2 research outputs found
DOSS<sup>–</sup> Based QAILs: As Both Neat Lubricants and Lubricant Additives with Excellent Tribological Properties and Good Detergency
DOSS<sup>–</sup> (dioctyl sulfosuccinate) based quaternary
ammonium ionic liquids (QAILs) were synthesized and used as both neat
lubricants and lubricant additives. The influence of structure on
their miscibility, thermal stability, and tribological property was
discussed. These QAILs are low cost as compared with conventional
halogen-containing ionic liquids (ILs). They are noncorrosive and
hydrolysis stable because of their halogen-free characteristics. The
tribological properties of these QAILs as neat lubricants for steel/steel
and steel/copper contacts are found to be better than conventional
halogen-containing ILs 1-butyl-3-methylimidazolium bisÂ(trifluoromethylsulfonyl)Âimide
(L-F104) and far better than traditional synthetic lubricant poly-α-olefin
(PAO). Moreover, oil-soluble ILs were obtained by properly adjusting
the chain length and cation asymmetry of these QAILs, which can be
easily dissolved in nonpolar synthetic-oil PAO. They are found to
be effective lubricant additives for improving the friction-reducing
and antiwear properties of PAO. It is a great advantage as compared
with conventional ILs, which have extremely low solubility in PAO
and are difficult to be used as lubricant additives for this kind
of base oil. Furthermore, the coking test results indicated that the
synthesized QAILs have high deterging ability when used as lubricant
additives for PAO. Thus, they can restrain carbonaceous deposition
as well as oil sludge and varnish formation on the metal contacts
during the sliding process. They can also disperse, loosen, and remove
the already formed harmful substances and keep the metal contacts
clean. The present work may make obvious progress toward preparing
low cost, noncorrosive, and environmentally benign IL lubricants in
lubrication engineering
Magnetization Dynamics Changes of Dysprosium(III) Single-Ion Magnets Associated with Guest Molecules
Two DyÂ(III) single-ion magnets with
a trigonal dodecahedron (<i>D</i><sub>2<i>d</i></sub>) for <b>1</b> and an approximately square-antiprismatic
(SAP, <i>D</i><sub>4<i>d</i></sub>) N<sub>2</sub>O<sub>6</sub> coordination environment for <b>2</b>, formulated
as [DyÂ(Phen)Â(tfmb)<sub>3</sub>] (<b>1</b>) and [DyÂ(Phen)Â(tfmb)<sub>3</sub>]·0.5Â(1,4-dioxane) (<b>2</b>) (tfmb = 4,4,4-trifluoro-1-(4-methylphenyl)-1,3-butanedione,
Phen = 1,10-phenanthroline), were obtained. Therein, complex <b>1</b> was transformed to <b>2</b> in 1,4-dioxane solution.
Structural analysis shows that complexes <b>1</b> and <b>2</b> have differing local symmetry of DyÂ(III) ions. Magnetic
studies indicate that the barrier heights (Δ<i>E</i>/<i>k</i><sub>B</sub>) of <b>1</b> and <b>2</b> are 63.56 and 102.82 K under zero dc field as well as 118.50 and
164.55 K under 1200 Oe dc field, respectively. Based on the frequency
dependencies of the ac susceptibilities, the effective barriers (Δ<i>E</i>/<i>k</i><sub>B</sub>) and the pre-exponential
factors (τ<sub>0</sub>) are 67.05 K and 4.57 × 10<sup>–6</sup> s for <b>1</b> and 95.88 K and 2.39 × 10<sup>–7</sup> s for <b>2</b> under zero dc field. The present work illustrates
that guest-determined notable structure change results in different
barrier heights