EFFECT OF SURFACE TEXTURING ON MECHANICAL DURABILITY OF POLYMERS UNDER PHYSIOLOGICAL ENVIRONMENT

Biomedical polymers, such as high-density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE), are extensively used in prosthetic and implant applications due to their biocompatibility, mechanical strength, and versatility. These polymers are critical for applications like joint replacements and non-load-bearing implants, however their long-term durability in physiological environments can be compromised by moisture absorption, which can lead to degradation in mechanical performance. This study explores the influence of micro-scale surface texturing on the hydrophobic properties, moisture resistance, and long-term mechanical performance under prolonged exposure to physiological environment of HDPE and UHMWPE. Square, cylindrical, and hemispherical textures as protrusions or cavities with various sizes are introduced on HDPE and UHMWPE surfaces. Hydrophobicity was quantified via contact angles, revealing substantial enhancements of up to 52.2% for HDPE and 55.8% for UHMWPE with the introduction of surface micro-textures. The improvement in hydrophobicity delays the moisture absorption in HDPE, however, shows negligible effect on UHMWPE. This difference in moisture absorption is attributed to the structural difference in HDPE and UHMWPE. Uniaxial tensile testing under prolonged exposure to physiological environment shows that surface texturing help preserving mechanical durability. However, surface texturing affects the large molecular motions influenced by the moisture intake more significantly than the small molecular movements. These findings underscore surface texturing as a viable approach to improve mechanical durability of biomedical polymers exposed to physiological environments.