Properties of membranes containing semi-dispersed carbon nanotubes

Carbon nanotubes exhibit superior mechanical and electrical properties that make them attractive for developing new composite materials. In this research, we examined the properties of ultrafiltration membranes made from carbon nanotube/polymer composites. Multiwalled carbon nanotubes (MWCNT, 4% w/w) were incorporated into polysulfone ultrafiltration membranes, prepared according to the wet phase inversion method. The dispersion of the nanotubes and the morphology of the membranes were observed by scanning electron microscopy. The membranes were characterized for surface roughness, contact angle, permeability, and mechanical properties. A partial deaggregation of the nanotubes leads to individual nanotubes within the polymer as well as bundles nested in the pores. After addition of MWCNTs, the assymetric structure of the membrane, the permeability, and the hydrophobicity were not disturbed, but the roughness increased. Contrary to expectations, the tensile strength of the composite membrane was not improved while the elongation to failure decreased because of a lack of dispersion of the nanotubes. Growth of bacteria on the membranes was tested using two different methods, neither of which indicated an antibacterial effect due to the presence of nanotubes.