Smart Nanocoating (Metal oxide andComposite) and its surfacefunctionalization for EnvironmentalRemediation

Palaniswamy Suresh Kumar and Pon Sathya Moorthy

ContentsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Classification of Surface Wetting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Coating Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Nanocoating for the Superhydrophobic Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Metal Oxide Coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Composite-Based Coating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Surface Functionalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

AbstractThis chapter is based on the recent literature on the superhydrophobic surfacecoated using various kinds of nanostructured materials (such as metal oxide andcomposite) and surface functionalizaton. Superhydrophobic surfaces repel watergenerally due to their surface texture or chemical properties, and surface pos-sesses a high apparent contact angle (>150�) and very low sliding angle (<5�).Superhydrophobic coatings have received great attention worldwide for its multi-functional application in automotive, marine, and building sector.

KeywordsNanostructure materials · Metal oxide · Composite · Nanocoating · Surfacewettability · Self-cleaning surface

P. S. Kumar (*)Environmental and Water Technology Centre of Innovation (EWTCOI), Ngee Ann Polytechnic,Singapore, Singaporee-mail: Sureshinphy@yahoo.com

P. S. MoorthyDepartment of Nanoscience and Technology, Tamil Nadu Agricultural University, Coimbatore,India

© Springer Nature Switzerland AG 2020C. M. Hussain, S. Thomas (eds.), Handbook of Polymer and Ceramic Nanotechnology,https://doi.org/10.1007/978-3-030-10614-0_40-1

1

Introduction

Nanostructure materials have gained wide attention owing to their multifunctionalproperties such as surface, structural, optical, and mechanical. Over the past fewyears, nanomaterial-based coatings are response to extreme environment conditions(such as temperature, humidity, pollutant) and are applied for multifunctional appli-cation such as self-cleaning superhydrophobic, anti-microbial and photocatalytic,(Jeevaham et al. 2018; Mahltig et al. 2016; Wu et al. 2018). According to a report byGrand View Research Inc., the global smart coating market was estimated aroundUSD 885.5 million in 2015 and expected to reach around USD 11.68 billion by 2024which is projected to grow at a compound annual growth rate (CAGR) of 31.5% overthe forecast period, owing to multifunctional application. However, the Asia Pacificrecorded a market value of USD 171.8 million in 2015 for smart coating with theCAGR of 38.6% from 2016 to 2024 due to the increasing product demand fromemerging economies of China, India, Vietnam, and Indonesia (https://www.grandviewresearch.com/press-release/global-smart-coating-market).

Inspired by Mother Nature, biomimetic materials with smart structures andfunctions are inspired to be fabricated. Numerous plant leaf and biological surfacesexhibit excellent water-repellent behavior. Compared to other natural plant leaves,the lotus (Nelumbo nucifera) is a semiaquatic plant which has been popularly knownas a symbol of purity in Asian culture for over 2000 years due to its capability toremain clean (Nishimoto and Bhushan 2013; Zhang et al. 2016). Figure 1 shows anoverview of biomimetic self-cleaning surfaces inspired by different biologicalobjects. Superhydrophobic surfaces (such as metals, glasses, textiles, aerogels, andpaper) have gained tremendous attention due to their anti-wetting, anticorrosion, oil-water separation, self-cleaning, anti-icing, and antibacterial properties.

Classification of Surface Wetting

Surface wetting behaviors of a surface are mainly classified by three models, i.e.,Young’s equation, Wenzel model, and Cassie model. Contact angle (CA) measure-ment is adopted for the characterization of the wettability of surfaces, and CA is theunit for the surface wettability. A high CA describes surfaces on which a waterdroplet forms a spherical droplet shape and the real contact between the adheringwater droplet and the surface is very small. Ideally, the contact surface is referred toas being smooth, and the apparent WCA is explained in the air by Young’s equation:

cos θ0 ¼ γSA � γSWγWA

where ϴ0 stands for the value of water contact on a solid surface and γSA, γSW, andγWA are the surface tension of solid in the air, the surface tension of liquid in the air,and the interface energy between the solid and liquid, respectively. However, the twomodels (the Wenzel and Cassie model) are commonly involved in the surface

2 P. S. Kumar and P. S. Moorthy

roughness with the apparent contact angles (CA). In Wenzel model, the water dropletare in contact with the surface are completely fills in the valleys of the rough surface.The WCA ϴw on the rough surface is presented in the Wenzel state (Wang et al.2012):

Cos θW ¼ r Cos θ0

where r (r> 1) means the ratio of the real contact line to the projected contact line ofthe portion of solid in the air. It is shown in the equation that the combined effect ofsurface morphology (r) and the surface chemical composition (θ0) is observed to bethe decisive factor influencing the apparent CA. Nevertheless, the absolute value ofrcos y0 might be larger than 1 in some surfaces with high roughness or porousstructures. So the Wenzel model is insufficient, and the Cassie model will be used tointroduce such wetting behavior. The apparent change in contact angle as a functionof surface roughness is shown in Fig. 2a.

