Coating of Zno Nanoparticle on Cotton Fabric to Create a Functional Textile with Enhanced Mechanical Properties

polymers

Article Coating of ZnO Nanoparticle on Cotton Fabric to Create a Functional Textile with Enhanced Mechanical Properties

Imana Shahrin Tania 1,2,* and Mohammad Ali 1,*

1 Department of Mechanical Engineering, Bangladesh University of Engineering & Technology (BUET), Dhaka 1000, Bangladesh 2 Department of Wet Process Engineering, Bangladesh University of Textiles (BUTEX), Dhaka 1208, Bangladesh * Correspondence: [email protected] (I.S.T.); [email protected] (M.A.)

Abstract: The goal of this research is to develop a functional textile with better mechanical properties. Therefore, nano ZnO is synthesized, characterized, and applied to cotton fabric by mechanical thermo-fixation techniques. The synthesized nanoparticles are characterized by SEM and XRD analysis. The ZnO nanoparticle alone, ZnO nanoparticle with a binder, and ZnO with a binder and wax emulsion are then applied on cotton woven fabrics using three different recipes. The surface morphology of the treated fabric is studied using SEM and EDS. Antimicrobial activity, UV protection property, and crease resistance are all tested for their functional characteristics. In addition, all vital mechanical characteristics are assessed. The results suggest that using only nano ZnO or nano ZnO with a binder enhances functional features while deteriorating mechanical capabilities. Nano ZnO treatment with the third recipe, which includes the addition of an emulsion, on the other hand, significantly enhances mechanical and functional characteristics. Consequently, this study provides information to optimize the confidence of textile researchers and producers in using nano ZnO and understanding its features in key functional fabrics.

Citation: Tania, I.S.; Ali, M. Coating Keywords: ZnO nanoparticles; binder; mechanical properties; polyethylene wax emulsion; cot- of ZnO Nanoparticle on Cotton ton fabric Fabric to Create a Functional Textile with Enhanced Mechanical Properties. Polymers 2021, 13, 2701. https:// doi.org/10.3390/polym13162701 1. Introduction Nanoscience and nanotechnology is a rapidly evolving interdisciplinary ﬁeld that Academic Editor: Kyung-Wha Oh is being hailed as a new industrial revolution for the textile industry [1,2]. According to the national nanotechnology initiative (NNI), nanotechnology is characterized as using Received: 18 June 2021 structures with at least one dimension of nanometer-scale for the construction of materials, Accepted: 18 July 2021 Published: 13 August 2021 devices, or systems with novel or signiﬁcantly improved properties due to their nano- sizes [3,4]. The chemical and physical properties of a material change from the bulk to the

Publisher’s Note: MDPI stays neutral nanometer scale. Therefore, a nanoparticle shows more reactivity and some other unique with regard to jurisdictional claims in properties because of its high surface area to its volume ratio [5,6]. Nanotechnology is published maps and institutional affil- being more widely used as a result of its enormous economic potential [7]. The textile iations. sector is also advancing by applying the numerous benefits of nanoparticles. Moreover, the consumer demand for long-lasting and sustainable practical clothing has opened the door for nanomaterials to be used in textiles [1]. The specific benefits of different nanoparticles are used in the textile field to manufacture advanced textiles in the functional and clothing sections. Several studies are being conducted to develop multifunctional textile Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. materials that are coated with different nanoparticles. Nanoparticles such as silver (Ag), This article is an open access article zinc oxide (ZnO), titanium dioxide (TiO2), and silicon dioxide (SiO2) have been used by distributed under the terms and researchers to impart functional property and meet the demand of modern markets [8–10]. conditions of the Creative Commons For instance, a textile with high antibacterial activity was produced by utilizing the po- Attribution (CC BY) license (https:// tentiality of silver nanoparticles [11–13]. More functional properties, such as ultraviolet creativecommons.org/licenses/by/ protection, stain release, and antifungal activity, were achieved using TiO2 nanoparticles on 4.0/). textile fabric [14,15]. Other critical studies have been carried out to obtain multifunctional

