this study, ultralow friction coefficient (COF, μ < 0.01) was obtained through polyalkylene glycol (PAG) aqueous solutions with different molecular weights (MWs) ranging from 270 to 3930 g·mol-1 under ambient conditions. With the increase in the MWs of PAG molecules, the threshold concentration to obtain this type of superlubric behavior gradually changed from 90 to 60 wt %. This phenomenon was closely related to the interaction between PAG chains and water molecules and the state of chemical binding. In the superlubricity system, superior load-bearing capacity was achieved at optimal threshold concentrations of all PAG aqueous solutions wherein multilayered adsorption layers that consisted of fully hydrated PAG molecules were formed on the sliding solid surfaces. With respect to the concentration below the threshold value, the existence of a shearing layer was indicated to play a significant role. Thus, the synergetic effect of sufficient adsorption of molecules and the unique shear rheology of the PAG aqueous solution were essential to achieve superlubricity.
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Affiliation(s)
- Wenrui Liu
- State Key Laboratory of Tribology , Tsinghua University , Beijing 100084 , China
| | - Hongdong Wang
- State Key Laboratory of Tribology , Tsinghua University , Beijing 100084 , China
- Energy Systems Division , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Yuhong Liu
- State Key Laboratory of Tribology , Tsinghua University , Beijing 100084 , China
| | - Jinjin Li
- State Key Laboratory of Tribology , Tsinghua University , Beijing 100084 , China
| | - Ali Erdemir
- Energy Systems Division , Argonne National Laboratory , Argonne , Illinois 60439 , United States
| | - Jianbin Luo
- State Key Laboratory of Tribology , Tsinghua University , Beijing 100084 , China
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17
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Zhang X, Dai Y. Recent development of brush polymers via polymerization of poly(ethylene glycol)-based macromonomers. Polym Chem 2019. [DOI: 10.1039/c9py00104b] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Polymerization of poly(ethylene glycol)-based macromonomers is a facile and versatile synthetic method to generate well-defined brush polymers.
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Affiliation(s)
- Xiaojin Zhang
- Engineering Research Center of Nano-Geomaterials of Ministry of Education
- Faculty of Materials Science and Chemistry
- China University of Geosciences
- Wuhan 430074
- China
| | - Yu Dai
- Engineering Research Center of Nano-Geomaterials of Ministry of Education
- Faculty of Materials Science and Chemistry
- China University of Geosciences
- Wuhan 430074
- China
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