Recent developments in air-trapped superhydrophobic and liquid-infused slippery surfaces for anti-icing application

Latthe, Sanjay S.,Sutar, Rajaram S.,Bhosale, Appasaheb K.,Nagappan, Saravanan,Ha, Chang-Sik,Sadasivuni, Kishor Kumar,Liu, Shanhu,Xing, Ruimin Elsevier 2019 Progress in organic coatings Vol.137 No.-

<P><B>Abstract</B></P> <P>Anti-icing coating is one of the recent hot topics in industrial applications as well as from the academic viewpoint. Icing is one of the major problem on various substrates such as glass windows in buildings as well as vehicles, solar panels, wind turbine blades, airplanes, transmission lines, power towers, traffic signals, off-shore oil platforms, telecommunication antennas, and many others. Ice accumulation can significantly reduce the performance of the substrates and results in poor visibility. Recently, considerable attention is being paid on the naturally inspired superhydrophobic/icephobic surfaces by mimicking its surface property for the development of artificial self-cleaning superhydrophobic and ice-phobic surfaces. A good example is the lotus leaf surface where hierarchical micro and nano-scale rough structure covered by low surface energy coating layer on the leaf can repel water droplets and prevent ice accumulation. On superhydrophobic surfaces, impacting and condensed water droplets rolled off before freezing at subzero temperature. On the other hand, in slippery liquid-infused porous surface (SLIPS), the air pockets are replaced by immiscible lubricant film which can easily remove the accumulated ice without any damage to the surface. In this review article, we describe the recent progress in passive anti-icing coating materials and methodologies. Metal substrates, polymers, and nanoparticles/polymer composites are playing the major role in the development of anti-icing surface. So, the main goal of this review articles deals with the development of various synthetic routes of superhydrophobic anti-icing coating materials from metal substrates, polymers, and nanoparticles/polymer composites. In addition, the role of SLIPS in anti-icing coating and their use are also discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This review article explores the recent developments done in fabricating the anti-icing surfaces. </LI> <LI> Various new ideas, materials, fabrication techniques and prospects are thoroughly discussed. </LI> <LI> The merit/demerits of various anti-icing surfaces were identified and discussed. </LI> <LI> This review article is beneficial for graduate, post-graduate students and experts in this research field. </LI> </UL> </P>

High energy electron beam irradiated TiO2 photoanodes for improved water splitting

Latthe, S.,An, S.,Jin, S.,Yoon, S. Royal Society of Chemistry 2013 Journal of Materials Chemistry A Vol.1 No.43

A highly transparent self-cleaning superhydrophobic surface by organosilane-coated alumina particles deposited via electrospraying

Yoon, H.,Kim, H.,Latthe, S.,Kim, M. w.,Al-Deyab, S.,Yoon, S. Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.21

Dynamic Electrowetting-on-Dielectric (DEWOD) on Unstretched and Stretched Teflon

Lee, Min Wook,Latthe, Sanjay S.,Yarin, Alexander L.,Yoon, Sam S. American Chemical Society 2013 Langmuir Vol.29 No.25

<P>Dynamic electrowetting-on-dielectric (DEWOD) of the unstretched and stretched Teflon is reported in the experiments with water drop impact and rebound. We explore experimentally and theoretically the situation with the capacitance different from the standard static electrowetting. Deionized water drops impact onto either an unstretched hydrophobic Teflon surface or Teflon stretched up to 250% strain normally to the impact direction. The surface roughness of the unstretched Teflon increased after stretching from 209.9 to 245.6 nm resulting in the increase in the equilibrium water contact angle from 96 ± 4° to 147 ± 5°, respectively. The electric arrangement used in the drop impact experiments on DEWOD results in a dramatically reduced capacitance and requires a much higher voltage to observe EW in comparison with the standard static case of a drop deposited on a dielectric layer and attached to an electrode. In the dynamic situation we found that as the EW sets in it can greatly reduce the superhydrophobicity of the unstretched and stretched Teflon. At 0 kV, the water drop rebound height (<I>h</I><SUB>max</SUB>) is higher for the stretched Teflon (<I>h</I><SUB>max</SUB> ≈ 5.13 mm) and lower for the unstretched Teflon (<I>h</I><SUB>max</SUB> ≈ 4.16 mm). The EW response of unstretched Teflon is weaker than that of the stretched one. At the voltage of 3 kV, the water drop sticks to the stretched Teflon without rebound, whereas water drops still partially rebound (<I>h</I><SUB>max</SUB> ≈ 2.8 mm) after a comparable impact onto the unstretched Teflon. We found a sharp dynamic EW response for the stretched Teflon. The contact angle of deionized water ranged from 147 ± 5° (superhydrophobic) to 67 ± 5° (partially hydrophilic) by applying external voltage of 0 and 3 kV, respectively. Dynamic electrowetting introduced in this work for the first time can be used to control spray cooling, painting, and coating and for drop transport in microfluidics.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2013/langd5.2013.29.issue-25/la401669w/production/images/medium/la-2013-01669w_0014.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la401669w'>ACS Electronic Supporting Info</A></P>

