Rapidly self-assembled polydopamine coating membranes with polyhexamethylene guanidine: Formation, characterization and antifouling evaluation

- A rapidly deposited PDA layer with PHMG was developed for hydrophilic modification.
- The PHMG had a significant impact on the dispersion and deposition of PDA coating.
- The diameter of PDA-PHMG capsules can be finely controlled at the nanometer scale.
- The modified membrane presented excellent permeation and antifouling performances.

A novel rapidly deposited polydopamine (PDA) layer with polyhexamethylene guanidine (PHMG) was developed for the modification of hydrophilic and antifouling poly(vinylidene fluoride) (PVDF) membranes on the basis of mussel-inspired surface chemistry in our latest work. The effect of PHMG on dopamine polymerization was investigated and experimental results demonstrated that the existence of water-soluble PHMG had a significant impact on the dispersion and deposition efficiency of PDA polymerized process due to strong interactions between PDA and PHMG. The morphology, structure, surface composition, and hydrophilicity of membranes were modified by the PDA-PHMG coating, as confirmed by scanning electron microscopy (SEM), confocal laser scanning microscope (CLSM), Fourier transform infrared spectroscopy (FTIR) and contact angle measurements. Acceleration of PDA polymerization was found to enhance the surface hydrophilicity and improve the water permeability of modified membranes. The PDA-PHMG coating membranes demonstrated excellent antifouling performances, including higher specific flux and flux recovery rate (FRR), lower adsorption of contaminants, and more resistant against irreversible fouling. The novel surface modification strategy was shown to be applicable to flat-sheet PVDF membranes and was relatively easy to operate under mild reaction conditions.

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