A new method to prepare ionic-strength-sensitive membrane with improved anti-fouling property and blood compatibility is developed via in situ cross linked polymerization of sulfobetaine methacrylate (SBMA) in polyethersulfone (PES) solution and a liquid liquid phase separation technique. The modified membrane is characterized by attenuated total reflectance-Fourier transform infrared spectra (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), H-1 NMR measurements, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and water contact angle (WCA) measurement. The membrane with high PSBMA conLent shows obvious ionic-strength-sensitive property and ionic-strength reversibility, which are expressed by he fluxes of salt solutions. Meanwhile, with the increase of the PSBMA content. in he membrane, the anti-fouling properly and blood compatibility are considerably improved. (C) 2014 Elsevier B.V. All rights reserved.