Formation of hollow fiber membranes doped with multiwalled carbon nanotube dispersions

The structure and properties of dispersions of pristine and covalently modified multiwalled carbon nanotubes (MWCNTs) in N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF) and water have been studied. It has been shown that the dispersions in NMP have the highest stability and smallest particle size. The study of MWCNT dispersions in DMAc with various dispersing polymers, such as polyvinylpyrrolidone (PVP), polyethylene glycol, block copolymers of polyethylene glycol and polypropylene glycol of various molecular weights, ethylenediamine tetrakis(ethoxylate-block-propoxylate) tetrol, and ethylenediamine tetrakis(propoxylate-block-ethoxylate) tetrol has revealed that PVP has the best dispersing capacity. It has been found that the particle size and the yield of MWCNTs dispersed in DMAc depend on the nature and molecular weight of the dispersing polymer, as well as on the solvent quality. Polysulfone hollow fiber ultrafiltration membranes with PVP-modified MWCNT additives (PVP is one of the components of the spinning solutions) have been prepared by the phase inversion method. It has been found that the addition of 0.00084-0.0048% MWCNT in a spinning solution makes it possible to vary the transport properties of the hollow fiber membranes in a wide range.