The optimal engineering of the surface properties was performed for poly(vinylidene fluoride) (PVDF)
membrane with hydrophobic surface-modifying macromolecules (SMMs). For this aim, new hydrophobic SMM additives were synthesized using polyurethane chemistry and characterized for water
contact angle, fluorine content and average molecular weight. Both modified PVDF/SMM and neat
PVDF membranes were prepared through phase inversion method in a single casting step and characterized by means of scanning electron microscope, energy-dispersive X-ray spectroscopy and contact angle goniometry. The optimum preparation conditions were determined using response surface
methodology. The effects of the main casting variables, such as PVDF concentration, SMM concentration and solvent evaporation time, on the surface properties of the synthesized membrane were
identified and used to prepare optimal PVDF/SMM membrane. The prepared membranes were tested
for permeation flux and salt rejection efficiency by membrane distillation process. The results indicate
that the optimally modified membrane yields high permeate flux of around 17.5 kg/m2
h and total salt
rejection efficiency of 99.9 % compared with pristine membranes. In particular, the hydrophobicity of
the modified membrane significantly increases up to 108° at water contact angle, through presented
surface modification procedure
