Multi-layer MoS2 : An Effective Barrier Enhancer and a Promising Nanofiller for Metal Protection

Two-dimensional nanomaterials are of great interest because of their unique properties and the great application potential in various fields. In this study, the performance of few-layer MoS2 nanosheets (MDNSs) as new nanofillers to enhance the barrier properties of poly(vinyl butyral) (PVB) is investigated. Gas permeability tests show that well-dispersed MDNSs can prevent at least 98% of oxygen molecules and 31% of water vapour from penetrating through the matrix of MDNS/PVB composites. Electrochemical analyses reveal that the corrosion rate of brass coated with the resulting composite coating is as low as 1.35×10− 8 mm/year, which is six orders of magnitude smaller than that of brass protected by a pristine PVB coating. These results indicate that MDNSs are highly effective barrier enhancers and suitable candidate materials for metal protection.

Comprehensive Analysis on Anomalous Phenomenon of Ethanol-Soluble PVB Membrane for Ethanol Recovery via Pervaporation

Poly(vinyl butyral) is selected as a promising ethanol-permselective membrane based the solubility parameter theory, however it exhibits anomalous water perm-selectivity in practical pervaporation process. Comprehensive analysis based on experimental and theoretical methods were carried out to explore the inherent mechanism of the anomalous performance. Firstly, sum frequency generation vibrational spectra and contact angle were developed to quantify the surface reconstruction of membrane in air and ethanol, which indicated that hydrophilic hydroxyl tended to expose on membrane surface with ethanol thus improved the membrane affinity to water. Meanwhile, swelling behaviors proved more water would accumulate in the ethanol swollen membrane. Furthermore, theoretical analysis in terms of sorption and diffusion process, based on the UNIFAC-FV model and Fujita free volume theory, confirmed the mechanism of anomalous phenomenon of poly(vinyl butyral) membrane. The comprehensive investigation was expected to provide insights into the basic separation mechanism of pervaporation process.