Wettability characteristics variation of PMMA by means of CO₂ laser generated surface patterns

CO₂ lasers can be seen to lend themselves to materials processing applications and have been used extensively in research and industry. This work investigated the surface modification of PMMA with a CO₂ laser in order to vary wettability characteristics. The wettability characteristics of the PMMA were modified by generating a number of patterns of various topography on the sample surfaces using a CO₂ laser. Through white light interferometry it was found that for all laser patterned samples the surface roughness had significantly increased by up to 3.1 μm. The chemical composition of selected samples were explored using X-ray photoelectron spectroscopy and found that the surface oxygen content had risen by approximately 4% At. By using a sessile drop device it was found that 50 μm dimensions gave rise to a more hydrophilic surface; whereas 100 μm dimensions gave rise to either no change or an increase in contact angle making the PMMA hydrophobic. This can be explained by the possibility of different wetting regimes taking place owed to the variation of topographies over the as-received and laser patterned samples.