Silsesquioxanes-Based Nanolubricant Additives with High Thermal Stability, Superhydrophobicity, and Self-cleaning Properties

Nanoadditives are promising materials for long-envisioned next-generation lubricants to achieve excellent tribological performance and thermal stability. Here, an instigative and novel approach has been scrutinized to facilely prepare the nanolubricant additive. For this purpose, three synthetic strategies were designed for i) preparation of uniform-sized poly(methyl silsesquioxane) (PMSQ) nanoparticles, ii) hydrosilylation of the long carbon chain of ethyl 10-undecenoate and iii) modification of PMSQ nanoparticles with hydrosilylation product through a condensation reaction, in order to obtain long-carbon-chain grafted nanohybrids. The morphology, composition, and properties of these nanohybrids were confirmed by ¹H-NMR, FTIR, SEM, EDS, and TGA. The effects of different concentrations of unmodified and modified PMSQ nanoparticles on the tribological properties of silicone oil were discussed. In the comparison of unmodified PMSQ nanoparticles, the modified one performs very well to reduce the coefficient of friction and wear scar diameter at low concentration. The TGA results revealed the extraordinary thermal stability of these particles, as their weight loss was only 19% at 800 °C which is remarkably higher than other solid lubricant additives. In this research, we tried to fill the deficiency of thermally stable material in the field of heavy machinery and industry. In addition, the environment-friendly (fluorine-free), superhydrophobic and self-cleaning surface effect of modified PMSQ nanoparticles was also observed. These silsesquioxane-based nanohybrids having synergistic effects, advantageous scientific values, and promising application prospects are expected to be more useful with other longer carbon chains.