Engineering a superamphiphilic surface for enhanced interfacial bonding in metal-polymer hybrid structure

Abstract

Insufficient wetting of polymer due to its poor compatibility with metals leads to non-intimate interfacial mutual contact during the thermal-direct bonding process, thus hindering the establishment of effective mechanical interlocking and substantial chemical bonding at the interface, resulting in deficient performance of metal-polymer hybrid structures. To achieve high-quality bonding between non-polar ultra-high molecular weight polyethylene (UHMWPE) and Ti6Al4V titanium alloy (TC4) for the application of artificial joint prostheses, this study innovatively engineered a superamphiphilic (simultaneously superhydrophilic and superlipophilic) TC4 surface, which was achieved through a morphology-chemistry dual regulation strategy. This pretreatment strategy aimed at improving the interfacial compatibility between in-situ oxidized UHMWPE and TC4 and ensuring intimate contact between these two materials during thermal-direct bonding, thus facilitating chemical reactions and mechanical interlocking at the interface. Defect-free and ultra-high-performance TC4-UHMWPE hybrid joints were successfully obtained via friction spot joining (FSpJ) with the lap shear strength reaching 18.05 MPa (higher than all those similar hybrid joints reported in existing literature) and the fracture was confined to the UHMWPE matrix, effectively avoiding interfacial failure. The formation of chemical bonds in the form of COTi at TC4/UHMWPE interface was solidly confirmed based on X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) analyses. This research presents a compelling strategy for improving interfacial compatibility between polymer and metal for thermal-direct bonding, to overcome the general difficulties in achieving effective interfacial bonding between these two categories of materials with significantly different physiochemical properties.