Polymers 2021, 13, 2701. https://doi.org/10.3390/polym13162701 https://www.mdpi.com/journal/polymers Polymers 2021, 13, 2701 2 of 16

properties, such as self-cleaning, antimicrobial, antistatic, flame retardant, easy-care, UV defense, and water repellency [14,16–19]. However, ZnO nanoparticles have been found harmless and chemically stable during high temperatures exposing and photocatalytic oxidation [20,21]. Moreover, they have been highly attractive because of other remarkable potential applications in sunscreens, UV absorbers, anti-reflection coatings, photocatalysis, catalyst, solar cells, sensors, displays, piezoelectric devices, electro-acoustic, transducers, photodiodes, and UV light-emitting devices [8,22]. Moreover, they are a comparatively safe and inexpensive material that can be directly used for biomedical applications [23]. Due to these excellent properties of ZnO nanoparticles, much effort has been directed to the fabrication of ZnO with interesting morphologies and assemblies [24–26]. Furthermore, various methods are also used to apply ZnO nanostructures on textile materials, such as the hydrothermal route [27], ul- trasonic irradiation technique, layer-by-layer deposition, pad-dry procedure, and sol–gel process [28–30]. Among many encouraging works related to the use of ZnO nanoparticles in the textile sector, there are also some limitations. Nano ZnO treatment on cotton fabric shows the degradation of its mechanical performance. Our recent paper revealed the degradation of tensile and tearing strength of woven fabric on both warp and weft directions owing to ZnO nano deposition [31]. Arputharaj [32] reported that ZnO nano-treated cotton fabric showed a 5.43% reduction in tensile strength for the warp direction. The nanoparticle type, treatment process, and fiber modification system are generally responsible for degrading important mechanical properties. Subash et al. [33] investigated the antimicrobial activity of ZnO nano-treated fabric, and they reported that the treated fabric showed excellent antibacterial activity against Gram-positive and Gram-negative bacteria.Nevertheless, this treatment lowered the essential mechanical characteristics, such as tensile strength, tearing strength, and abrasion resistance. Other related works of nano ZnO treatment on cotton fabric also reported similar reduction in the mechanical properties of textile fabric after using ZnO nanoparticles [4,34]. The wash durability of ZnO nano-treated fabric is also another challenging issue for nanoparticle researchers [35]. These issues may be the most significant impediment to using ZnO nanoparticles on cotton fabric. In this regard, chemical and auxiliaries employment may be emphasized to alleviate these challenges and increase nano deposition quality. As the mechanical property of the fabric deteriorates, it is necessary to use a chemical that provides smoothness, softness, and flexible handling qualities to the fabric. We know that fabric mobility [36] linked to the qualities listed is crucial in improving mechanical properties. The mentioned characteristics and a low friction coefficient ensure the uniform distribution of applied force across the whole fabric [37,38], resulting in improved mechanical performance [37,38]. Herein, a polyethylene wax emulsion is utilized to provide all outstanding smoothness and a soft handle to the fibers. From the supporting literature and technical data sheet [39], it is found that the wax emulsion, JinlubEco NP-825N (brand name), has extra lubrication and slippery effects and reduces the coefficient of friction. Further, it improves abrasion resistance and mechanical strength, thus increasing the weave and knitting productivity of yarns. This is the context for using polyethylene wax emulsion (JinlubEco NP-825N) combined with ZnO nanoparticles and a binder to increase fabric quality after nano ZnO deposition. Additionally, the analysis of the essential physical properties of nano ZnO-treated fabric has not been well defined by the investigation of others. The mechanical properties are significant for cotton fabric related to the durability and serviceability of the textile. Furthermore, the improved mechanical properties play an essential role against various stresses and tension created on the fabric surface during coloration, finishing, cutting, sewing, and practical uses. Moreover, the comfortability and handling properties are also related to the stiffness of the fabric. Wrinkle recovery is regarded as a different functional quality and associated with the easy-care property of the fabric. The present study provides compiled and useable information regarding the above mechanical properties of nano ZnO-coated cotton fabric. Polymers 2021, 13, x FOR PEER REVIEW 3 of 16

