Synthesis and temperature-sensitive lubrication behavior of PNIPAM microgels for titanium alloy

Abstract

Purpose This paper aims to offeri novel nano-additives polymer microgels to precisely improve the lubrication properties of titanium alloy under different temperatures. Design/methodology/approach The surfactant-free emulsion polymerization method was used to prepare Poly(N-isoprolylacrylamide) (PNIPAM) microgels. A ball-on-disk tribometer was applied to investigated the temperature-sensitive lubrication behavior of PNIPAM microgels. Findings The results show that the as-prepared microgels are ball-like nanoparticles with the size of 50–900 nm. In addition, potassium persulfate as initiator, complete mixing technic and high sodium dodecyl sulfate (SDS) concentration contribute to the formation of microgels with small size. The tribosystem shows a lower friction coefficient with the lubrication of PNIPAM microgels as aqueous solution additives when the temperature exceeding the critical temperature. Originality/value This work reports the temperature-sensitive lubrication of PNIPAM microgels. The critical temperature of PNIPAM microgels could be regulated by the addition of SDS in the solutions. This offers an effective and facile strategy for regulation of the critical temperature of smart microgels, which is helpful for the smart lubrication in the future.

Lubrication performance of GQDs@PNIPAM microgels for titanium alloys

“…From the TEM images in Figure 2, it could be seen that both PNIPAM and GQDs@PNIPAM microgels had similar spherical structures with uniform particle size distribution and good dispersion. The particle size of PNIPAM microgels was about 90 nm, which was reported in our previous work, 41 while the particle size of GQDs@PNIPAM microgels was about 70 nm. It showed that GQDs participated in the reaction during the preparation of GQDs@PNIPAM microgels, and affected the polymerisation of the long chains of the microgels, resulting in the smaller particle size of GQDs@PNIPAM microgels.…”

“…Although many investigations about the lubrication roles of both PNIPAM and GQDs have been reported, 40,41 there are no reports on the synergistic lubrication performance of PNIPAM and GQDs nanocomposites. In particularly, to the authors' best knowledge, there is no work on the lubrication of GQDs@ PNIPAM microgels for titanium alloy machining process.…”

Wound Microenvironment Self-Adjusting Hydrogels with Thermo-Sensitivity for Promoting Diabetic Wound Healing

“…Such bio-hydrogels can modulate and regulate feedback control of drug release. As a temperature-responsive polymer, Poly(N-isopropylacrylamide) (PNIPAM) has lower critical solution temperatures (LCST) that are extremely close to the human physiological temperature, about 32 • C [14,15]. When the ambient temperature is higher than the LCST, hydrogen bonds are formed between the isopropyl amide groups on the molecular chain of PNIPAM and the polymer contracts, releasing the drug and water for targeted release, which improves the drug utilization rate [16].…”