Fig. 1 Overview of biomimetic self-cleaning surfaces inspired by biological objects (Zhang et al.2016)

Smart Nanocoating (Metal oxide and Composite) and its surface. . . 3

A composite state was formed, resulting from liquids only contacting the solidthrough the top of the asperities, whereas air pockets are trapped underneath theliquid. It also demonstrates that the air constructs a perfect non-wetting state. Theapparent CA θC in the Cassie model can be described as:

Cos θc ¼ rfCos θ0 þ f -1

where f is the solid-water fraction under the contact area. rf shows a lower value thanr in the Wenzel model and is defined as the roughness ratio of the wet part of the solidsurface. The solid-water fraction f (solid-air fraction), similar to r, is also suggestedas an influencing parameter to the apparent CA. Figure 2b shows the effects ofsurface morphology and surface energy (high and low) on wettability. So far, effortshave been made to mimic the superhydrophobicity from nature and develop anartificial superhydrophobic surface with different functional nanomaterials throughcoating process.

Coating Techniques

The coating is defined as the process of deposition on a surface with a thin layercoating of specific nanomaterials in the liquid phase (solution) or solid phase(powder or nanoparticles). Variety of coating techniques such as sol-gel, layer-by-layer dip coating, hydrothermal, spin coating, spray coating, and electrospinningwere adopted for the fabrication of superhydrophobic surfaces (Li et al. 2015;Balgude and Sabnis 2012). All these methods are adopted based on the specifictype of coating solution, materials, and surfaces, and it is a technical challenge toidentify a single method for coating applications for metal surface, glass surface,solar panel, automobiles, and building material.

180θ=125°

θ=115° θ=105°High energy surface Low energy surface

Hydrophobic surfaceHydrophobic surface

(a) (b)

(c) (d)

(e) (f)

Rou

gh s

urfa

ceF

lat s

urfa

ce

Su

rfac

e m

orp

ho

log

y

Surface material

Full wetting

Partial wetting

*Reentrant textured surface

θ=95°qe

qe

qwqw

qc qc

θ=90°

θ=85°

θ=75°θ=65°

θ rou

gh[°

]

θ=55°

135

90

45

01 2 3 4 5

Fig. 2 (a) Apparent contact angle as a function of surface roughness (Shang 2005) and (b) effectsof surface morphology and surface energy on wettability (Lee et al. 2019)

4 P. S. Kumar and P. S. Moorthy

Wet chemistry-based sol-gel is a common technique for the preparing of high-quality nanostructured coating that cannot be achieved by other methods. Nano-coating has been produced mainly in two ways by sol-gel method. One way is toprepare a hydrophobic surface with a co-precursor which acts as a hydrophobicreagent, and the other is to modify a surface by surface derivatization method. Thedipping and spray coating or combination of dip- and spray-coating methods isparticularly adopted for superhydrophobic-based coating on different surfaces.These solution-based coatings are cost-effective and can be performed at roomtemperature without any sophisticated equipment which required a high vacuumcondition and temperature. Schematic images of the various coating method areshown in Fig. 3. Dip coating is readily applied onto almost any substrate withuniform coating on large surface areas. Dip-coating processes are highly desirablefor practical industrial applications due to their relatively simple process. Thesuperhydrophobic coating is performed by the following four main steps: (1) sol-gel preparation, (2) nanocoating, (3) posttreatment/annealing of the coating, and (4)surface derivatization. This book chapter gives an overview of the different nano-structured metal oxide, composite-based self-cleaning superhydrophobic coatingwith and without surface functionalization and its corresponding surface wettabilitybehavior.