provides compiled and useable information regarding the above mechanical properties of Polymers 2021, 13, 2701 nano ZnO-coated cotton fabric. 3 of 16 Zinc oxide nanoparticles are combined with auxiliary chemicals to obtain the optimal functional and mechanical qualities. A surfactant is also used in all recipes to reduce the surface Zinctension oxide of water nanoparticles and increase are combined the wetta withbility auxiliary and hydrophilicity chemicals to of obtain the fabric. the optimal Us- ingfunctional a binder and and a mechanicalwax emulsion qualities. for the immobi A surfactantlization is of also ZnO used nanoparticles in all recipes is a tounique reduce ideathe for surface improving tension the of mechanical water and increaseproperties the of wettability cotton fabric. and hydrophilicityAt the same time, of the it can fabric. createUsing greater a binder attention and a waxfrom emulsion textile manufa for thecturers immobilization and eventually of ZnO show nanoparticles a new dimension is a unique foridea quality for fabric. improving the mechanical properties of cotton fabric. At the same time, it can create greater attention from textile manufacturers and eventually show a new dimension 2. Experimentalfor quality fabric. Section 2.1. Materials 2. Experimental Section The fabric of 100% cotton with a plain weave structure is collected from a local in- 2.1. Materials dustry with 80 ends per inch (EPI) and 75 picks per inch (PPI), while the areal density is 168 g/m².The The fabric raw ofcotton 100% fabric cotton is withthen scoured a plain weave and bleached structure before is collected nano-coating from a to local im- in- partdustry absorbency with 80 and ends permanent per inch (EPI) whiteness. and 75 picksThe chemical per inch (PPI),zinc sulfate while theheptahydrate areal density is 168 g/m2. The raw cotton fabric is then scoured and bleached before nano-coating to (ZnSO4 • 7H2O, 99% purity) for synthesis is purchased from Merck Life Science Private impart absorbency and permanent whiteness. The chemical zinc sulfate heptahydrate Ltd., Mumbai, India. Ethanol and sodium hydroxide are purchased from Sigma Aldrich, (ZnSO • 7H O, 99% purity) for synthesis is purchased from Merck Life Science Private Taufkirchen,4 Germany.2 Pretreatment chemicals: wetting agent, sequestering agent, deter- Ltd., Mumbai, India. Ethanol and sodium hydroxide are purchased from Sigma Aldrich, gent, caustic soda, and hydrogen peroxide are collected from Orient Chemical Ltd., Taufkirchen, Germany. Pretreatment chemicals: wetting agent, sequestering agent, deter- Dhaka,Bangladesh. Polyethylene wax emulsion (brand name: Jinlub Eco NP-825N, char- gent, caustic soda, and hydrogen peroxide are collected from Orient Chemical Ltd., Dhaka, acter: softener, nonionic, yellowish liquid, water-soluble,) is collected from Jintex, Taiwan. Bangladesh. Polyethylene wax emulsion (brand name: Jinlub Eco NP-825N, character: soft- A binder called OB-45 (nature: thermally cross-linkable, aqueous acrylate dispersion; ap- ener, nonionic, yellowish liquid, water-soluble,) is collected from Jintex, Taiwan. A binder pearance: low viscosity white milky liquid) is collected from Fortune top Pte Ltd. New called OB-45 (nature: thermally cross-linkable, aqueous acrylate dispersion; appearance: Taipei City, Taiwan. Tubingen Chemicals, Comilla, Bangladesh, supplies a surfactant low viscosity white milky liquid) is collected from Fortune top Pte Ltd. New Taipei City, named Jingen DT HLF-18. Taiwan. Tubingen Chemicals, Comilla, Bangladesh, supplies a surfactant named Jingen DT HLF-18. 2.2. Synthesis of ZnO Nanoparticles 2.2.The Synthesis experimental of ZnO setup Nanoparticles of ZnO nanoparticle synthesis is shown in Figure 1. The wet chemicalThe process experimental is applied setup for ofthe ZnO synthesis nanoparticle by following synthesis the is method shown inused Figure by 1Kawano. The wet andchemical Imai [40] process with some is applied modifications. for the synthesis An aqueous by followingsolution of the 0.2 methodM zinc sulfate used by (ZnSO Kawano4) is madeand Imai from [40 zinc] with sulfate some heptahydrate modiﬁcations. (ZnSO An aqueous4 • 7H2O) solution in de-ionized of 0.2 M water. zinc sulfate A 25 mL (ZnSO of 4) 0.2is M made NaOH from (pH zinc = 3.8) sulfate solution heptahydrate is prepared (ZnSO separately4 • 7H 2withO) in purified de-ionized water. water. The Areaction 25 mL of is then0.2 M performed NaOH (pH by = slowly 3.8) solution dropping is prepared NaOH into separately the ZnSO with4 solution. puriﬁed water.The bath The is reaction placed is on thena magnetic performed stirrer by for slowly 30 min dropping and kept NaOH for 4 into h at the 60 ZnSO°C temperature.4 solution. TheThe bathnanoparticles is placed on area obtained magnetic by stirrer centrifuging for 30 min and and drying kept after for 4 washing. h at 60 ◦C temperature. The nanoparticles are obtained by centrifuging and drying after washing.

