Hyperbranched-polymer functionalized multi-walled carbon nanotubes for poly (vinylidene fluoride) membranes: From dispersion to blended fouling-control membrane

To endow hydrophobic poly (vinylidene fluoride) (PVDF) membranes with reliable hydrophilicity and protein resistance, hyperbranched poly (amine-ester) functionalized multi-walled carbon nanotubes (MWNTHPAE) were prepared to develop MWNTHPAE/PVDF nanocomposite membrane. Various techniques such as transmission electron microscope, scanning electron microscopy, x-ray photoelectron spectroscopy and contact angle goniometry, as well as static protein adsorption and permeability experiments were applied to characterize the effect of MWNTHPAE on the morphology, permeability and anti-fouling performance of the nanocomposite membranes. The results showed that MWNTHPAE were randomly dispersed at the individual nanotube levels in the membrane without obvious agglomerations. The hydrophilicity of nanocomposite membrane was enhanced due to the surface coverage of hydrophilic hyperbranched poly (amine-ester) (HPAE) groups. Consequently, protein adsorption was significantly inhibited due to the hydrogen bonding interactions between hydrophilic groups and water molecules. This was also indicated by the higher flux recovery ratio of nanocomposite membranes in the protein filtration experiment. In addition, high water transport was obtained by the dual effect of hydrophilic MWNTHPAE and the pore structure of membrane.