Electrospun Polystyrene Nanofiber Membrane with Superhydrophobicity and Superoleophilicity for Selective Separation of Water and Low Viscous Oil

Lee, Min Wook,An, Seongpil,Latthe, Sanjay S.,Lee, Changmin,Hong, Seungkwan,Yoon, Sam S. American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.21

<P>The ability to prepare solid surfaces with well-controlled superhydrophobic and superoleophilic properties is of paramount importance to water–oil separation technology. Herein, we successfully prepared superhydrophobic-superoleophilic membranes by single-step deposition of polystyrene (PS) nanofibers onto a stainless steel mesh via electrospinning. The contact angles of diesel and water on the prepared PS nanofiber membrane were 0° and 155° ± 3°, respectively. Applications of the PS nanofiber membrane toward separating liquids with low surface tension, such as oil, from water were investigated in detail. Gasoline, diesel, and mineral oil were tested as representative low-viscosity oils. The PS nanofiber membranes efficiently separated several liters of oil from water in a single step, of only a few minutes’ duration. The superhydrophobic PS nanofiber membrane selectively absorbs oil, and is highly efficient at oil–water separation, making it a very promising material for oil spill remediation.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-21/am404156k/production/images/medium/am-2013-04156k_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am404156k'>ACS Electronic Supporting Info</A></P>

Thermally Induced Superhydrophilicity in TiO₂ Films Prepared by Supersonic Aerosol Deposition

Park, Jung-Jae,Kim, Do-Yeon,Latthe, Sanjay S.,Lee, Jong-Gun,Swihart, Mark T.,Yoon, Sam S. American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.13

<P>Superhydrophilic and superhydrophobic surfaces enable self-cleaning phenomena, either forming a continuous water film or forming droplets that roll off the surface, respectively. TiO<SUB>2</SUB> films are well-known for their extreme hydrophilicity and photocatalytic characteristics. Here, we describe nanostructured TiO<SUB>2</SUB> thin films prepared by supersonic aerosol deposition, including a thorough study of the effects of the annealing temperature on the crystal structure, surface morphology, surface roughness, and wetting properties. Powder X-ray diffraction showed that supersonic deposition resulted in fragmentation and amorphization of the micrometer-size anatase (60%)–rutile (40%) precursor powder and that, upon annealing, a substantial fraction of the film (∼30%) crystallized in the highly hydrophilic but metastable brookite phase. The film morphology was also somewhat modified after annealing. Scanning electron microscopy and atomic force microscopy revealed rough granular films with high surface roughness. The as-deposited TiO<SUB>2</SUB> films were moderately hydrophilic with a water contact angle (θ) of ∼45°, whereas TiO<SUB>2</SUB> films annealed at 500 °C became superhydrophilic (θ ∼ 0°) without UV illumination. This thermally induced superhydrophilicity of the TiO<SUB>2</SUB> films can be explained on the basis of the combined effects of the change in the crystal structure, surface microstructure, and surface roughness. Supersonic aerosol deposition followed by annealing is uniquely able to produce these nanostructured films containing a mixture of all three TiO<SUB>2</SUB> phases (anatase, rutile, and brookite) and exhibiting superhydrophilicity without UV illumination.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-13/am401083y/production/images/medium/am-2013-01083y_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am401083y'>ACS Electronic Supporting Info</A></P>

