Synthesis and Lubrication of Phosphorylcholine Derivative

The monomer of phosphorylcholine derivative, O-(5-(2-methacryloxy) −3, 3-dimethyl-3-azapentyl)-O'-(ω-hydroxy-octyl)- phosphate quaternary ammonium salt, was designed and synthesized successfully. It was characterized by the spectra of 1H NMR and Mass spectra (ESI+), and every signal was assigned. Then the lubricating characteristics of the phosphorylcholine derivative were investigated on the tribological setup of ball-on-flat. The Ultra-High Molecular Weight Polyethylene (UHMWPE) flat was rotated against a stainless steel ball with 6 mm diameter. The load was 2.3 N, which corresponded to a maximal Hertz contact pressure of 29 MPa. Water, phosphorylcholine derivative, and Acrylic Acid (AA) solution were used as lubricants, respectively. Compared with AA, the phosphorylcholine derivative shows significant lubrication. It can be strongly hydrated under water due to the charged segment in chemical structure. The thick water layers within the chains serves as boundary lubricants, and this is thought to be the molecular origins of lubricating behavior.