Nanocoating for the Superhydrophobic Application

Metal Oxide Coating

So far, metal oxides such as SiO2, ZnO, CuO, and CeO2 and its composite materialswere synthesized and deposited in the form of superhydrophobic nanostructured thinfilms with and without surface modification on different surfaces through a solution-based coating process. S. S. Latthe et al. have successfully developed a self-cleaningsuperhydrophobic SiO2 nanoparticle (NP) coated on substrates using a dip and spraydeposition layer. The coated substrate with silica (SiO2) nanoparticles (NPs)exhibited superhydrophobicity with water contact angle (WCA) nearly 160� andsliding angle less than 6� for surface coated on the body of motorcycle, buildingwall, mini boat, solar cell panel, window glass, cotton shirt, fabric shoes, paper,metal, wood, sponges, plastic, and marble (Latthe et al. 2019). S. A. Mahadik et al.have developed organically modified SiO2 superhydrophobic coatings which areprepared by a simple, inexpensive sol-gel dip-coating process with higher thermalstability, durability, and superoleophobic nature (Mahadik et al. 2013). A.B.. Guravet al. have developed self-cleaning superhydrophobic SiO2 coatings using a dip-coating technique. Figure 4 a,b shows the optical images of the superhydrophobicSiO2 coating prepared after three dips. By adopting a multilayer deposition process,a superhydrophobic silica coating with a water contact angle (WCA) of 153� � 2�

and roll-off angle of 8� � 1� was developed Gurav et al. (2015). C. Zhang et al. havedeveloped the transparent and durable superhydrophobic SiO2 coating on varioussubstrates via one-step spraying without subsequent modification or treatment. The

Smart Nanocoating (Metal oxide and Composite) and its surface. . . 5

coating has achieved superhydrophobic with the water contact angle (WCA) higherthan 160�, a SA less than 3�, and a CAH less than 8� (Zhang et al. 2019a). Y. Zhanget al. have fabricated a simple two-step immersion method with the repairablesuperhydrophobic SiO2 surface. The coating exhibits excellent robustness undermechanical abrasion or impact damage (1600 to 20,000 cm) (Zhang et al. 2019b).Q. Cheng et al. have prepared the micro-nanostructure superhydrophobic SiO2

coating through a facile spray-coating method with the contact angle (CA) of155.9� and the sliding angle (SA) less than 1� with good transparency properties(Cheng et al. 2019).

P.S. Kumar et al. have developed a simple and cost-effective successive ioniclayer adsorption and reaction (SILAR) dipping method which was adopted tofabricate hydrophobic ZnO nanostructured surfaces on transparent indium tinoxide (ITO), glass, and polyethylene terephthalate (PET) substrates. ZnO nanostruc-tured films had contact angles of �140� and 160� � 2 on glass and PET substrates

(a) Plasma etching

(b) Electrospinning

(c) Polymerization

(d) Spin coating

(e) Spary coating

Polymerization

Polymers

Plasmaetching

Voltage source

Polymer Polymer

Polymers

Monomers

Polymer

Any substrate

Any substrate

Any substrate Any substrate

Any substrate Any substrateAny substrate

Any substrate

Any substratePolymers

(f) Dip coating

Any substrate

Any substrate

Any substrate Any substrate

Any substrate Any substrate

UV cure

Surfacefluorination

Fig. 3 Schematic image of the various methods for coating (Wu et al. 2016)

6 P. S. Kumar and P. S. Moorthy

and exhibit the hydrophobic behavior without any surface modification or treatment(Kumar et al. 2011a). P. S. Kumar et al. have developed the surface wettability ofZnO nanorods which showed a superhydrophobic behavior with a specific watercontact angle (WCA) of�160� which was attained without any surface modificationor pretreatment. Similarly, hierarchical hydrophobic zinc oxide (ZnO) micro�/nanostructured thin films were grown onto as-prepared seed layer and annealedZnO seed layer films prepared by a simple two-step chemical process (Kumaret al. 2013, 2011c). A. Hooda et al. have developed a transparent superhydrophobicpolystyrene/ZnO nanocoating having an average roughness of 28 nm and highcontact angle (>150�) (Hooda et al. 2017). T. Movahedi et al. research group hasfabricated the micro/nano hierarchical ZnO superhydrophobic surfaces(WCA = 165.1�) on iron plates via chemical bath deposition (CBD) method andmodified with stearic acid (STA) (Movahedi and Norouzbeigi 2019). Y. Gao et al.have developed the highly transmissive (avg. 93–95%) and UV-resistant super-hydrophobic coating based on SiO2�coated ZnO nanorod arrays on both glass andPET substrates (Gao et al. 2014). D. Ebert et al. have fabricated the transparentsuperhydrophobic surfaces onto different substrates such as glass, polycarbonate,and poly(methyl methacrylate) (PMMA) using surface-functionalized SiO2, ZnO,and indium tin oxide (ITO) nanoparticles (NPs) (Ebert and Bhushan 2012). H. Liet al. have fabricate a superhydrophobic Zn coating with ZnO nanosheets on steelsubstrates with water contact angle (WCA) of 158� and the sliding angle of about 6�

