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 a...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 coefficientμfor 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.展开更多
基金We are grateful to the support from Natural Science Foundation of Jiangsu Province(Grant No.BK20191289)the National Natural Science Foundation of China(Grant Nos.21838004,21606131,and 21676137)and the financial support from Instrument&EquipmentOpen Funding of Nanjing University of Science and Technology.The Swedish Foundation for Strategic Research(Grant No.EM16-0013)is also gratefully acknowledged for the financial support.
文摘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 coefficientμfor 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.