Figure 1. Experimental setup for the synthesis of ZnO nanoparticles. 2.3. Characterization of Nanoparticles The synthesized nanoparticles are characterized by high-resolution scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. A ﬁeld emission electron Polymers 2021, 13, x FOR PEER REVIEW 4 of 16

Figure 1. Experimental setup for the synthesis of ZnO nanoparticles.

2.3. Characterization of Nanoparticles The synthesized nanoparticles are characterized by high-resolution scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. A field emission electron microscope, JSM-6700F, Tokyo, Japan, determines the features, surface characteristics, and approximate size of the discrete nanoparticles. The sputtering device (Jeol JFC-1600 auto fine coater, Japan) creates a 75 nm thin platinum layer on our non-conductive cotton fabric in a vacuum environment before SEM analysis. Figure 2a shows the individual nanoparticle Polymers 2021, 13, 2701in various sizes and shapes in ×50,000 magnification. From this image, the size measuring 4 of 16 software detects the approximate size of the nanoparticle. SEM analysis involves bombarding the surface of a sample with an intensely focused scanning electron beam generating a large number of secondary electrons whose strength is influenced by surface to- microscope, JSM-6700F, Tokyo, Japan, determines the features, surface characteristics, and pography [11]. Particles of various shapes and diameters are visible in the SEM images. approximate size of the discrete nanoparticles. The sputtering device (Jeol JFC-1600 auto The X-ray diffractometer obtains the crystalline shape and size: Phillips, X’pert PRO, Hol- fine coater, Japan) creates a 75 nm thin platinum layer on our non-conductive cotton fabric land. Figure 2bin shows a vacuum the environmentXRD pattern beforeof the SEM ZnO analysis. nanoparticles. Figure2 Thea shows measurement the individual is nanoparticle carried out at ain scanning various rate sizes of and 8°/min shapes in a in2θ× range50,000 of magnification. 20–80°, using the From Debye–Scherrer this image, the size measur- formula as Equationing software (1) detects the approximate size of the nanoparticle. SEM analysis involves bombarding theParticle surface Size of a= sample(0.9 × λ)/(d with cos anθ) intensely focused scanning(1) electron beam generating a large number of secondary electrons whose strength is influenced by surface where λ = 1.54060topography Å(Angstrom) [11]., Particles0.9 × λ = of1.38654 various Å, shapesθ = 2θ/2, and and diameters d = the full are width visible at in the the SEM images. half maximum Theintensity X-ray ofdiffractometer the peak. obtains the crystalline shape and size: Phillips, X’pert PRO, Hol- This equationland. shows Figure that2b the shows calculated the XRD mean pattern size ofof thethe ZnO nanoparticle nanoparticles. is The70 (±5) measurement is

nm. The peaks carriedof the XRD out at pattern a scanning are obtained rate of 8◦ at/min 2θ = in 31.6 a 2θ°,range 34.3°, of 36.1°, 20–80 47.43°,◦, using 56.52°, the Debye–Scherrer 62.77°, 67.9°, 72.1°,formula and as76.98° Equation corresponding (1) to the lattice planes (100), (002), (101), (102) (200), (112), (201) (004), and (202), respectively,Particle which Size indicate = (0.9 × theλ)/(d obvious cosθ) formation of (1) the ZnO nanoparticle. Our results strongly correlated with the standards (JCPDS) card file λ × λ θ θ no-036–1451 forwhere ZnO nanoparticles= 1.54060 Å(Angstrom), [41]. Similar 0.9 peaks= of 1.38654 ZnO Å,nano=particles 2 /2, and are d also = the full width at found by the investigationsthe half maximum of Sing intensity et al. [42]. of the peak.

