SUMMARY In-situ attenuated total reflection (ATR)-FTIR spectroscopy was used to monitor the consecutively alternating adsorption of polyethylenimine (PEI) and poly(acry1ic acid) (PAC) onto both Si crystals (SiO) and COz plasma-treated polypropylene (PP) films. The vibration bands v,(COO-) and v(C=O) of PAC are diagnostic for the polyelectrolyte layer build-up and sensitive to protonation changes. Human serum albumine (HSA) adsorption experiments revealed a strong decrease of fouling for the PP films, which were modified with polyelectrolyte multilayers, in comparison to the unmodified ones.
SYNOPSISMicroporous hydrophobic polypropylene (PP) membranes (Celgard@ 2400 and 2500) were modified by the chemical modification technique to impart permanent hydrophilicity. The modification was carried out in two stages. In the first stage, the membranes were hydroxylated by treatment with aqueous potassium peroxydisulfate solution under a strong flow of nitrogen. In the second stage, the hydroxylated membranes were subjected to grafting of acrylamide using cerric ammonium nitrate as an initiator. 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 within the pores of the microporous structure of hydrophobic PP Celgard@ membranes. Modified membranes exhibited permanently wettable characteristics by aqueous solutions and appeared translucent when immersed in water. Contact angle measurements showed excellent wetting properties with water. In contrast to unmodified Celgard@ membrane, the modified membranes exhibit water permeability even after repeated drying.
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