Methodology for Robust Superhydrophobic Fabrics and Sponges from In Situ Growth of Transition Metal/Metal Oxide Nanocrystals with Thiol Modification and Their Applications in Oil/Water Separation

Abstract

Solid surfaces possessing both superhydrophobic and superoleophilic properties have attracted significant interest in fundamental investigations and potential applications in the fields of self-cleaning surfaces, oil/water separation, and microfluidic channels. In this paper, a general methodology for robust superhydrophobic fabrics and sponges was proposed via the in situ growth of both transition-metal oxides and metallic nanocrystals, including the simple neutralization reaction and oxidation-reduction reaction. The porous surfaces coated with Group VIII and IB nanocrystals (such as Fe, Co, Ni, Cu, and Ag) can not only present multiscale surface roughness, but also readily coordinate with thiols, leading to special wettability. In our previous work, it has been confirmed that the interaction between the nanocrystals and thiols plays a significant role in the introduction of hydrophobic ingredients. In this work, it has been demonstrated that the efficient control of the nucleation and growth of Group VIII and IB nanocrystals on the porous surfaces becomes the key factor in the formation of multiscale surface roughness, resulting in the achievement of controllable special wettability. In addition, these as-prepared superhydrophobic and superoleophilic fabrics and sponges were successfully used for application in oil/water separation.

Facile Fabrication of Superhydrophobic/Superoleophilic Cotton for Highly Efficient Oil/Water Separation

“…These materials have received increasing attention as an oil-absorbing material in oil/water separation for their microscale roughness in the integral fabric and their native porosity (Bi et al 2013;Wang et al 2013). Liu et al (2014) prepared superhydrophobic and superoleophilic SiO2-modified cotton for oil/water separation via a sol-gel process, which was initially pretreated by NaOH aqueous solution.…”

Recent Advances in the Fabrication of Superhydrophobic Surfaces

“…For example, a superhydrophobic surface was constructed on copper alloy sheets through immersing the substrates into the mixed solution of fluoroalkylsilane (FAS-17) molecules, ammonium persulfate ((NH 4 ) 2 S 2 O 8 ), and sodium hydroxide (NaOH) by Zhang et al 110 The obtained surface not only exhibited superhydrophobicity but also drag-reducing ability. Furthermore, some solution immersion processes may lead to the in situ growth of metal nanocrystals, which can strongly interact with low-surface-energy materials such as alkyl thiol etc., 26,27,75,120122 a new example is reported by Guo et al that reported stable superhydrophobic spongers and fabrics via immersing the substrates into a metal or transition-metal solution ( Figure 9). 26 Owing to the in situ growth of metal or transition metal oxide nanocrystals on the surface, the substrates can bond with thiols strongly.…”

“…Furthermore, some solution immersion processes may lead to the in situ growth of metal nanocrystals, which can strongly interact with low-surface-energy materials such as alkyl thiol etc., 26,27,75,120122 a new example is reported by Guo et al that reported stable superhydrophobic spongers and fabrics via immersing the substrates into a metal or transition-metal solution ( Figure 9). 26 Owing to the in situ growth of metal or transition metal oxide nanocrystals on the surface, the substrates can bond with thiols strongly. After solution immersion, the substrates may be modified by other substances to achieve functional superhydrophobicity.…”

“…to create appropriate roughness for coating. 9,16,2325,28 In addition, during the preparation process, it is worth mentioning that, when the prepared materials are coated on the substrate, the corresponding chemical reaction or ordered action may occur such as polymerization, 36 grafting, 74 self-assembly, 16 in situ growth, 26,27,75 and so on. Utilizing these actions, we can obtain expectable superhydrophobic coatings for a wide number of applications.…”

“…On the one hand, the effective methods to create appropriate roughness include electrodeposition, 915 chemical deposition, 1620 etching, 2125 in situ growth, 26,27 plasma process, 28 boiling water treatment, 29 and so on. On the other hand, the modification methods to decrease the surface energy include solution immersion, 3034 heat treatment, 13 electrodeposition, 1012,15 chemical vapor deposition, 14,20,22,28,35 polymerization on the substrate, 36 etc.…”