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Friction  2022, Vol. 10 Issue (2): 268-281    doi: 10.1007/s40544-021-0486-4
Research Article     
Probing the nanofriction of non-halogenated phosphonium- based ionic liquid additives in glycol ether oil on titanium surface
Xiuhua QIU1,Linghong LU2,Zhenyu QU1,Jiongtao LIAO1,Qi FAN1,Faiz Ullah SHAH3,Wenling ZHANG4,Rong AN1,*()
1 Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
2 State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing 211816, China
3 Chemistry of Interfaces, Lule? University of Technology, Lule? 97187, Sweden
4 Department of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
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Abstract  

The nanofrictional behavior of non-halogentated phosphonium-based ionic liquids (ILs) mixed with diethylene glycol dibutyl ether in the molar ratios of 1:10 and 1:70 was investigated on the titanium (Ti) substrate using atomic force microscopy (AFM). A significant reduction is observed in the friction coefficient μ for the IL-oil mixtures with a higher IL concentration (1:10, μ ~ 0.05), compared to that for the lower concentration 1:70 (μ ~ 0.1). AFM approaching force-distance curves and number density profiles for IL-oil mixtures with a higher concentration revealed that the IL preferred to accumulate at the surface forming IL-rich layered structures. The ordered IL-rich layers formed on the titanium surface facilitated the reduction of the nanoscale friction by preventing direct surface-to-surface contact. However, the ordered IL layers disappeared in the case of lower concentration, resulting in an incomplete boundary layers, because the ions were displaced by molecules of the oil during sliding and revealed to be less efficient in friction reduction.



Key wordsionic liquid      nanofriction      atomic force microscopy (AFM)      ordering      density     
Received: 10 August 2020      Published: 17 January 2022
Fund:  Natural Science Foundation of Jiangsu Province(BK20191289);National Natural Science Foundation of China(21838004);The Swedish Foundation for Strategic Research(EM16-0013)
Corresponding Authors: Rong AN     E-mail: ran@njust.edu.cn
About author: Xiuhua QIU. He received his bachelor degree in materials science in 2017 from Henan Polytechnic University, China. He joined Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, at Nanjing University of Science and Technology, as a master student since 2017. He is now focusing on the studies about the nanotribological behavior of ionic liquids.|Linghong LU. She received her master degree in engineering from Harbin Engineering University, China, in 2000, and Ph.D. degree in Science from Zhejiang University, China, in 2005. She joined the College of Chemical Engineering of Nanjing Tech University from 2005. Her current position is a professor. Her research areas cover molecular simulation, structural property of confined fluid, adsorption, separation, and electrode materials.|Zhenyu QU. He is a senior undergraduate student in Department of Materials Science and Engineering at Nanjing University of Science and Technology, China. His research interests include nanotribological properties of different functional materials and heterogeneously structured surfaces.|Jiongtao LIAO. He is a senior undergraduate student in Department of Materials Science and Engineering at Nanjing University of Science and Technology, China. His research interests include ionic liquids behavior at solid interfaces and nano-tribology.|Qi FAN. He is a senior undergraduate student in Department of Materials Science and Engineering at Nanjing University of Science and Technology, China. His research interests include the quantitative analysis of single molecular forces of charged surfaces with ionic liquids and lithium-sulfur batteries.|Faiz Ullah SHAH. He received his Ph.D. degree in Chemistry of Interfaces, Luleå University of Technology, Sweden, in 2011. He joined Chemistry of Interfaces, Luleå University of Technology, from 2011. His current position is an associate professor. His research areas cover the synthesis of ionic liquids and the applications, e.g., batteries, lubricants, and gas separation.|Wenling ZHANG. She received her Ph.D. degree from Inha University, Korea in 2015 and joined University of Alberta, Canada as a postdoc (2018-2019). She is currently a professor at the School of Mechanical Engineering, Nanjing University of Science and Technology. Her research interests focus on soft matters (electro/ magneto-rheological phenomena) and nanotribology (adhesion, friction, and lubrication).|Rong AN. She received her Ph.D. degree in chemical engineering from Nanjing Tech University, China, in 2013. Then she worked as a postdoc researcher in Chemical and Biomolecular Engineering at North Carolina State University from 2013 to 2015. She joined Herbert Gleiter Institute of Nanoscience, Department of Materials Science and Engineering, at Nanjing University of Science and Technology from 2015. Her current position is an associate professor. Her research interests include the nanotribology of ionic liquids at solid interfaces, liquid-solid interfacial phenomena, and gas separation, etc.