Figure 2. (aFigure) SEM (scanning2. (a) SEM electron (scanning microscope) electron micr imagesoscope) of ZnO images nanoparticles of ZnO nanoparticles in ×50,000 magniﬁcation in ×50,000 magnifi- with size; (b) XRD (X-ray diffraction)cation with pattern size; ZnO (b) XRD nanoparticles. (X-ray diffraction) pattern ZnO nanoparticles.

2.4. Application of ZnOThis Nanoparticles equation shows that the calculated mean size of the ZnO nanoparticle is 70 (±5) θ ◦ ◦ ◦ ◦ ◦ Mechanicalnm. thermo-fixation The peaks of is the used XRD to patternadhere nanoparticles are obtained at to 2 cotton= 31.6 fabric, 34.3 (pad-dry-, 36.1 , 47.43 , 56.52 , 62.77◦, 67.9◦, 72.1◦, and 76.98◦ corresponding to the lattice planes (100), (002), (101), (102) cure). Three distinct coating formulations containing the same quantity of nanoparticles (200), (112), (201) (004), and (202), respectively, which indicate the obvious formation of and a surfactant are employed. Firstly, the fabric is coated with a 1% ZnO nanoparticle, the ZnO nanoparticle. Our results strongly correlated with the standards (JCPDS) card ﬁle denoted by the sample name NanoZnO-1. For the second coating, 1% ZnO nanoparticle no-036–1451 for ZnO nanoparticles [41]. Similar peaks of ZnO nanoparticles are also found solution and a binder are produced by stirring continuously for 10 min, and the resulting by the investigations of Sing et al. [42].

2.4. Application of ZnO Nanoparticles Mechanical thermo-ﬁxation is used to adhere nanoparticles to cotton fabric (pad-dry- cure). Three distinct coating formulations containing the same quantity of nanoparticles and a surfactant are employed. Firstly, the fabric is coated with a 1% ZnO nanoparticle, denoted by the sample name NanoZnO-1. For the second coating, 1% ZnO nanoparticle solution and a binder are produced by stirring continuously for 10 min, and the resulting coated fabric is designated as a sample: NanoZnO-2. Finally, 1% ZnO nanoparticles, 10 g/L wax emulsion, and 1% binder are combined with propanol solution and stirred for 15 min at 60 ◦C. NanoZnO-3 is the sample name for the fabric coated with the third solution. Here, 73% pick-up is maintained throughout the padding, and the drying and curing conditions are 90 ◦C for 10 min and 150 ◦C for 5 min, respectively, resulting in the Polymers 2021, 13, x FOR PEER REVIEW 5 of 16

coated fabric is designated as a sample: NanoZnO-2. Finally, 1% ZnO nanoparticles, 10 Polymers 2021, 13, 2701 g/L wax emulsion, and 1% binder are combined with propanol solution and stirred for5 of 15 16 min at 60 °C. NanoZnO-3 is the sample name for the fabric coated with the third solution. Here, 73% pick-up is maintained throughout the padding, and the drying and curing conditions are 90 °C for 10 min and 150 °C for 5 min, respectively, resulting in the thermal thermalfixation ﬁxationof ZnO nanoparticles of ZnO nanoparticles into the intofabric. the The fabric. diagram The diagram of the thermo-fixation of the thermo-ﬁxation method method[43] for nanoparticle [43] for nanoparticle application application is shown is in shown Figure in 3. Figure 3.

