In situ polymerised KH570-OH-BNNS/PAS composite emulsion achieves superior lubricity and load-bearing capacity

Conventional emulsion lubricants suffer from issues such as oil film rupture under high loads, poor lubrication stability and insufficient load-carrying capacity. To address these issues, this study developed an acrylic polymer emulsion (PAS) with a simple composition and KH570-modified hydroxylated boron nitride nanosheets (KH570-OH-BNNS), which were used to prepare a nanocomposite emulsion lubricant via in situ polymerisation. The resulting emulsion lubricant exhibits excellent stability, lubricity and load-carrying capacity. Under a test load of 294 N, a minimum coefficient of friction of 0.047 was achieved, representing a reduction of 85.6% compared with the base lubricant. The wear rate was as low as 1.03 × 10^-9 mm³ N^-1 m^-1, whilst the maximum anti-seize load (P_B) reached 1579 N. The lubrication mechanism indicates a synergistic effect between the polymer matrix and the modified boron nitride nanosheets at the friction interface, forming a dense organic-inorganic lubricating film that effectively prevents direct contact between steel surfaces, thereby exhibiting excellent tribological performance. This study provides a new strategy for the design of high-performance water-based emulsified lubricants and expands their potential applications in the field of lubrication.