Cite this article:

Xiuhua QIU,Linghong LU,Zhenyu QU,Jiongtao LIAO,Qi FAN,Faiz Ullah SHAH,Wenling ZHANG,Rong AN. Probing the nanofriction of non-halogenated phosphonium- based ionic liquid additives in glycol ether oil on titanium surface. Friction, 2022, 10(2): 268-281.

URL:

http://friction.tsinghuajournals.com/10.1007/s40544-021-0486-4     OR     http://friction.tsinghuajournals.com/Y2022/V10/I2/268

Fig. 1 Structural illustration and abbreviations of [BOB]-, [BScB]-, [BMB]-, [DCA]-, [P4,4,4,8]+, [P6,6,6,14]+, as well as the base oil DEGDBE.
Fig. 2 AFM topographic images for (a) pristine bare Ti substrate and neat DEGDBE oil coated Ti, and (b-f) the IL-oil mixtures coated Ti (1:70, 1:10).
Fig. 3 High-resolution spectra of O 1s, P 2p, and B 1s + P 2s scans for [P6,6,6,14][BScB]-oil mixtures on Ti (1:70, 1:10).
Fig. 4 Comparison of ATR-FTIR spectra for the bare Ti substrate, neat oil, neat IL [P6,6,6,14][BScB], and [P6,6,6,14][BScB]-oil mixtures on Ti.
Fig. 5 Friction force measurements for (a) the bare Ti substrate and neat DEGDBE oil on Ti surface, (b) ILs-oil mixtures on Ti surface with varying molar ratio of the IL in the DEGDBE oil with silicon nitride AFM tip. The fitting slope in (a) and (b) is μ. The raw friction data has been listed in Fig. S4 and Table S1 in the ESM.
Molar ratio of IL to oil1:701:10
Bare Ti0.23 ± 0.001
Neat oil0.14 ± 0.005
[P6,6,6,14][BScB]0.11 ± 0.0010.058 ± 0.004
[P6,6,6,14][DCA]0.10 ± 0.0010.052 ± 0.001
[P6,6,6,14][BOB]0.14 ± 0.0010.060 ± 0.001
[P6,6,6,14][BMB]0.12 ± 0.0030.063 ± 0.002
[P4,4,4,8][BScB]0.10 ± 0.0030.056 ± 0.001
Table 1 Nanofriction coefficients of the bare Ti substrate, neat DEGDBE oil on Ti surface, and ILs-oil mixtures (1:70, 1:10) on the Ti surface.
Fig. 6 Representative approaching force-distance curves for ILs-oil mixtures (1:70 and 1:10) coated Ti surfaces with AFM colloidal probes. (a) [P6,6,6,14][BScB], and the left panel is an AFM glass colloidal probe approaching the liquid film of [P6,6,6,14][BScB]-oil mixture (1:70) on the Ti surface (A-D), the probe being retracted after contact (shown in Fig. S3 in the ESM). The inset is a borosilicate glass microsphere attached to a tipless Si3N4 cantilever with a dimension of 20 μm; (b) [P6,6,6,14][DCA]; (c) [P6,6,6,14][BOB]; (d) [P6,6,6,14][BMB]; and (e) [P4,4,4,8][BScB]. The blue and grey arrows correspond to two interfacial layers.