Figure 3.3. The sequence of thermo-ﬁxationthermo-fixation coatingcoating ofof nanoparticlesnanoparticles onon thethe fabricfabric surface.surface. 2.5. Measurements and Analysis 2.5. Measurements and Analysis The following measurements are carried out to analyze functional and mechanical The following measurements are carried out to analyze functional and mechanical properties: UV protection, antimicrobial activity, crease resistance, tensile strength, tearing properties: UV protection, antimicrobial activity, crease resistance, tensile strength, tear- strength, elongation, bending length, and frictional coefﬁcient. ing strength, elongation, bending length, and frictional coefficient. 2.5.1. Evaluation of Ultraviolet (UV) Protection 2.5.1. Evaluation of Ultraviolet (UV) Protection There are three categories of UV radiation of solar light: (i) UV-A of wavelength 320–400There nm, are (ii) three UV-B categories of 280–320 of nm, UV andradiatio (iii)n UV-C of solar of 200–280 light: (i) nm. UV-A The of UV-A wavelength rays are 320– the least400 nm, harmful; (ii) UV-B the UV-B of 280–320 rays are nm, the and more (iii) powerful UV-C andof 200–280 harmful nm. form The of radiation,UV-A rays and are they the areleast the harmful; most common the UV-B cause rays ofare sunburn, the more aging, powerful wrinkling, and harmful and skin form cancer. of radiation, The UV-C and raysthey areare thethe shortestmost common and the cause most of harmful, sunburn, but, aging, fortunately, wrinkling, most and of themskin cancer. are absorbed The UV- by theC rays atmosphere’s are the shortest ozone and layer. the Therefore, most harmful, the concerning but, fortunately, regions most for theof them evaluation are absorbed of sun protectionby the atmosphere’s arise on UV-A ozone and layer. UV-B Therefore, regions [ 44the]. Protectionconcerning against regions the for harmful the evaluation effects ofof UVsun raysprotection by using arise functional on UV-A textile and UV-B material region iss an [44]. appreciable Protection way against to prevent the harmful skin cancereffects orof otherUV rays related by using skin functional diseases caused textile bymaterial the UV is raysan appreciable of the Sun way [45]. to Textile prevent fabric skin gives can- protectioncer or other by related absorbing skin anddiseases blocking caused the by penetration the UV rays of UVof the rays Sun [46 [45].]. The Textile UV protection fabric gives of ourprotection treated by and absorbing untreated and fabric blocking is measured the pene bytration the PerkinElmer of UV rays UV [46]. visible The UV machine protection from theof our USA, treated model-LAMBDA and untreated 1050+. fabric Thisis measured instrument by the provides PerkinElmer the transmittance UV visible curvemachine of everyfrom the sample. USA, By model-LAMBDA analyzing the transmittance 1050+. This in curve,strument the UVprovides protection the transmittance power is evaluated. curve of every sample. By analyzing the transmittance curve, the UV protection power is eval- 2.5.2.uated. Analysis of Antimicrobial Activity The antimicrobial activity of nano-treated and untreated fabric is quantitatively eval- uated2.5.2. Analysis by the standard of Antimicrobial test method Activity [47]. The study is performed against Gram-positive S. aureusThe antimicrobialand Gram-negative activityE. of coli nano-treatedby the colony and countinguntreated method, fabric is quantitatively and the results eval- are expresseduated by the by standard a bacterial test reduction method [47]. percentage The study (R%). is performed For this test, against the number Gram-positive of viable S. speciesaureus and in suspension Gram-negative is estimated, E. coli by and the the colony percentage counting reduction method, is measuredand the results based are on ex- re- coveriespressed by from a bacterial the untreated reduction sample. percentage This approach (R%). isFor intended this test, for the a surfacesnumber withof viable 50–100% spe- reductioncies in suspension capacity is for estimated, the required and contact the perc timeentage [48 ].reduction The following is measured formula based calculates on recov- the percenteries from of bacteriathe untreated killed withinsample. the This designated approach time is intended in Equation for a (2): surfaces with 50–100% The bacterial reduction percentage

No − Nt (R%) = × 100 (2) No Polymers 2021, 13, 2701 6 of 16

No = number of colonies in control and Nt = number of colonies after the selected hour of introducing samples. Here, the samples are tested both after 1 h and 24 h of contact time.

