Zhanjian Liu

A novel carbon nanotubes reinforced superhydrophobic and superoleophilic polyurethane sponge for selective oil–water separation through a chemical fabrication

Oil spillage and industrial oily wastewater have caused severe environmental concerns. A super absorbent material capable of separating oil–water mixtures, especially with a high absorption capacity and mechanical strength, is urgently desired. Here, a common and feasible approach to fabricate carbon nanotubes (CNTs) reinforced polyurethane (PU) sponge is presented that shows superhydrophobic and superoleophilic properties. The method involves the oxidative self-polymerization of dopamine and the reaction of hydrophilic polydopamine (PDA) with hydrophobic octadecylamine (ODA). The superhydrophobic stability of the as-prepared sponge with temperatures and in corrosive solutions of different pH is investigated. The as-prepared sponge could quickly and selectively absorb various kinds of oils up to 34.9 times of its own weight, and the absorbed oils can be collected by a simple squeezing process. More interestingly, the mechanical strength of the as-prepared sponge is improved due to the structural reinforcement of CNTs anchored on the sponge skeleton. Furthermore, the recovered sponge could be reused to separate oil–water mixture 150 times while maintaining its high absorption capacity. This promising multifunctional sponge exhibits significant potential as an efficient absorbent in large-scale oil–water separation applications.

Corrosion-resistant engineering superhydrophobic and superoleophilic bulk materials with oil–water separation property

A corrosion-resistant superhydrophobic and superoleophilic modified poly(vinylidene fluoride)-based bulk material with oil–water separation ability is fabricated through a facile method of molding and sintering process. Fluorinated ethylene propylene was added as the one of the cross-linking agents. Nanometer silica (SiO2) and carbon nanotubes (CNTs) were added into the bulk material to construct the necessary reticulate papillae structures for superhydrophobic surface. NH4HCO3 was added as a pore-forming reagent in order to realize porous structure and oil–water separation. The bulk material can be designed to different appearances, such as cuboids, cylinder and sealing rings. The resulting bulk material shows excellent superhydrophobic and superoleophilic with a water contact angle of 164° and oil contact angle of almost 0°. As the SiO2 and CNTs filled the entire bulk material, any section of the bulk material shows excellent superhydrophobicity. The thermal resistance of the bulk material was improved due to the introduction of nanoparticles. The corrosion resistance of the superhydrophobic bulk material was investigated in an aqueous NaCl solution (3.5%). The results show that the prepared composite bulk material is effective in corrosion resistance, primarily due to the barrier effect of Cassie–Baxter model of superhydrophobic surface. It is believed that this bulk material would be an engineering material for large-scale application.

Mechanical and tribological characteristics of carbon nanotube-reinforced polyvinylidene fluoride (PVDF)/epoxy composites

In this study, epoxy (EP) composites filled with different contents of polyvinylidene fluoride (PVDF) and carbon nanotubes (CNTs) were fabricated by the solvent evaporation and curing method. FT-IR and XRD analysis were performed to explore the discolorment mechanism of the PVDF/EP composites before and after curing. The effects of the PVDF and CNT content on the mechanical and tribological properties of the composites were investigated. Results revealed that 1.0% CNT/30% PVDF/EP composites exhibited a 36.2% and 10.1% increase in flexural strength and hardness, as compared to those of the 30% PVDF/EP composites. The wear rates of 1.0% CNT/30% PVDF/EP composites and 30% PVDF/EP composites were 92.1% and 86.8% lower than that of pristine EP under 1.0 MPa and 0.76 m s−1, respectively. Meanwhile, the fractured and worn surfaces of specimens were both analyzed by the observations of SEM. In addition, wear tests under various applied loads were conducted for pristine EP, 30% PVDF/EP and 1.0% CNT/30% PVDF/EP composites. The results showed that the wear properties of the two composites were both superior to those of pristine EP due to the formation of a transfer film as revealed by SEM-EDS analysis, which could effectively protect the worn surface from direct abrasion during the wear testing.

A superrobust superhydrophobic PSU composite coating with self-cleaning properties, wear resistance and corrosion resistance

In this study, a superhydrophobic polysulfone (PSU) composite coating with a high water contact angle (WCA) of 159° and a low slide angle (SA) of only 3.5° has been fabricated through a simple thermal spraying method. The ductility and mechanical properties of the PSU composite coating were improved effectively through the combination of the cross-linking ability of PVDF and the special multilayer structure of MMT. The wear resistance of the prepared coating is approximately 14.3 times longer than that of commercial fluorocarbon coating. Simultaneously, the prepared superhydrophobic coating also possesses outstanding corrosion resistance; the corrosion current and corrosion potential decreased from 10−0.9 to 10−3.6 μA cm−2 and from −803 to −218 mV, respectively. Furthermore, the prepared coating demonstrated superb self-cleaning, anti-fouling and durability properties. It is believed that this robust superhydrophobic PSU/PVDF/MMT–PDMS composite coating may provide the possibility to realize large-scale fabrication and applications in industry.