Surface Activation of Poly(methyl methacrylate) via Remote Atmospheric Pressure Plasma

An atmospheric pressure oxygen and helium plasma was used to activate the surface of poly(methyl methacrylate) (PMMA). The plasma physics and chemistry was investigated by numerical modeling. It was shown that as the electron density of the plasma increased from 3 × 10 10 to 1 × 10 12 cm −3 , the concentration of O atoms and metastable oxygen molecules ( 1 Δ g ) in the afterglow increased from 6 × 10 15 to 1 × 10 17 cm −3 . Exposing PMMA to the afterglow for times between 0 and 30 s led to a 35° ± 3° decrease in water contact angle, and a ten‐fold increase in bond strength to several adhesives. X‐ray photoelectron spectroscopy of the polymer revealed that after treatment, the surface carbon attributable to the methyl pendant groups decreased 5%, while that due to carboxyl acid groups increased 7%. The numerical modeling of the afterglow and experimental results indicate that oxygen atoms generated in the plasma oxidize the polymer chains. magnified image