Ablation and water etching of plasma-treated polymers

Ablation and water etching of low-density polyethylene (LDPE), polytetrafluorethylene, polystyrene, and polyethyleneterephtalate (PET) modified by Ar plasma was studied. The amount of ablated and etched material was determined by gravimetry. The changes in polymer surface morphology were observed using atomic force microscopy, UV-Vis and FTIR spectroscopy. This was used for the determination of the chemical structure of modified polymers. Wettability of polymers modified in plasma and water etched was determined from contact angle measurement. It was found that under the plasma discharge the polymers are ablated and their surface morphology and roughness are changed dramatically. The plasma treatment leads to an increase in the concentration of conjugated double bonds. Dissolution of a thin surface layer of plasma-modified PET and LDPE during water etching was observed and preferential liberation of low-molecular weight segments was proved.