Engineering multistructure poly(vinylidene fluoride) membranes modified by polydopamine to achieve superhydrophilicity, excellent permeability, and antifouling properties

Abstract

AbstractPolydopamine (PDA) was coated on poly(vinylidene fluoride) (PVDF) membranes with different structures to select the most suitable structure for achieving outstanding hydrophilicity, permeability, stability, and antifouling properties. PVDF membranes were prepared with different solvents (N‐methyl‐2‐pyrrolidone [NMP], N,N‐dimethylacetamide [DMAc], N,N‐dimethylformamide [DMF], NMP/DMAc, NMP/DMF, DMAc/DMF, and NMP/DMAc/DMF), and the factors that influenced the phase inversion were discussed. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM) were employed to characterize various membranes. Results indicated that PDA was coated on PVDF membrane surface and formed a smoother PDA layer. Water contact angle measurement confirmed the increased hydrophilicity of PDA modified membranes, but water flux decreased due to the adhesion of PDA on pore walls. The decrease of static adsorption of bovine serum albumin (BSA), the increase of flux recovery ratio (FRR), and the decline of fouling resistance for PDA modified membranes demonstrated that their antifouling properties have been improved significantly. The membrane prepared with NMP/DMAc displayed the highest decay rate of contact angle (16.6 ± 1.27%), the higher water flux (1358.5 ± 33.87 L m−2 h−1), the highest decrease of BSA adsorption (129.3 ± 5.02 μg cm−2), the highest increase rate of BSA rejection (13.6 ± 0.42%), and the highest FRR (92.8 ± 1.42%). This indicated that NMP/DMAc membrane possessed the most suitable structure to improve membrane performances by PDA coating.