Mechanistic Applications of Nonlinear Effects in First-Row Transition-Metal Catalytic Systems

Knowledge of asymmetric catalytic reaction mechanism is very important for rational design and synthesis of new chiral catalysts or catalytic systems with high catalytic activity and stereoselectivity.The studies of nonlinear effect have attracted wide attentions as a simple and practical mechanistic tool to probe complex asymmetric catalytic reactions.

In situ reduction and functionalization of graphene oxide to improve the tribological behavior of a phenol formaldehyde composite coating

The development of a phenol formaldehyde/graphene(PF-graphene)composite coating with high performance is desirable but remains a challenge,because of the ultrahigh surface area and surface inertia of the graphene.Herein,we synthesized PF-graphene composites by the in situ polymerization of phenol and formaldehyde with the addition of graphene oxide,resulting in improved compatibility between the graphene and phenolic resin(PF)matrix and endowing the phenolic resin with good thermal stability and excellent tribological properties.Fourier-transform infrared(FTIR)spectra and X-ray diffraction(XRD)patterns demonstrated that the graphene oxide was reduced during the in-situ polymerization.The PF-graphene composites were sprayed onto steel blocks to form composite coatings.The effects of an applied load and of the sliding speed on the tribological properties of the PF-graphene composite coating were evaluated using a block-on-ring wear tester;in addition,the worn surface and the transfer film formed on the surface of the counterpart ring were studied by scanning electron microscopy(SEM).The results show that the PF-graphene composite coating exhibited enhanced tribological properties under all tested conditions.

Fabrication of Bionic Superhydrophobic Manganese Oxide/Polystyrene Nanocomposite Coating

A superhydrophobic manganese oxide/polystyrene （MnO2/PS） nanocomposite coating was fabricated by a facile spraying process. The mixture solution of MnO2/PS was poured into a spray gun, and then sprayed onto the copper substrate using 0.2 MPa nitrogen gas to construct superhydrophobic coating. The wettability of the composite coating was measured by sessile drop method. When the weight ratio of MnO2 to PS is 0.5：1, the maximum of contact angle （CA） （140°） is obtained at drying temperature of 180 ℃. As the content of MnO2 increases, the maximum of CA （155°） is achieved at 100 ℃. Surface morphologies and chemical composition were analyzed to understand the effect of the content of MnO2 nanorods and the drying temperature on CA. The results show that the wettability of the coating can be controlled by the content of MnO2 nanorods and the drying temperature. Using the proposed method, the thickness of the coating can be controlled by the spraying times. If damaged, the coating can be repaired just by spraying the mixture solution again.

Sliding wear behaviors of Nomex fabric/phenolic composite under dry and water-bathed sliding conditions

A Nomex fabric/phenolic composite was prepared,and its tribological properties were evaluated under dry and water‐bathed sliding conditions by a pin‐on‐disk tribometer.The resulting size of the friction coefficient for the Nomex fabric/phenolic composite in the study occurred in the following order:dry sliding condition>distilled water‐bathed sliding condition>sea water‐bathed sliding condition.The fabric composite’s wear rate from high to low was as follows:distilled water‐bathed sliding condition>sea water‐bathed sliding condition>dry sliding condition.Under water‐bathed sliding conditions,penetration of water into the cracks accelerated the composite’s invalidation process,resulting in a higher wear rate.We also found that the extent of corrosion and transfer film formed on the counterpart pin significantly influenced the wear rate of the Nomex fabric composite.Discussion of the Nomex fabric composite’s wear mechanisms under the sliding conditions investigated is provided on the basis of the characterization results.

An unusual superhydrophilic/superoleophobic sponge for oil-water separation

Development of porous materials with anti-fouling and remote controllability is highly desired for oil-water separation application yet still challenging. Herein, to address this challenge, a sponge with unusual superhydrophilicity/superoleophobicity and magnetic property was fabricated through a dip-coating process. To exploit its superhydrophilic/superoleophobic property, the obtained sponge was used as a reusable water sorbent scaffold to collect water from bulk oils without absorbing any oil. Owing to its magnetic property, the sponge was manipulated remotely by a magnet without touching it directly during the whole water collection process, which could potentially lower the cost of the water collection process. Apart from acting as a water-absorbing material, the sponge can also be used as affiliation material to separate water from oil-water mixture and oil in water emulsion selectively, when fixed into a cone funnel. This research provides a key addition to the field of oil-water separation materials.