Photografting Modification of PET Nucleopore Membranes

Abstract

PET nucleopore membranes were modified by photografting polymerization. The grafted membrane has a well-defined structure. Grafting polymerization is confined on the membrane surface; no graft occurs inside membrane pores. The grafted PAA was characterized with ESCA, and the morphology of grafted membranes was observed by SEM. The high monomer concentration, temperature and UV intensity is beneficial to the increase of grafting degree (D_g). BP as initiator has an optimized concentration due to the self-screening. Membrane surface was changed into hydrophilic via 10 sec. treatment. The competition of water affinity of membrane surface and swelling-cover effect of grafted layer result in the filtration rate of grafted membranes varied with the D_g. At low D_g, flux is larger than that of blank membrane; at high D_g, the swelled PAA chains on the membrane surface cover the membrane pores and thus the flux decreases dramatically even close to zero, whereas SEM shows that the membrane pores are still open in dry state.

Keywords:

• Photografting
• Nucleopore membranes
• Surface modification
• Grafting modification

Acknowledgments

This work was supported by Funds of the Ministry of Education of China for Doctoral Program (1999001005) and the Chinese State Outstanding Youth Foundation (20025415), and are gratefully acknowledged.