Grafting glutamic acid to a polyethylene terephthalate (PET) film treated with NH₃ plasma

Polyethylene terephthalate (PET) surfaces have been treated with NH₃ plasma, and subsequently grafted with glutamic acid using glutaraldehyde as crosslinker. The extent of surface modification of the PET films was investigated by contact angle measurements, ATR-FTIR, XPS spectra and activated partial thromboplastin time (APTT) measurements. The properties of the films after treatment with NH₃ alone were compared with those obtained after subsequent grafting with glutamic acid. It was found that the former are superior to the latter, and the blood compatibility was best when the power used was 70 W. The APTT times of the NH₃-treated film and the grafted film were respectively 5.9 s and 3.2 s longer than that of the untreated film.