Fig. 7 Number density profiles of cations, anions, as well as the oil in [P6,6,6,14][BScB]-oil mixtures (1:10 molar ratio) confined between the bilayer graphene tip and rutile (110) surface at a slit pore width of 10.7 nm.
Fig. 8 Schematic illustration of the IL-oil mixtures (molar ratio of 1:70, 1:10) distributed at Ti interfaces. The thickness of the ordered IL layers (tL) is composed of dense and loose layers. tLD: the thickness of the near surface denser layer; tLL: the thickness of the upper slightly looser layer.
[1]   Holmberg K, Erdemir A. The impact of tribology on energy use and CO2 emission globally and in combustion engine and electric cars. Tribol Int 135: 389-396 (2019)
[2]   Zhou F, Liang Y, Liu W. Ionic liquid lubricants: Designed chemistry for engineering applications. Chem Soc Rev 38: 2590-2599 (2009)
[3]   Jones W R Jr, Jansen M J. Space tribology. In NASA Technical Report NASA-TM-209924, Ohio, USA, 2000: 1-11.
[4]   Tripathi M, Awaja F, Paolicelli G, Bartali R, Iacob E, Valeri S, Ryu S, Signetti S, Speranza G, Pugno N M. Tribological characteristics of few-layer graphene over Ni grain and interface boundaries. Nanoscale 8: 6646-6658 (2016)
[5]   Hayes R, Warr G G, Atkin R. Structure and nanostructure in ionic liquids. Chem Rev 115: 6357-6426 (2015)
[6]   Wang Y, Wang C, Zhang Y, Huo F, He H, Zhang S. Molecular insights into the regulatable interfacial property and flow behavior of confined ionic liquids in graphene nanochannels. Small 15: 1804508 (2019)
[7]   Zhang S, Zhang J, Zhang Y, Deng Y. Nanoconfined ionic liquids. Chem Rev 117: 6755-6833 (2017)
[8]   Zhou Y, Qu J. Ionic liquids as lubricant additives: a review. ACS Appl Mater Interfaces 9: 3209-3222 (2017)
[9]   Hjalmarsson N, Atkin R, Rutland M W. Is the boundary layer of an ionic liquid equally lubricating at higher temperature? Phys Chem Chem Phys 18: 9232-9239 (2016)
[10]   Hayes R, Imberti S, Warr G G, Atkin R. Amphiphilicity determines nanostructure in protic ionic liquids. Phys Chem Chem Phys 13: 3237-3247 (2011)
[11]   Ray A. Solvophobic interactions and micelle formation in structure forming nonaqueous solvents. Nature 231: 313-315 (1971)
[12]   Greaves T L, Weerawardena A, Krodkiewska I, Drummond C J. Protic ionic liquids: Physicochemical properties and behavior as amphiphile self-assembly solvents. J Phys Chem B 112: 896-905 (2008)
[13]   Triolo A, Russina O, Bleif H-J, Di Cola E. Nanoscale segregation in room temperature ionic liquids. J Phys Chem B 111: 4641-4644 (2007)
[14]   Fan M, Yang D, Wang X, Liu W, Fu H. Doss- based qails: As both neat lubricants and lubricant additives with excellent tribological properties and good detergency. Ind Eng Chem Res 53: 17952-17960 (2014)
[15]   Li H, Somers A E, Howlett P C, Rutland M W, Forsyth M, Atkin R. Addition of low concentrations of an ionic liquid to a base oil reduces friction over multiple length scales: A combined nano-and macrotribology investigation. Phys Chem Chem Phys 18: 6541-6547 (2016)