(Li et al. 2018).Niu et al. have fabricated Cu2O superhydrophobic surfaces on brass mesh via

spray deposition process which had a contact angle of 159.6� and a sliding angle of1� (Niu and Kang 2018). T. Ren et al. have developed novel highly transparent and

Fig. 4 (a–b) Optical images of superhydrophobic silica coating prepared after three dips, (Gurav etal. 2015) (c–d) water jet impact test on superhydrophobic RB-3 coating after 30 and 120 s and theircorresponding SEM images (Liu et al. 2015a)

Smart Nanocoating (Metal oxide and Composite) and its surface. . . 7

superhydrophobic coatings with extremely low bacterial adhesion and bactericidalperformance which were prepared by spray-coating hydrophobic silica sol and CuOnanoparticles (NPs). Superhydrophobic characteristics resulted in a reduction in theadhesion of bacteria (Escherichia coli, E. coli) by up to 3.2 log cells/cm.2 (Ren et al.2018). C. Liu et al. have fabricated the corrosion-resistant and superhydrophobiccerium (Ce) coating with micro/nano flower-like structure by a one-step electrode-position process. The coating exhibits superhydrophobicity with a contact angle of162� and a sliding angle less than 4� (Liu et al. 2014). A. Matin et al. have preparedsuperhydrophobic and superoleophobic surfaces on stainless steel meshby using cerium oxide (CeO2) nanoparticles. The coated meshes exhibited a highvalue of water CA �150�and a very low angle for the model oil, hexadecane, thatinstantaneously wetted the surface (Matin et al. 2018). X. P. Li et al have developedthe hydrophobic CeO2 nanomaterials was synthesised via hydrothermal methodwithout chemical modification with photocatalytic activity (Li et al. 2018b).

Composite-Based Coating

Composite coating with mixed oxide on the different substrate was developed withsuperhydrophobic functionality. G. R. T. Suyambulingam et al. has successfullydeveloped the superhydrophobic ZnO/CuSA2 thin films using spray-coatingmethod. The thinfilm coating was found to be with contact angle more than 151�

and exhibits enhanced superhydrophobic properties by increasing the weight per-centage of ZnO (Suyambulingam et al. 2017). G. He et al. have fabricated super-hydrophobic Zn/ZnO surfaces via electrodeposition which showed goodsuperhydrophobicity with a water contact angle (WCA) of 160� and a slidingangle of about 1� (He et al. 2018a). S. Qian et al. research group has developedthe micro/nanostructured ZnO-alkylamine composite films on carbon steel substrateusing electrodeposition and anodization process. The deposited film enabled surfacesuperhydrophobicity with the water contact angle (WCA) up to 158� when com-pared to the bare steel (WCA =73.7�) (Qian and Cheng 2018). G. He et al. havedeveloped the superhydrophobic (SHP) Zn/ZnO/TiO2 surfaces with dendritic struc-tures on Ti6Al4V substrate by chemical etching, electrodeposition, and followingannealing process. The wettability of the coated surface demonstrated excellent roll-off and self-cleaning properties with water contact angle (WCA) which was 160�

and the rolling angle was less than 1� (He et al. 2018b). Cheng et al. have fabricatedthe NiO/ZnO superhydrophobic surface on zinc substrate via chemical substitution/deposition and thermal annealing with water contact angle (WCA) of 153� and asliding angle (SA) of �5� without the use of any additional organic coating (Chenget al. 2017). Y. Cheng et al.’s research team also developed superhydrophobic CuZn5and AuZn3 alloys surface which has been fabricated on the copper substrate viaelectrochemical treatment, electroless chemical deposition, and annealing. Thesecoated surfaces shows outstanding superhydrophobicity with WCA of 170� andWSA about 0� without any organic modification (Cheng et al. 2018). M. Salehi et al.have developed the superhydrophobic Ni-TiO2/TMPSi nanocomposite coating using

8 P. S. Kumar and P. S. Moorthy

copper substrate. The nanocomposite coating shows the high water-repellency(WCA = 151.6� and SA = 6.2�) (Salehi et al. 2019). Y. Zhou et al. have fabricatedthe micro-posts structured Cu/Cr multilayer coating which was prepared by a simpletwo-step approach with water drop greater than 140� by optimizing the electrode-position time of Cr Zhou et al. 2013).

