In order to improve the water permeability of poly(vinylidene fluoride) (PVDF) ultrafiltration (UF) membranes with low molecular weight cut-off (MWCO)

polydopamine (PDA) was employed in the membrane preparation process. Owing to its merits of material-independent adhesion

PDA was coated on inorganic particles or added in coagulation bath to tailor the final membrane structure and property. The introduction of PDA broke through the permeability/selectivity trade-off of the PVDF membrane. By adding the PDA coated titanium dioxide (PDA/TiO

2

) nanoparticles

water flux increased by 287% while MWCO kept similar with the pristine PVDF membrane. Thermodynamics and Kinetics of the PVDF/additives/non-solvent were analyzed and shown that nanoparticles reduced the thermodynamic stability and increased the phase separation speed

and the speed can be adjusted using different nanoparticles. Additionally

X-ray diffraction (XRD) test indicated that PVDF crystalline form changed from α phase to β phase after adding different nanoparticles. Permeability/selectivity trade-off was broken through by DA addition in coagulation bath. Compared with the original PVDF mem

brane

when the DA concentration of the coagulation bath was 2.0 g·L

-1

water flux increased by 312%

and MWCO of the PVDF membrane ranged in 10

000 to 20

000 Da as well as contact angle decreased from 81.4° to 45°.