[16]   Taher M, Shah F U, Filippov A, De Baets P, Glavatskih S, Antzutkin O N. Halogen-free pyrrolidinium bis(mandelato) borate ionic liquids: Some physicochemical properties and lubrication performance as additives to polyethylene glycol. RSC Adv 4: 30617-30623 (2014)
[17]   Rohlmann P, Munavirov B, Furó I, Antzutkin O, Rutland M W, Glavatskih S. Non-halogenated ionic liquid dramatically enhances tribological performance of biodegradable oils. Front Chem 7: 98 (2019)
[18]   Cai M, Yu Q, Zhou F, Liu W. Physicochemistry aspects on frictional interfaces. Friction 5(4): 361-382 (2017)
[19]   Zhang J, Meng Y. Boundary lubrication by adsorption film. Friction 3(2): 115-147 (2015)
[20]   Meng Y, Xu J, Jin Z, Prakash B, Hu Y. A review of recent advances in tribology. Friction 8(2): 221-300 (2020)
[21]   Qu J, Bansal D G, Yu B, Howe J Y, Luo H, Dai S, Li H, Blau P J, Bunting B G, Mordukhovich G, Smolenski D J. Antiwear performance and mechanism of an oil-miscible ionic liquid as a lubricant additive. ACS Appl Mater Interfaces 4: 997-1002 (2012)
[22]   Pejakovi? V, Tomastik C, D?rr N, Kalin M. Influence of concentration and anion alkyl chain length on tribological properties of imidazolium sulfate ionic liquids as additives to glycerol in steel-steel contact lubrication. Tribol Int 97: 234-243 (2016)
[23]   Jiang D, Hu L, Feng D. Tribological properties of crown- type phosphate ionic liquids as lubricating additives in rapeseed oils. Lubr Sci 25: 195-207 (2013)
[24]   An R, Zhou G, Zhu Y, Zhu W, Huang L, Shah F U. Friction of ionic liquid-glycol ether mixtures at titanium interfaces: negative load dependence. Adv Mater Interfaces 5: 1800263 (2018)
[25]   Nicholls M A, Do T, Norton P R, Kasrai M, Bancroft G M. Review of the lubrication of metallic surfaces by zinc dialkyl- dithiophosphates. Tribol Int 38: 15-39 (2005)
[26]   Suzuki A, Shinka Y, Masuko M. Tribological characteristics of imidazolium-based room temperature ionic liquids under high vacuum. Tribol Lett 27: 307-313 (2007)
[27]   Kondo Y, Yagi S, Koyama T, Tsuboi R, Sasaki S. Lubricity and corrosiveness of ionic liquids for steel-on-steel sliding contacts. Proc Inst Mech Eng Part J: J Eng Tribol 226: 991-1006 (2012)
[28]   Ye C, Liu W, Chen Y, Yu L. Room-temperature ionic liquids: A novel versatile lubricant. Chem Commun 21: 2244-2245 (2001)
[29]   Minami I. Ionic liquids in tribology. Molecules 14: 2286-2305 (2009)
[30]   Swatloski R P, Holbrey J D, Rogers R D. Ionic liquids are not always green: Hydrolysis of 1-butyl-3-methylimidazolium hexafluorophosphate. Green Chem 5: 361-363 (2003)
[31]   Wasserscheid P, Van Hal R, Bosmann A. 1-n-butyl-3- methylimidazolium (bmim) octylsulfate—An even ‘greener’ ionic liquid. Green Chem 4: 400-404 (2002)
[32]   Pattee H E, Monroe R E. Adhesion in the space environment. In NASA Technical Report NASA-TM-X59395, Alabama, USA, 1966: 1-109.
