Generic parameters governing the wettability characteristics of laser-modified nylon 6,6

Wettability is an interesting subject which spans any discipline that takes into account any form of adhesion. As such, it is imperative to identify generic parameters that govern the wetting nature of materials. This paper details the use of CO₂ and KrF excimer lasers to modify the surface of nylon 6,6 in order to modulate the wettability characteristics. White light interferometery allowed one to establish that the surface roughness (Ra) was dramatically increased by up to 4.5 uμm in comparison to the as-received sample. Using a sessile drop device it was determined for all samples that the polar component had a strong inverse relationship with the contact angle, θ. For the patterned samples an increase in θ indicated the likely formation of a mixed-state wetting regime and highlighted the significant influence of surface topography on θ. X-ray photoelectron spectroscopy determined that the surface oxygen content had increased by up to 5.7 %at. for all samples. Due to the highly modulated nature of θ over all samples it was concluded that surface oxygen content was not a dominant parameter; whereas the polar component and surface pattern were the most dominant parameters governing the wettability characteristics of the laser-surface-modified nylon 6,6.