Hydrophilic PVDF membrane with versatile surface functions fabricated via cellulose molecular coating

Hydrophilic PVDF membrane was fabricated in single step via cellulose molecular coating prepared by homogeneous solution of cellulose oligomer synthesized by enzyme catalysis (EC)/Trifluoroacetic acid (TFA). Both smooth and rough coatings can be prepared by regulating the aggregative structure of cellulose molecular coatings. The chemical structures of the cellulose and its coating were confirmed by 1H Nuclear Magnetic Resonance Spectroscopy (1H NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The aggregation structure of the cellulose coating was characterized by wide-angle X-ray diffraction (WAXD). X-ray Photoelectron Spectroscopy (XPS) studies unveiled the strong binding of cellulose molecular to PVDF membranes at the interface. Scanning Electron Microscopy (SEM) morphologies show that the cellulose molecules were uniformly coated on the surface and cross section of the membranes. Water contact angle measurement suggested that cellulose molecular coating possessed high hydrophilicity and wetting rate, giving the PVDF membranes high water flux and excellent anti-fouling performances. The coated membranes also show excellent adsorption and desorption performances for crystal violet (CV). The superior performances of incompletely crystallized cellulose coating over amorphous cellulose coating were attributed to the increased specific surface area resulting from the surface roughness. The construction of cellulose molecular coating with controlled aggregation structure provides a novel efficient technology in the field of purification of wastewater, opening up a new approach to the microstructural manipulation of the hydrophilic coating.

Automated summary

Hydrophilic PVDF membranes were successfully fabricated in a single step by coating with cellulose oligomers synthesized via enzyme catalysis, resulting in improved water flux, anti-fouling properties, and adsorption/desorption capabilities for crystal violet. The partially crystallized cellulose coating exhibited superior hydrophilicity compared to the amorphous coating due to increased specific surface area from surface roughness. This novel technology of controlled aggregation structure of cellulose molecular coating opens up new possibilities in wastewater purification and microstructural manipulation of hydrophilic coatings.