Surface Functionalization

Synthesized nanoparticles (NPs) were surface functionalized with different silanecompounds such as tetraethoxysilane, fluoroalkylsilanes (FAS), tridecafluoro-1,methyltriethoxysilane, chlorotrimethylsilane, 1, 2, 2-tetrahydrooctyldimethylchlorosilane, polydimethylsiloxane (PDMS), and methacryloxypropyltri-methoxysilane to enhance the superhydrophobic functionality. S. Liu et al. havedeveloped a novel raspberry-like superhydrophobic SiO2 coatings by simple con-densation of fluoroalkoxysilane. Coating surface exhibited a contact angle of 152�

and rolls off the surface at a sliding angle of 10� with the scratch of the applied forceof ~150 mN. Figure 4c, d shows the water jet impact test on superhydrophobic SiO2

RB-3 coating after 30 and 120 s and their corresponding SEM images. Similarly, asimple single-step sol-gel process was developed using a long-chain fluoroalk-ylsilane (FAS) to fabricate superhydrophobic coating on glass substrate. The FASbased coating shows a high contact angle of 169� with respect to a deposition time of300 s. However, the coatings prepared with a prolonged deposition time of 600 sshow the water contact angle (WCA) decreased to 143� and the sliding angleincreased to 15� (Liu et al. 2015a, b).

D. W. Li et al. have fabricated a robust superhydrophobic coating by spraying afluorine-free suspension composed of epoxy resin (EP), polydimethylsiloxane(PDMS), and modified SiO2 on various substrates. Coating exhibits a contactangle of 159.5� and a sliding angle of 3.8� (Fig. 5) (Li et al. 2019). X. Zhang et al.have fabricated the fluorine-free superhydrophobic polyethersulfone (PES) compos-ite coating enhanced by assembled MMT-SiO2 nanoparticles (NPs) via sol-gel withhigh water contact angle (WCA) ~ 156.1 � 1.1� and low sliding angle (SA) ~4.8 � 0.7� (Zhang et al. 2017a).

X. Zhang et al. have fabricated superhydrophobic coating by in situ growth ofnano-silica on polyethersulfone (PES) surface with a large water contact angle(WCA) of 157.2 � 1.3� and small sliding angle of 3 � 0.5�. After surface modifi-cation with 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (POTS), super-hydrophobic PES-PDA-SiO2-POTS coating was easily prepared by a simple one-step spraying method with less than 2.6 wt% SiO2 (Zhang et al. 2018). X. Zhang etal. have prepared the robust superhydrophobic epoxy (EP) -polytetrafluorethylene(PTFE)/graphene-polydopamine (GP) coating using SiO2 -1H, 1H, 2H, 2H -perfluorooctyltriethoxy silane (POTS). The coating was successfully prepared byelectrostatic spraying with WCA of the coating was around 156.3 � 1.5�and WSAwas around 3.5 � 0.5�. (Zhang et al. 2019c). Y. Qing et al. have prepared themodified TiO2 particles (FAS-TiO2) by hydrothermal reaction process with CA of

Smart Nanocoating (Metal oxide and Composite) and its surface. . . 9

160.6� and SA of 3.9�. FAS-TiO2/PDMS superhydrophobic sandpaper surface(FTPSS) exhibit excellent self-cleaning and anti-snow/anti-icing performance evenafter 50 abrasion cycles with sandpaper and prevented snow and ice from adhering tothe substrate (Qing et al. 2019). K. Chen et al. have reported the UV and pH dualstimuli-responsive self-repairing water-based superhydrophobic TiO2 coatingswhich were prepared by spray process using perfluorooctyltriethoxysilane (FAS13)with WCA of 155.3� (Chen et al. 2017). S. Liu et al. have fabricated polydopamineand TiO2 coatings on sand surfaces and subsequent hydrophobic modification(WCA ~153�) with low surface energy material (Liu et al. 2019).

