Biomimetic surface design for ultrahigh molecular weight polyethylene to improve the tribological properties

Abstract

Tribological problem is a major obstacle that limits the using of ultrahigh molecular weight polyethylene (UHMWPE) in industrial applications and orthopedic surgeries. Many efforts have been made to improve the tribological properties of UHMWPE, such as promoting the structure, morphology, and mechanical properties of the polymer. Inspired by the features of articular surface, micro-scaled texture is introduced to improve the tribological properties of UHMWPE using micro-imprint lithography. Friction and wear experiments are conducted on textured and untextured specimens using ring-on-disc test apparatus under water lubrication. The experimental results demonstrate that the micro-scaled surface texture can remarkably improve the tribological properties of UHMWPE. Friction force can be effectively reduced by selecting suitable dimple parameters. Compared with an untextured UHMWPE, the textured one with optimum parameters shows a reduction in the friction coefficient as much as 66.7–85.7% on different load–speed conditions. The optimized area density of surface textured UHMWPE ranges from 22.9% to 29.9%, which is obviously higher than that of stiff materials such as metals and ceramics. The textured UHMWPE with area density 29.9%, diameter 50 µm, and depth 15 µm presents a significant effect of wear resistance. The average wear depth of textured UHMWPE is 35.5% of that of untextured one.