Shuzhen Li

Rare bi-wetting TiO2-F/SiO2/F-PEG fabric coating for self-cleaning and oil/water separation

A TiO2-F/SiO2/F-PEG coating (TiO2-F:TiO2 modified with fluorocarbon surfactant; F-PEG: resin modified with fluorocarbon surfactant and polyethylene glycol) was fabricated via a three-step mild addition polymerization, followed by uniform dispersion of inorganic nanoparticles. The organic fluorine and hydrophilic polyether groups were introduced by surface grafting, in which the fluorinated polymer provided low surface energy. Surface characteristics of TiO2-F/SiO2/F-PEG coated polyester fabric were analyzed by contact-angle measurement (CA), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS). Oil/water separation efficiency was proven via thermogravimetric analysis (TGA). SiO2 particles, as fine as about 200 nm, were dispersed over the fabric with the as-fabricated coating. The hierarchical roughness structure featured two length scales; the microstructure of the polyester fabric and the nanostructure of the inorganic particles. This unique structure brought about a rare bi-wetting property, through which the coating was both super-hydrophilic (θwater ≈ 0° in air) and super-oleophobic (θoil ≈ 146° in air, and θoil,max ≈ 164° under water). Oil/water separation efficiency reached 99% solely via gravity-driven separation at room temperature. Furthermore, the coated fabric still maintained 98% separation efficiency after 16 cycles. Moreover, it offered good high temperature resistance, acid and alkali resistance and mechanical tensile strength. The rare bi-wetting ability of the TiO2-F/SiO2/F-PEG coating can be expected to contribute to other desirable properties of functional surface materials, such as self-cleaning and oil–water separation.

Tribological Studies on Two Novel Borate Esters with Nitrogen-Containing Heterocyclic and Alkanolamide as Multifunctional Additives in Rapeseed Oil

Borate esters have good load carrying capacity and lubricating properties. However, borate esters are susceptible to hydrolyzation, which limits their applications. To improve the hydrolysis resistance of borate esters, nitrogen-containing heterocyclic and alkanolamide were introduced into their structures. Two novel multifunctional borate esters were synthesized, and their tribological properties were evaluated in rapeseed oil. The two novel borate esters showed superior tribological properties, as well as excellent anti-rust, anti-corrosion, and anti-oxidant properties. During friction, the mixed film containing B2O3 and nitrogen-containing organic compounds were formed, iron oxide generated on the worn surface, which were important to anti-wear. GRAPHICAL ABSTRACT