HYDROPHILIZATION OF MICROPOROUS POLYPROPYLENE CELGARD(R) MEMBRANES BYTHE CHEMICAL MODIFICATION TECHNIQUE

Microporous hydrophobic polypropylene (PP) membranes (Celgard(R) 2400 and 2500) were modified by the chemical modification technique to impa rt permanent hydrophilicity. The modification was carried out in two s tages. In the first stage, the membranes were hydroxylated by treatmen t with aqueous potassium peroxydisulfate solution under a strong flow of nitrogen. In the second stage, the hydroxylated membranes were subj ected to grafting of acrylamide using cerric ammonium nitrate as an in itiator. Subsequently, acrylamide grafted PP membranes were partially hydrolyzed to have carboxyl functional groups at the membrane surfaces . Under given experimental conditions the grafting also took place wit hin the pores of the microporous structure of hydrophobic PP Celgard(R ) membranes. Modified membranes exhibited permanently wettable charact eristics by aqueous solutions and appeared translucent when immersed i n water. Contact angle measurements showed excellent wetting propertie s with water. In contrast to unmodified Celgard(R) membrane, the modif ied membranes exhibit water permeability even after repeated drying. M embranes were further characterized by FTIR and ESCA for the different types of functional groups. (C) 1996 John Wiley & Sons, Inc.