Surface Functionalization of Polyethylene Terephthalate Film and Membranes by Controlled Wet Chemistry: II. Reactivity Assays of Hydroxyl Chain Ends

Surface functionalization of polyethylene terephthalate film and track-etched microporous membranes was performed using organic synthesis at the solid–liquid interface. The hydroxyl chain ends, naturally occurring in the membranes or created by basic hydrolysis in the film, were activated by reaction withp-toluenesulfonyl chloride and then coupled to [4,5-3H]lysine used as a model of water-soluble bioactive molecules. The ratios of derivatization were determined by liquid scintillation counting of the radioactivity associated with the samples. The hydroxyl chain ends were further reacted with 4,4′-methylene di(phenyl isocyanate); the resulting surfaces equipped with sensitive isocyanate spacers were assayed as before using [4,5-3H]lysine. The ranges of derivatization were from 5 to 60 pmol of fixed amino acid per open surface unit (cm2). Some samples were also analyzed by X-ray photoelectron spectroscopy.