Industrial Preparation of Self-Lubricating Polyurethane via Direct Fluorination with Gaseous Fluorine

Fluorination modification is an effective way to improve the friction property of a polymer; however, current preparation of fluorine-containing polymers is limited by the high cost and complex synthesis. Here, an industrial fluorination strategy with gaseous fluorine (F₂) to achieve fluorine enrichment on the surface of a polyurethane (PU) sheet was demonstrated. Benefiting from the high reactivity and strong diffusion of F₂ gas, the as-prepared PU sample was characterized by the rich fluorinated surface with the slightly fluorinated bulk. As a result, the fluorinated PU combined the excellent mechanical properties of pristine PU with the unique function of the fluorine-containing polymer, where the fluorinated surface may function as a robust lubricating layer, contributing to remarkable promotion of friction property while maintaining the mechanical strength unchanged. The friction coefficient decreased to 0.5 at the dry condition and 0.1 at the wet condition from the initial value of 1 and 0.45 for the pristine PU sample. The surface manipulation via direct fluorination offers great opportunities to tailor the friction property while keeping the mechanical strength unchanged.