[33]   Zhang X Y, Hua Y X, Xu C Y, Zhang Q B, Cong X B, Xu N. Direct electrochemical reduction of titanium dioxide in Lewis basic AlCl3-1-butyl-3-methylimidizolium ionic liquid. Electrochim Acta 56: 8530-8533 (2011)
[34]   Flower H M. A moving oxygen story. Nature 407: 305-306 (2000)
[35]   Li H, Somers A E, Rutland M W, Howlett P C, Atkin R. Combined nano-and macrotribology studies of titania lubrication using the oil-ionic liquid mixtures. ACS Sustain Chem Eng 4: 5005-5012 (2016)
[36]   Liu X, Chu P K, Ding C. Surface modification of titanium, titanium alloys, and related materials for biomedical applications. Mat Sci Eng R: 47: 49-121 (2004)
[37]   Kaur S, Ghadirinejad K, H. Oskouei R. An overview on the tribological performance of titanium alloys with surface modifications for biomedical applications. Lubricants 7: 65-79 (2019)
[38]   Li H, Endres F, Atkin R. Effect of alkyl chain length and anion species on the interfacial nanostructure of ionic liquids at the Au (111)-ionic liquid interface as a function of potential. Phys Chem Chem Phys 15: 14624-14633 (2013)
[39]   Shah F U, Glavatskih S, Macfarlane D R, Somers A, Forsyth M, Antzutkin O N. Novel halogen-free chelated orthoborate-phosphonium ionic liquids: Synthesis and tribophysical properties. Phys Chem Chem Phys 13: 12865-12873 (2011)
[40]   Liu W, Bonin K, Guthold M. Easy and direct method for calibrating atomic force microscopy lateral force measurements. Rev Sci Instrum 78: 063707 (2007)
[41]   An R, Qiu X, Shah F U, Riehemann K, Fuchs H. Controlling the nanoscale friction by layered ionic liquid films. Phys Chem Chem Phys 22:14941-14952 (2020)
[42]   Buettner K M, Valentine A M. Bioinorganic chemistry of titanium. Chem Rev 112: 1863-1881 (2012)
[43]   Wang D H, Hu Y, Zhao J J, Zeng L L, Tao X M, Chen W. Holey reduced graphene oxide nanosheets for high performance room temperature gas sensing. J Mater Chem A 2: 17415-17420 (2014)
[44]   Nasybulin E, Xu W, Engelhard M H, Nie Z, Burton S D, Cosimbescu L, Gross M E, Zhang J-G. Effects of electrolyte salts on the performance of Li-O2 batteries. J Phys Chem C 117: 2635-2645 (2013)
[45]   Ozturk B, De-Luna-Bugallo A, Panaitescu E, Chiaramonti A N, Liu F, Vargas A, Jiang X, Kharche N, Yavuzcetin O, Alnaji M, Ford M J, Lok J, Zhao Y, King N, Dhar N K, Dubey M, Nayak S K, Sridhar S, Kar S. Atomically thin layers of B-N-C-O with tunable composition. Sci Adv 1: e1500094 (2015)
[46]   Hu J, Diao H, Luo W, Song Y-F. Dawson-type polyoxomolybdate anions (P2Mo18O626-) captured by ionic liquid on graphene oxide as high-capacity anode material for lithium-ion batteries. Chem-Eur J 23: 8729-8735 (2017)
[47]   Peng B, Xu Y, Liu K, Wang X, Mulder F M. High-performance and low-cost sodium-ion anode based on a facile black phosphorus-carbon nanocomposite. ChemElectroChem 4: 2140-2144 (2017)
[48]   Armelao L, Barreca D, Bottaro G, Canevali C, Morazzoni F, Scotti R, Tondello E. Boron and phosphorus quantification in sol-gel BPSG glasses by XPS. Surf Sci Spectra 10: 40-46 (2003)
[49]   Mishra A, Sahoo R K, Singh S K, Mishra B K. Synthesis of low carbon boron carbide powder using a minimal time processing route: thermal plasma. J Asian Ceram Soc 3: 373-376 (2015)
[50]   Shah F U, Gnezdilov O I, Filippov A. Ion dynamics in halogen-free phosphonium bis(salicylato)borate ionic liquid electrolytes for lithium-ion batteries. Phys Chem Chem Phys 19: 16721-16730 (2017)
