Hydration Lubrication Applicable to Artificial Joints through Polyelectrolyte-Embedded Modification on UHMWPE

Abstract

Hydration lubrication by the hydrated surface-grafted macromolecules covering the joint cartilage is crucial for the proper functioning of natural synovial joints. However, when considering artificial replacements, similar surface-grafted polymers on artificial materials are usually insufficient for the long-term lubrication due to lack of stability and durability. In this work, an overall material modification through embedding polyelectrolyte brushes was performed for prolonged lifetime. Method-wise, hydrophilic monomer 3-sulfopropyl methacrylate potassium salt (SPMK) was grafted onto ultrahigh molecular weight polyethylene (UHMWPE) powders through photoinduced radical graft polymerization, followed by hot-press forming of the modified powders to afford homogeneous modified material. Trials revealed significantly increased surface wettability and negative charge density, giving rise to strong hydration lubrication that led to a stable and low friction coefficient of 0.009, and an ultralow wear rate of 9.1 × 10–8 mm3 (N m)−1 under physiological conditions, which could be consistently maintained even after the surface was sheared off with polishing equipment. This overall material modification on UHMWPE through polyelectrolyte embedment, applied to obtain long-lasting, highly lubricated materials, therefore presents a promising method for the preparation of artificial joints.

Boosting UHMWPE Self-Lubricating Performance via Embedding Porous Cobalt-Based Zeolitic Imidazolate Framework Oil-Nanocontainers

“…In Figure a, the COF of pure UHMWPE increases gradually to 0.12 at the first 1 h, consistent with that in Figure a. Meanwhile, after that, the COF still keeps increasing evidently over time and no stable period appears until after 5 h testing, which is also revealed by the previous literature . However, after embedding PAO6@ZIF-67, the 10% PAO6@ZIF-67-reinforced UHMWPE can always keep a relatively low COF of ∼0.03, and no obvious attenuation was observed even after 5 h friction testing, suggesting the giant improvement of UHMWPE in friction lifetime after embedding PAO6@ZIF-67 oil-nanocontainers.…”

“…Meanwhile, after that, the COF still keeps increasing evidently over time and no stable period appears until after 5 h testing, which is also revealed by the previous literature. 21 However, after embedding PAO6@ ZIF-67, the 10% PAO6@ZIF-67-reinforced UHMWPE can always keep a relatively low COF of ∼0.03, and no obvious attenuation was observed even after 5 h friction testing, suggesting the giant improvement of UHMWPE in friction lifetime after embedding PAO6@ZIF-67 oil-nanocontainers. Furthermore, the 10% PAO6@ZIF-67-reinforced UHMWPE still keeps the excellent self-lubricating performance after repeated testing (Figure S3), indicating the good repeatability of PAO6@ZIF-67-reinforced UHMWPE.…”

Construction and tribological properties of poly acrylic acid‐poly(3‐(methacryloylamino)propyl) dimethyl(3‐sulfopropyl)ammonium hydroxide hydrogel coatings embedded with SiO2 nanoparticles on Ti6Al4V substrate

“…Nanoparticles embedded in the hydrogel network can effectively carry normal loads. Based on the hydration lubrication mechanism, negatively charged PAA polymer molecules on the surface of SiO 2 trap surrounding the counterions to generate load‐bearing osmotic pressure, thereby effectively resisting applied normal load 69,70 . Therefore, the introduction of polymer brushes on SiO 2 enhances the mechanical strength and excellent anti‐wear properties of polymer hydrogel.…”

Tribological Behavior of Sulfonated Polyether Ether Ketone with Three Different Chemical Structures under Water Lubrication

“…The Si 3 N 4 balls (diameter = 10 mm) were employed as friction pair materials. The Si 3 N 4 ball exhibits a negative surface charge, thereby facilitating hydration lubrication [34][35][36]. During the tests, the specimens were securely attached to a disc rotated by an electric motor, and "pointsurface" contact was made with the Si 3 N 4 ball fixed to the force sensors (Figure 1c).…”