Cyclonic plasma activation on microporous poly(vinylidene fluoride) membranes for improving surface hydrophilicity

• PVDF membranes were modified using the cyclonic atmospheric-pressure plasma (CAPP).
• PVDF membrane surfaces became highly hydrophilic when exposed to CAPP for only 30 s.
• XPS analysis revealed a considerably high O content on the modified membrane surfaces.
• The CAPP-modified microporous PVDF membrane yielded a higher MF flux of pure water.
• CAPP was proven as a promising surface modification method for hydrophobic membranes.

To improve microfiltration (MF) flux, microporous poly(vinylidenefluoride) (PVDF) membranes were modified by cyclonic atmospheric-pressure plasma (CAPP). The surface hydrophilicity change of a PVDF membrane was monitored based on static contact angle measurements. The PVDF membrane surface became highly hydrophilic when exposed to CAPP for only 30 s. A significant increase in the surface energy of PVDF membranes attributable to the CASING (crosslinking via activated species of inert gases) effect was observed. Optical emission spectroscopy (OES) was used to determine various chemical species of CAPP processing. X-ray photoelectron spectroscopy (XPS) and confocal laser scanning microscopy (CLSM) were employed to characterize the chemical and morphological changes on the treated PVDF membrane surface. The XPS analysis showed considerably higher surface concentrations of oxygen functional groups on the CAPP-functionalized PVDF membrane surface compared to the untreated one. The membrane surface hydrophilicity was increased by plasma treatment, leading to an increase in filtration flux. The present results show that CAPP is an efficient tool that can be used to enhance the surface hydrophilicity of PVDF membranes.

The static contact angle analysis revealed that cyclonic plasma enhances the hydrophilicity of PVDF membranes. The cyclonic plasma-treated PVDF membrane yielded superior dead-end microfiltration flux than the untreated one. Cyclonic plasma holds a great potential to be used as the operative surface treatment technique for microporous PVDF membranes.Figure optionsDownload as PowerPoint slide