Highly Efficient Wettability Control via Three-Dimensional (3D) Suspension of Titania Nanoparticles in Polystyrene Nanofibers

Lee, Min Wook,An, Seongpil,Joshi, Bhavana,Latthe, Sanjay S.,Yoon, Sam S. American Chemical Society 2013 ACS APPLIED MATERIALS & INTERFACES Vol.5 No.4

<P>Electrospinning is a simple and highly versatile method for the large-scale fabrication of polymeric nanofibers. Additives or fillers can also be used to functionalize the nanofibers for use in specific applications. Herein, we demonstrate a novel and efficient way to fabricate superhydrophobic to hydrophilic tunable mats with the combined use of electrospinning and electrospraying that may be suitable for mass production on the merits of rapid deposition. The tunable nanocomposite mats were comprised of hydrophobic polystyrene nanofibers and hydrophilic titania nanoparticles. When the electrical conductivity of the electrospinning solution was increased, the surface morphology of the mats changed noticeably from a bead-on-string structure to an almost bead-free structure. Polystyrene (PS)–titania nanocomposite mats initially yielded a static water contact angle as high as 140° ± 3°. Subsequently exposing these mats with relatively weak ultraviolet irradiation (λ = 365 nm, <I>I</I> = 0.6 mW/cm<SUP>2</SUP>) for 2 h, the unique 3D suspension of the photoactive titania nanoparticles maximized the hydrophilic performance of the mats, reducing the static water contact angle to as low as 26° ± 2°. The tunable mats were characterized by scanning electron microscopy (SEM), static water contact angle (WCA) measurements, and energy-dispersive X-ray spectroscopy (EDX). Our findings confirmed that the tunable mats fabricated by the simultaneous implementation of electrospraying and electrospinning had the most efficient ultraviolet (UV)-driven wettability control in terms of cost-effectiveness. Well-controlled tunable hydrophobic and hydrophilic mats find potential applications in functional textiles, environmental membranes, biological sensors, scaffolds, and transport media.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2013/aamick.2013.5.issue-4/am303008s/production/images/medium/am-2012-03008s_0009.gif'></P>

Graphene-ZnO 전기방사 나노섬유를 이용한 물분해 연구

이민욱(Min-Wook Lee),Sanjay Latthe,안성필(Seongpil An),윤석구(Sam S. Yoon) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.5

Gravity-Driven Hybrid Membrane for Oleophobic–Superhydrophilic Oil–Water Separation and Water Purification by Graphene

Yoon, Hyun,Na, Seung-Heon,Choi, Jae-Young,Latthe, Sanjay S.,Swihart, Mark T.,Al-Deyab, Salem S.,Yoon, Sam S. American Chemical Society 2014 Langmuir Vol.30 No.39

<P>We prepared a simple, low-cost membrane suitable for gravity-driven oil–water separation and water purification. Composite membranes with selective wettability were fabricated from a mixture of aqueous poly(diallyldimethylammonium chloride) solution, sodium perfluorooctanoate, and silica nanoparticles. Simply dip-coating a stainless steel mesh using this mixture produced the oil–water separator. The contact angles (CAs) of hexadecane and water on the prepared composite membranes were 95 ± 2° and 0°, respectively, showing the oleophobicity and superhydrophilicity of the membrane. In addition, a graphene plug was stacked below the membrane to remove water-soluble organics by adsorption. As a result, this multifunctional device not only separates hexadecane from water, but also purifies water by the permeation of the separated water through the graphene plug. Here, methylene blue (MB) was removed as a demonstration. Membranes were characterized by high-resolution scanning electron microscopy (HRSEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FT-IR) spectroscopy to elucidate the origin of their selective wettability.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2014/langd5.2014.30.issue-39/la5031526/production/images/medium/la-2014-031526_0015.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la5031526'>ACS Electronic Supporting Info</A></P>