Side-chain grafted functional groups poly(vinylidene fluoride-hexafluoropropylene) anti-fouling fluorinated polymer membrane with tuneable hydrophobicity for distillation

We prepared side-chain grafted functional groups poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) fluorinated membranes to fine control hydrophobic and anti-fouling nature of membrane for desalination of high saline water by vacuum membrane distillation (VMD) process. Different functional groups viz. tri-methoxy silane, 4-methyl styrene, and 2, 3, 4, 5, 6-penta fluoro styrene were explored for side-chain grafting with PVDF-HFP matrix to improve the hydrophobic nature. Successful grafting of functional groups was confirmed by spectral analysis, while surface morphology of different membranes was assessed by scanning electron and atomic force microscopy. Membrane performance was assessed by permeate flux, fouling resistant nature, water contact angle and long-term performance. Among different prepared membranes, 2, 3, 4, 5, 6-penta fluoro styrene grafted PVDF-HFP membrane (M-PFS) was assessed suitable for VMD with permeate water flux (36% increase compared to the pristine membrane), salt rejection (99.99%), rechargeable (anti-fouling) nature by simple water washing, and longevity. The reported M-PFS membrane with novel architecture is a promising contender for desalination of high saline water by the VMD process.

Automated summary

In this study, side-chain grafted PVDF-HFP fluorinated membranes were prepared to enhance the hydrophobic and anti-fouling properties for desalination of high saline water using the VMD process. Different functional groups were explored for grafting with the PVDF-HFP matrix, and the 2,3,4,5,6-penta fluoro styrene grafted PVDF-HFP membrane showed promising performance with improved water flux, salt rejection, and fouling resistance.