On optimizing wettability, surface roughness and swelling behaviour of laser-polished 3D-printed PETG polymer for bio-medical implants

The laser post-processing of 3D-printed polymers has gained considerable attention of many researchers in the field of tissue engineering and biomedical implant applications. Among several polymers, polyethylene terephthalate glycol (PETG) is a preferred material due to its biocompatibility, toughness and corrosion resistance. However, the wettability and swelling behaviour of laser surface polished PETG implants in contact with buffer solutions that mimic body fluids remains unexplored. This paper aims to investigate the effect of infill density (50 %, 60 %, 70 %, 80 %), laser power (1, 2, 3, 4 W), scanning speed (300 mm/s, 500 mm/s, 700 mm/s, 900 mm/s), and line spacing (0.01 mm, 0.04 mm, 0.08 mm, 0.12 mm) on surface roughness, wettability and swelling ratio of PETG specimens impregnated in phosphate, acetate and borate buffer solutions. The surfaces were characterised using a scanning electron microscope. Response Surface Methodology (RSM) was adopted to develop regression models and achieve optimal conditions of printing and laser parameters. The multi-objective optimisation predicted optimal infill density of 77.87 %, 554.54 mm/s scanning speed, 2.6 W laser power and 0.011 mm line spacing at the overall composite desirability of 0.876.