Y. Zhang et al. have developed optically transparent superhydrophobic SiO2 filmswhich were synthesized by sol-gel method. Comparing with the 1, 1, 1, 3, 3, 3-hexamethyldisilazane (HMDS)-modified films (140 � 2�), the films modified bytrimethylchlorosilane (TMCS) showed very high water contact angle (164 � 2�),which indicates the excellent waterproof behavior of the films (Zhang et al. 2017b).S. G. Lee et al. have developed the SiO2-fluoropolymer hybrid nanoparticles (SFNs)on coated steel substrate by the spray-coating process. SFNs coating with water andhexadecane droplets have high contact angles of 163� and 151�, respectively (Leeet al. 2013).

Conclusion

In summary, the superhydrophobic surfaces have drawn a lot of interest in thecoating industry due to its multifunctional properties. Synthesized metal oxide andcomposite nanomaterials exhibit excellent superhydrophobic properties with selec-tive silane surface functionalization. Superhydrophobic coatings prepared by asimple, inexpensive sol-gel dip and spray-coating process are promising. However,the key issue to overcome is that the superhydrophobic coatings exhibit low adhe-sion/durability performance and low curing temperature for practical industrialapplications.

160

150

140

130

Con

tact

ang

le (

°)

Sliding angle (°) C

onta

ct a

ngle

(°)

Sliding angle (°)

120

110 0

4

8

12

16

20

0 20 40

a b

60 80 100 120Time (min)

160

120

80

40

0 0

10

20

30

40

50

60

0 10 20 30 40 50 60Time (min)

Fig. 5 (a–b): High- and low-temperature stability tests for superhydrophobic EP + PDMS@SiO2

coatings with contact angle and sliding angle with the function of immersion time (Li et al. 2019)

10 P. S. Kumar and P. S. Moorthy

References

Balgude D, Sabnis A (2012) Sol–gel derived hybrid coatings as an environment friendly surfacetreatment for corrosion protection of metals and their alloys. J Sol-Gel Sci Technol 64(1):124

Chen K, Gu K, Qiang S, Wang C (2017) Environmental stimuli-responsive self-repairingwaterbased superhydrophobic coatings. RSC Adv 7:543

Cheng Y, Lu S, Xu W, Boukherroub R, Szunerits S, Liang W (2017) Controlled fabrication of NiO/ZnO superhydrophobic surface on zinc substrate with corrosion and abrasion resistance.J Alloys Compd 723:225

Cheng Y, Lu S, Xu W, Cao K, Li J, Zheng Y (2018) Controllable fabrication of superhydrophobicalloys surface on copper substrate for self-cleaning, anti-icing, anti-corrosion and anti-wearperformance. Surf Coat Technol 333:61

Cheng Q, Cao D, Liu X, Zheng Y, Shi Z, Zhu S, Cui Z (2019) Superhydrophobic coatings with self-cleaning and antibacterial adhesion properties for denture base. J Mech Behav Biomed Mater98:148

Ebert D, Bhushan B (2012) Transparent, superhydrophobic, and wear-resistant coatings on glassand polymer substrates using SiO2, ZnO, and ITO nanoparticles. Langmuir 28:11391

Gao Y, Gereige I, Labban AE, Cha D, Isimjan TT, Beaujuge PM (2014) Highly transparent and UV-resistant superhydrophobic SiO2-coated ZnO nanorod arrays. ACS Appl Mater Interfaces64:2219

Gurav AB, Xu Q, Latthe SS, Vhatkar RS, Liu S, Yoon H, Yoon SS (2015) Superhydrophobiccoatings prepared from methyl-modified silica particles using simple dip-coating method.Ceram Int 41:3017

He G, Lu S, XuW, Yea P, Liu G, Wang H, Dai T (2018a) Stable superhydrophobic Zn/ZnO surfacesfabricated via electrodeposition on tin substrate for self-cleaning behavior and switchablewettability J Alloys Compd 747:772

He G, Lu S, Xu W, Yu T, Li J, Dai T (2018b) Durable superhydrophobic Zn/ZnO/TiO2 surfaces onTi6Al4V substrate with self-cleaning property and switchable wettability. Ceram Int 44:638

Hooda A, Goyat MS, Gupta R, Prateek M, Agrawal M, Biswas A (2017) Synthesis of nano-texturedpolystyrene/ZnO coatings with excellent transparency and superhydrophobicity. Mater ChemPhys 193:447

