Phytic acid-based deep eutectic solvent: A sustainable and high-performance bio-derived lubricant additive for polyethylene glycol

A renewable bio-based phytic acid-based deep eutectic solvent (DES) was developed as a green lubricant additive. • DES addition improved PEG400 friction and wear performance under various conditions. • The lubrication mechanism of DES has been elucidated. Driven by the goals of sustainable development and environmental protection, this study aims to address the reliance of conventional lubricant additives on non-renewable petrochemical resources. To this end, a green deep eutectic solvent (DES) type lubricant additive was designed and prepared using renewable bio-based phytic acid (PA) as the raw material. The tribological performance of the DES in PEG400 under various testing parameters was evaluated using a reciprocating friction and wear tribometer (SRV). Findings indicate that the DES markedly enhances the friction-reducing and anti-wear performance of Polyethylene glycol 400 (PEG400) under various loads (50–300 N), a wide temperature range (25–150 °C), and multiple frequencies (5–45 Hz). When 0.25 wt% is added, the average coefficient of friction (ACOF) of PEG400 was reduced by up to 48.69%, the wear volume decreased by 97.68%. The lubrication mechanism of the PA-based DES was elucidated by analyzing the microstructure and chemical composition of the wear surfaces. It was found that the DES forms an in situ organic-inorganic hybrid composite lubricating film at the friction interface through chemical adsorption and tribochemical reactions, thereby delivering excellent lubrication performance. The work thus proposes a new direction for creating sustainable, high-performance lubricant additives. Download: Download high-res image (265KB) Download: Download full-size image