Fabrication of N-halamine polymer/Ag NPs composites and CNT containing reverse osmosis membrane having antibacterial property

Abstract

This study presents the fabrication of novel antibacterial inorganic/organic composites containing Ag nanoparticles or carbon nanotubes and their applications for environmental materials. First, Biocidal poly(oxyethylene)s having N-halamine side groups were prepared using polymer analogous reactions of poly[oxy(chloromethyl)ethylene] with 5,5-dimethylhydantoin followed by chlorination. The biocidal poly(oxyethylene) films could inactivate the gram-negative bacteria, Escherichia coli effectively and they maintained their biocidal property after long term (3 months) storage. Since biocidal poly(oxyethylene) films have antibacterial efficacy and stability on hard surfaces, they could be useful for a variety of household and medical antibacterial applications. Second, We prepared polymeric N-halamine/silver nanoparticle composites to develop new effective biocidal systems. They were synthesized by mixing poly[oxy[(3-chloro-4,4-dimethyl-imidazolelidine-2,5-dionyl)methyl]ethylene](CI-P) with silver perchlorate followed by UV reduction. These composites exhibit potent antibacterial activity against the gram-negative bacteria, Escherichia coli. And we fabricated an innovative CNT-containing RO membrane with antifouling ability. Specifically, the antifouling properties were achieved by applying functionalized multiwalled carbon nanotubes (MWNTs) to the RO membrane and poly vinyl alcohol (PVA) was introduced to impede the loss of the CNTs. The CNTs were first modified by sulfuric acid to increase their sidewall functionalities and to achieve dispersion in aqueous solution. Characterization of the CNT-containing membrane demonstrated novel properties such as high performance in water separation processes. With the proper amount of functionalized CNTs, it was possible to increase both the flux and salt rejection of membranes. The presence of the antifouling MWNTs was confirmed by experimentation with P. aeruginosa cells, which demonstrated an enhanced bacterial cytotoxicity for the CNT-containing membranes. The permeate flux reductions on the PA/CNT/PVA membrane regardless of the concentration of the CNTs were about 30% less than that of both the PA membrane and commercialized RO membrane.