Jeevaham J, Chandrasekaran M, Joseph GB, Durairaj RB, Mageshwaran G (2018) Super-hydrophobic surfaces: a review on fundamentals, applications, and challenges. J Coat TechnolRes 15:231

Kumar PS, Sundaramurthy J, Mangalaraj D, Nataraj D, Rajarathnam D, Srinivasan MP (2011a)Enhanced super-hydrophobic and switching behavior of ZnO nanostructured surfaces preparedby simple solution – immersion successive ionic layer adsorption and reaction process. J ColloidInterface Sci 363:51

Kumar PS, Dhayal Raj A, Mangalaraj D, Nataraj D, Ponpandian N, Li L, Chabrol G (2011b)Growth of hierarchical based ZnO micro/nanostructured films and their tunable wettabilitybehavior. Appl Surf Sci 257:6678

Kumar PS, Sundaramurthy J, Zhang X, Mangalaraj D, Thavasi V, Ramakrishna S (2013) Super-hydrophobic and antireflecting behavior of densely packed and size controlled ZnO nanorods. JAlloys Compd 553:375

Latthe SS, Sutar RS, Kodag VS, Bhosale AK, Kumar AM, Sadasivuni KK, Xing R, Liu S (2019)Self – cleaning superhydrophobic coatings: potential industrial applications. Prog Org Coat128:52

Lee SG, Ham DS, Lee DY, Bong H, Cho K (2013) Transparent superhydrophobic/translucentsuperamphiphobic coatings based on silica–fluoropolymer hybrid nanoparticles. Langmuir29:15051

Lee KM, Park H, Kim J, Chun DM (2019) Fabrication of a superhydrophobic surface using a fuseddeposition modeling (FDM) 3D printer with poly lactic acid (PLA) filament and dip coatingwith silica nanoparticles. Appl Surf Sci 467–468:979

Smart Nanocoating (Metal oxide and Composite) and its surface. . . 11

Li J, Wu R, Jing Z, Yan L, Zha F, Lei Z (2015) One-Step Spray-Coating Process for the Fabricationof Colorful Superhydrophobic Coatings with Excellent Corrosion Resistance. Langmuir 31(39):10702.

Li H, Yu S, Hu J (2018a) A robust superhydrophobic Zn coating with ZnO nanosheets on steelsubstrate and its self-cleaning property. Thin Solid Films 666:100

Li XP, Sun YL, Luo CW, Chao ZS (2018b) UV-resistant hydrophobic CeO2 nanomaterial withphotocatalytic depollution performance. Ceram Int 44:13439

Li DW, Wang HY, Liu Y, Wei DS, Zhao ZX (2019) Large-scale fabrication of durable and robustsuperhydrophobic spray coatings with excellent repairable and anticorrosion performance.Chem Eng J 367:169

Liu C, Su F, Liang J, Huang P (2014) Facile fabrication of superhydrophobic cerium coating withmicro-nano flower-like structure and excellent corrosion resistance. Surf Coat Technol 258:580

Liu S, Latthe SS, Yang H, Liu B, Xing R (2015a) Raspberry-like superhydrophobic silica coatingswith self-cleaning, properties. Ceram Int 41:11719

Liu S, Liu X, Latthe SS, Gao L, An S, Yoon SS, Liu B, Xing R (2015b) Self-cleaning transparentsuperhydrophobic coatings through simple sol–gel processing of fluoroalkylsilane. Appl SurfSci 351:897

Liu S, Cai T, Shen X, Huang E, Wang Z, Sun Q (2019) Superhydrophobic sand with multi-functionalities by TiO2-incorporated mussel-inspired polydopamine. Ceram Int

Mahadik SA, Parale V, Vhatkara RS, Mahadik DB, Kavale MS, Wagh PB, Gupta S, Gurav J (2013)Superhydrophobic silica coating by dip coating method. Appl Surf Sci 277:67

Mahltig B, Grethe T, Haase H (2016) Antimicrobial coatings obtained by sol–gel method. In:Handbook of sol-gel science and technology. Springer, Cham, pp 1–27

Matin A, Baig U, Gondal MA, Akhtar S, Zubair SM (2018) Superhydrophobic and superoleophilicsurfaces prepared by spray-coating of facile synthesized cerium(IV) oxide nanoparticles forefficient oil/water separation. Appl Surf Sci 462:95

Movahedi T, Norouzbeigi R (2019) Synthesis of flower-like micro/nano ZnO superhydrophobicsurfaces: additive effect optimization via designed experiments. J Alloys Compd 795:483

