A one-side hydrophilic polypropylene membrane prepared by plasma treatment

Abstract

The surface on one side of a hydrophobic polypropylene (PP) membrane was modified with a gaseous plasma of 60 W discharge power in the presence of ammonia gas at 0.9 Torr pressure. Results of contact angle measurements indicate that one side of the hydrophobic membrane was modified; it became hydrophilic while the other side remained hydrophobic. Data from ESCA (electron spectroscopy for chemical analysis; X-ray photoelectron spectroscopy) and ATR-IR (attenuated total reflectance infrared) spectral analysis showed that the hydrophilicity was mainly derived from the amino groups on the modified surface. The modified PP membrane was coupled to urease and used to construct a urea sensor, which gave electrode response time only half that of the conventional urea sensor. The enzyme electrode gave a potential change of 30 mV per decade of increase in analyte concentration. The response of this electrode remained stable during continuous use for up to 12 days.