Surface modification ofrnPEN treated with ozonernand UV photooxidation

摘要

Poly(ethylene 2,6-naphthalate) (PEN) was treated with ozone in the absence of radiation and the results wererncompared with ultraviolet (UV) photooxidation using 253·7 and 184·9 nm radiations. The surface modification of therntop 2–5 nm was analyzed by X-ray photoelectron spectroscopy (XPS) for chemical changes. Higher saturation levelsrnof oxidation were achieved using UV photooxidation than ozonation. Both treatment methods increased thernamounts of C–O–C, C=O and O–C=O bondings while UV photooxidation also increased the concentration of thernanhydride/carbonate moieties on the surface. Atomic force microscopy detected smoother surfaces with increasingrntreatment time for both the treatments. The changes in functional groups and surface roughness with bothrntreatments contributed to an increase in hydrophilicity as determined by advancing water contact anglernmeasurements. A greater increase in hydrophilicity was observed for the UV photooxidized PEN samples. Initialrnresults showed a slight increase in hydrophilicity when acrylic acid was grafted onto ozone-treated PEN surfaces,rnalthough, the ester group in the PEN structure made it difficult to detect poly(acrylic acid) by XPS.