Nishimoto S, Bhushan B (2013) Bioinspired self-cleaning surfaces with superhydrophobicity,superoleophobicity, and superhydrophilicity. RSC Adv 3:671

Niu L, Kang Z (2018) Spray deposition process to fabricate Cu2O superhydrophobic surfaces onbrass mesh for efficient oil-water separation. Mater Lett 210:97

Park J, Shin K, Lee C (2016) Int J Pr Eng Man 17:1Qian S, Cheng YF (2018) Fabrication of micro/nanostructured superhydrophobic ZnO-alkylamine

composite films on steel for high-performance self-cleaning and anti-adhesion of bacteriaColloids Surf A Physicochem Eng Asp 544:35

Qing Y, Long C, An K, Hu C, Liu C (2019) Sandpaper as template for a robust superhydrophobicsurface with self-cleaning and anti-snow/icing performances. J Colloid Interface Sci 548:224

Ren T, Yang M, Wang K, Zhang Y, He J (2018) CuO nanoparticles-containing highly transparentand superhydrophobic coatings with extremely low bacterial adhesion and excellent bactericidalproperty. ACS Appl Mater Interfaces 10:25717

Salehi M, Mozammel M, Emarati SM (2019) Superhydrophobic and corrosion resistant propertiesof electrodeposited Ni-TiO2/TMPSi nanocomposite coating. Colloids Surf A Physicochem EngAsp 573:196

Shang H, Wang Y, Limmer SJ, Chou TP, Takahashi K, Cao GZ (2005) Optically transparentsuperhydrophobic silica-based films. Thin Solid Films 472:37

Suyambulingam GRT, Jeyasubramanian K, Mariappan VK, Veluswamy P, Ikeda H,Krishnamoorthy K (2017) Excellent floating and load bearing properties of superhydrophobicZnO/copper stearate nanocoating. Chem Eng J 320:468

Wang B, Zhang Y, Shi L, Lib J, Guo Z (2012) Advances in the theory of superhydrophobic surfaces.J Mater Chem 22:20112

Wu X, Wyman I, Zhang G, Lin J, Liu Z, Wang Y, Hu H (2016) Preparation of superamphiphobicpolymerbased coatings via spray- and dip-coating strategies. Prog Org Coat 90:463

12 P. S. Kumar and P. S. Moorthy

Wu Y, Krishnan P, Zhang MH, Yu LE (2018) Using photocatalytic coating to maintain solarreflectance and lower cooling energy consumption of buildings. Energ Buildings 164:176

Zhang M, Feng S, Wang L, Zheng Y (2016) Lotus effect in wetting and selfcleaning. Biotribology5:31

Zhang X,Wang H, Liu Z, Zhu Y, Wu S, Wang C, Zhu Y (2017a) Fabrication of durable fluorine-freesuperhydrophobic polyethersulfone (PES) composite coating enhanced by assembled MMT-SiO2 nanoparticles. Appl Surf Sci 396:1580

Zhang Y, Dong B, Wang S, Zhao L, Wan L, Wang E (2017b) Mechanically robust, thermally stable,highly transparent superhydrophobic coating with low-temperature sol–gel process. RSC Adv7:47357

Zhang X, Liu Z, Zhang X, Li Y, Wang H, Wang J, Zhu Y (2018) High-adhesive superhydrophobiclitchi-like coatings fabricated by in-situ growth of nano-silica on polyethersulfone surface.Chem Eng J 343:699

Zhang C, Kalulu M, Sun S, Jiang P, Zhou X, Wei Y, Jiang Y (2019a) Environmentally safe, durableand transparent superhydrophobic coating prepared by one-step spraying. Colloids Surf APhysicochem Eng Asp 570:147

Zhang Y, Zhang L, Xiao Z, Wang S, Yu X (2019b) Fabrication of robust and repairable super-hydrophobic coatings by an immersion method. Chem Eng J 369:1

Zhang X, Liu Z, Li Y, Wang C, Zhu Y, Wang H, Wang J (2019c) Robust superhydrophobic epoxycomposite coating prepared by dual interfacial enhancement. Chem Eng J 371:276

Zhou Y, Hang T, Li F, Li M (2013) Anti-wetting Cu/Cr coating with micro-posts array structurefabricated by electrochemical approaches. Appl Surf Sci 271:369

Smart Nanocoating (Metal oxide and Composite) and its surface. . . 13