Improved interfacial bonding strength of laser TC4/UHMWPE joints via a hybrid surface pretreatment

Titanium alloys and ultra-high molecular weight polyethylene (UHMWPE) are extensively utilized in biomedical implants due to their biocompatibility. As a kind of non-polar polymer, UHMWPE exhibits low surface activity and hydrophobicity, hindering a strong bonding to titanium alloys. This study introduced a novel hybrid modification method aimed at improving the reliability of artificial joint prostheses with a hybrid structure of Ti-6Al-4V titanium alloy (TC4) and UHMWPE. Firstly, the introduction of polar groups on the UHMWPE surface using an ultraviolet (UV) lamp/ozone. Secondly, the textured grids were processed on the TC4 surface using laser processing. The two materials were laser joined via heat transfer mode with a TC4-on-UHMWPE configuration. The bonding interface and fracture were characterized and analyzed by scanning electron microscopy (SEM), energy spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), which indicated the formation of mechanical interlocking and the generation of new chemical bonds at the interface. The bonding mechanism at the joint interface was also confirmed by density functional theory (DFT) calculations. The bidirectionally modified TC4-UHMWPE hybrid structure obtained a maximum tensile shear of 1233 N, realizing joint strength matching. This provides a new solution for the joining of non-polar polymers to metals. It is also essential for the development of more durable and reliable biomedical implants and prostheses.