2.5.3. Crease Resistance A crease is a broken line, mark, or fold on a fabric caused by sharp folding. It is formed when the fabric is distorted so that part of it is stretched beyond its elastic recovery [49]. Crease resistance is a property of fabric that prevents fabric from creasing and is generally measured by the recovery angle of the fabric after creasing. A higher angle of recovery indicates more resistance to the crease. Thus, it is a quantitative measurement of the easy- Polymers 2021, 13, x FOR PEER REVIEWcare property of the fabric. In the current research, the crease recovery angle of untreated7 of 16 and treated fabric is measured using the AATCC standard test method [50].

2.5.4. Mechanical Properties ± 3 (averageThe tensile UPF strengthranges), indicating is measured that by we the discovered ISO 13934-1:2013 outstanding test UV method, protection. and tearing When allstrength of the isdata measured in Table by 1 are ISO13937-2:2000. compared, it is Theclear Titan that Universalthe ZnO nano-coating Strength Tester can ofincrease James theHeal UV is usedprotection for the of test. cotton Measurements fabric. are performed in both the warp and weft directions of theSignificant fabrics. Average improvements values are have obtained been made from theby using measurements a binder ofas threea fixing samples. agent for Fabric the depositionstiffness expressed of nanoparticles. by bending In addition, length is determinedZnO has a well-defined by ASTM D1388 sun protection using the Shirleypower [45,54]stiffness and tester. is capable The frictional of reflecting property both is UV-A measured (320–400 by the nm) Fabric and UV-B Touch (280–320 Tester of nm) SDL wave- Atlas, lengthsUSA. All of experimental sunlight [55]. samples As a result, areconditioned the coated fabric in the in standard this study, atmosphere which is atmade 20 ± up5 ◦ ofC nanoand 65 ZnO± 2% particles relative measuring humidity 70 for nm 12 (about), h in a conditioning exhibits strong laboratory resistance before to UV every light test. blocking. However, our findings are consistent with the previous investigation of nano ZnO on fabric.3. Results Yuwanda and Discussion and Punnama [56] used poly 4-styrenesulfonic acid to immobilize ZnO nanoparticles3.1. Assessment on of Ultravioletcotton fabrics (UV) and Protection obtained similar UV protection. Likewise, AS/NZS 4399 Ultravioletdefined three protection levels of protection: is assessed excellent, by the UV very transmittance good, and good curve [57], of untreatedwhich are also and listedtreated in fabric Table measured 1 for our usingworking a UV samples. visible spectrophotometerFinally, it should be by noted selecting that aour wavelength result of significantlyregion of 200–700 improved nm. TheUV protection obtained results of cotton are fabric presented is the inattribute Figure 4ofa. the The shielding curve clearly effect ofshows ZnO the nanoparticles amount of transmittance[56]. However, in percentagethe two auxiliary by treated chemical and untreated binders and fabrics. wax The emul- ap- sionproximate used in quantitative this study valuehave a of minor transmittance impact on is listedUV protection, in Table1 based as it is on found the transmittance from Figure 4bcurve. that Thethe samples typical UPF with (ultraviolet the binder protection(S-B) only factor)and the ranges binder are with also an presented emulsifier in (S-B@E)Table1, demonstratewhich are determined minimal changes by following in UV transmittance the literature (T%) [51] andthan the that standard of the untreated AS/NZS fabric. 4399. TheIt is foundbinder thatonly the increases untreated the fabric nano transmitted deposition; about therefore, 60% ofthe UV samples light at NanoZnO-2 a wavelength and of ~300NanoZnO-3 nm, which show is thehigher most protection. harmfulto the skin.

100

60 Untreated NanoZnO-1 NanoZnO-2 40 NanoZnO-3

Transmittance(%) 20

0 200 300 400 500 600 700 Wave length (nm) (a) (b)

Figure 4. UV transmittance curve of (a) untreated fabric and different ZnO nano-coated fabric; (b) untreated fabric, only binder-treated (S-B) fabric, andand binderbinder withwith emulsiﬁer-treatedemulsifier-treated fabricfabric (S-B@E).(S-B@E).