[51]   Logacheva N M, Baulin V E, Tsivadze A Y, Pyatova E N, Ivanova I S, Velikodny Y A, Chernyshev V V. Ni(II), Co(II), Cu(II), Zn(II) and Na(I) complexes of a hybrid ligand 4′-(4′″- benzo-15-crown-5)-methyloxy-2,2′:6′,2″-terpyridine. Dalton Trans: 2482-2489 (2009)
[52]   Gusain R, Singh R, Sivakumar K L N, Khatri O P. Halogen-free imidazolium/ammonium-bis(salicylato)borate ionic liquids as high performance lubricant additives. RSC Adv 4: 1293-1301 (2014)
[53]   Bakshi P S, Gusain R, Khatri O P. Microtribological properties of a spin-coated thin film of 1-butyl-3- (propyltrimethoxysilane)imidazolium bis(mandelato)borate ionic liquid. RSC Adv 6: 78296-78302 (2016)
[54]   Quignon B, Pilkington G A, Thormann E, Claesson P M, Ashfold M N R, Mattia D, Leese H, Davis S A, Briscoe W H. Sustained frictional instabilities on nanodomed surfaces: Stick-slip amplitude coefficient. ACS Nano 7: 10850-10862 (2013)
[55]   Smith A M, Lovelock K R, Gosvami N N, Welton T, Perkin S. Quantized friction across ionic liquid thin films. Phys Chem Chem Phys 15: 15317-15320 (2013)
[56]   Leng Y, Jiang S. Dynamic simulations of adhesion and friction in chemical force microscopy. J Am Chem Soc 124: 11764-11770 (2002)
[57]   Pethica J B, Oliver W C. Tip surface interactions in stm and afm. Phys Scr 1987: 61-66 (1987)
[58]   Robinson B J, Kay N D, Kolosov O V. Nanoscale interfacial interactions of graphene with polar and nonpolar liquids. Langmuir 29: 7735-7742 (2013)
[59]   Tambe N S, Bhushan B. Identifying materials with low friction and adhesion for nanotechnology applications. Appl Phys Lett 86: 061906 (2005)
[60]   Bhushan B, LaTorre C, Wei G. In Springer handbook of nanotechnology. Bhushan, B, Ed. Berlin: Springer, 2007: 1276-1280.
[61]   Smith J A, Werzer O, Webber G B, Warr G G, Atkin R. Surprising particle stability and rapid sedimentation rates in an ionic liquid. J Phys Chem Lett 1: 64-68 (2010)
[62]   Hayes R, Warr G G, Atkin R. At the interface: solvation and designing ionic liquids. Phys Chem Chem Phys 12: 1709-1723 (2010)
[63]   Hamilton W A, Porcar L, Butler P D, Warr G G. Local membrane ordering of sponge phases at a solid-solution interface. J Chem Phys 116: 8533-8546 (2002)
[64]   Antelmi D A, Kékicheff P, Richetti P. The confinement- induced sponge to lamellar phase transition. Langmuir 15: 7774-7788 (1999)
[65]   Dragoni D, Manini N, Ballone P. Interfacial layering of a room-temperature ionic liquid thin film on mica: a computational investigation. Chemphyschem 13: 1772-1780 (2012)
[66]   Dyatkin B, Osti N, Zhang Y, Wang H-W, Mamontov E, Heller W T, Zhang P, Rother G, Cummings P, Wesolowski D J, Gogotsi Y. Ionic liquid structure, dynamics, and electrosorption in carbon electrodes with bimodal pores and heterogeneous surfaces. Carbon 129: 104-118 (2018)
[67]   Alibalazadeh M, Foroutan M. Specific distributions of anions and cations of an ionic liquid through confinement between graphene sheets. J Mol Model 21: 168 (2015)
[68]   Comtet J, Niguès A, Kaiser V, Coasne B, Bocquet L, Siria A. Nanoscale capillary freezing of ionic liquids confined between metallic interfaces and the role of electronic screening. Nat Mater 16: 634-639 (2017)
[69]   Dai Z, You Y, Zhu Y, Wang S, Zhu W, Lu X. Atomistic insights into the layered microstructure and time-dependent stability of [BMIM][PF6] confined within the meso-slit of carbon. J Phys Chem B 123: 6857-6869 (2019)
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