Fabrication of Thermally Stable Polysulfone Microcapsules Containing [EMIm][NTf₂] Ionic Liquid for Enhancement of In Situ Self‐Lubrication Effect of Epoxy

Abstract

Microcapsules containing an ionic liquid (IL) are potential candidate materials for preparing in situ self‐lubricating composites with excellent tribological properties. 1‐ethyl‐3‐methylimidazolium bis[(trifluoromethyl) sulfonyl]imide ([EMIm]NTf2) IL encapsulated polysulphone microcapsules are synthesized. The mean diameter and wall thickness are about 128 μm and 10 μm, respectively. Microcapsules have excellent thermal stability, with a thermal degradation onset temperature of 440 °C compared to traditional lubricants‐loaded microcapsules. In situ self‐lubricating composites are prepared by incorporating the IL‐encapsulated microcapsules into epoxy matrix. When the concentration of the IL microcapsules is 20 wt%, the frictional coefficient and specific wear rate of composites are reduced by 66.7% and 64.9% under low sliding velocity and middling applied load conditions, respectively, as compared to the neat epoxy. The tribological behavior of the self‐lubricating composites is further assessed in different applied load and sliding velocity conditions. The in situ self‐lubricating mechanism of composites is proposed.

Preparation and application of polysulfone microcapsules containing tung oil in self-healing and self-lubricating epoxy coating

“…Figure 4 shows the FTIR spectra of the tung oil-loaded microcapsules, PSF and tung oil. Microcapsules spectra shows characteristic peeks of PSF at: ~1488 and ~1587 cm -1 (C=C aromatic rings stretching vibration), ~1322 and ~1294 cm -1 (O=S=O asymmetric stretching vibration), ~1239 cm -1 (C-O-C stretching vibration) [37] . The spectrum of microcapsules also shown the characteristic peeks of tung oil at: ~3012 cm -1 (=C-H stretching vibration), ~2927 and ~2855 cm -1 (-C-H stretching vibration), ~1745 cm -1 (C=O stretching vibration), ~725 cm -1 (-(CH 2 ) n -(n ≥ 4) bending vibration), FTIR curves confirm encapsulation of tung oil in the PSF particles.…”

Material encapsulation in poly(methyl methacrylate) shell: A review

“…Various polymers and inorganic materials can be used as capsule shell including poly(styrene), poly(urethane), poly(melamine formaldehyde), poly(urea), poly(urea formaldehyde), poly(melamine–urea–formaldehyde), poly(methyl methacrylate) (PMMA), poly(vinyl pyrrolidone), poly(sulfone), silica, titanium dioxide, calcium carbonate, and so forth. The choosing the appropriate capsule shell material is essentially affected by the nature of core material and its application after encapsulation .…”

Ultralow Tribological Properties of Polymer Composites Containing [BMIm]PF6‐Loaded Multilayer Wall Microcapsule

“…It was considered that the microcapsule ruptures were accompanied by [BMIm]PF 6 flowing out in the friction process, and then an effectively boundary lubricant film formed on the friction surface to prevent direct contact between the resin matrix and the counterface. Moreover, during the process of sliding friction, low energy electrons are emitted from the tiny contact convex points on the metal counterface and positive charges are formed due to the electrostatic attraction . The anion in bipolar [BMIm]PF 6 is easily absorbed at the positive charge sites on the counterface, which makes the lubricating films attach more firmly to the contact surface, thereby more effectively improving the tribological properties.…”

“…Various lubricants have been microencapsulated, including lubricant oil, paraffin, wax, diisocyanate, and ionic liquid . In addition to reducing friction and wear, lubricating oils are required to cool the rubbing surfaces that are heated due to friction.…”