TableOn 1. Average the other UV hand, transmittance the sample (%) of NanoZnO-1, different wavelengths which contains with UPF 1% range. ZnO nanoparticles, Transmittanceexhibits (%) roughly 35% UV transmittance in that region. This indicates that the ZnO nanoparticle enables the fabric toMeasured block 65% UPF of with UV rays.Respect The to coated Average fabric Trans- NanoZnO-2UV Protection shows Cate- nearly Sample UV-A UV-B UV-C mittance% gory * (320–400) nm (280–320) nm (200–280) nm Untreated 70 60 52 5 ± 2 Poor NanoZnO-1 42 35 34 8 ± 3 Moderate NanoZnO-2 7 6 8 28 ± 4 Very good NanoZnO-3 6 5 10 30 ± 3 Very good * Category of UV protection assessed as per AS/NZS 4399: 1996 [57].

Polymers 2021, 13, 2701 7 of 16

~6% transmittance of the UV spectrum. Hence, it blocks 94% of incident light on the UV-B region. The transmittance nature on UV-A of 200–280 nm is similar, as it blocks ~92% of incident light. Therefore, the binder fixes more ZnO nanoparticles on cotton fabric, which brings a higher UV blockage. Eventually, the UV protection ability of treated fabric with the third recipe indicates the highest UV blockage at 280–320 nm. NanoZno-3 provides protection of around 95% UV, as it transmits only ~5% UV rays. This transmittance is similar to the UPF range 25+ designated to the very good UV protection category [52,53]. According to the literature [41], 30+ UPF refers to very good UV protection with 6% UV transmission. However, our treated fabric NanoZnO-3 provides approximately 30 ± 3 (average UPF ranges), indicating that we discovered outstanding UV protection. When all of the data in Table1 are compared, it is clear that the ZnO nano-coating can increase the UV protection of cotton fabric. Significant improvements have been made by using a binder as a fixing agent for the deposition of nanoparticles. In addition, ZnO has a well-defined sun protection power [45,54] and is capable of reflecting both UV-A (320–400 nm) and UV-B (280–320 nm) wavelengths of sunlight [55]. As a result, the coated fabric in this study, which is made up of nano ZnO particles measuring 70 nm (about), exhibits strong resistance to UV light blocking. However, our findings are consistent with the previous investigation of nano ZnO on fabric. Yuwanda and Punnama [56] used poly 4-styrenesulfonic acid to immobilize ZnO nanoparticles on cotton fabrics and obtained similar UV protection. Likewise, AS/NZS 4399 defined three levels of protection: excellent, very good, and good [57], which are also listed in Table1 for our working samples. Finally, it should be noted that our result of significantly improved UV protection of cotton fabric is the attribute of the shielding effect of ZnO nanoparticles [56]. However, the two auxiliary chemical binders and wax emulsion used in this study have a minor impact on UV protection, as it is found from Figure4b that the samples with the binder (S-B) only and the binder with an emulsifier (S-B@E) demonstrate minimal changes in UV transmittance (T%) than that of the untreated fabric. The binder only increases the nano deposition; therefore, the samples NanoZnO-2 and NanoZnO-3 show higher protection.

Table 1. Average UV transmittance (%) of different wavelengths with UPF range.

Transmittance (%) Measured UPF with Respect to UV Protection Sample UV-A UV-B UV-C Average Transmittance% Category * (320–400) nm (280–320) nm (200–280) nm Untreated 70 60 52 5 ± 2 Poor NanoZnO-1 42 35 34 8 ± 3 Moderate NanoZnO-2 7 6 8 28 ± 4 Very good NanoZnO-3 6 5 10 30 ± 3 Very good * Category of UV protection assessed as per AS/NZS 4399: 1996 [57].

3.2. Assessment of Antimicrobial Activity The killing of two bacteria for the action of nano ZnO-coated fabric by three different recipes is presented as the percentage of bacterial reduction (R%). The obtained results of R% are shown in Table2. The agar plate, having a bacterial reduction image of all treated and untreated fabrics, is shown in Figures5 and6. The results show that all three coated fabrics give a notable amount of bacterial reduction. The coated sample NanoZnO-1 achieves 58.76% reduction for S. aureus and 50.54% for E. coli after 1 h of contact time. The sample NanoZnO-2 reduces the highest amount of bacteria with 90.43% reduction for S. aureus and 86.14% for E.coli. The third sample, NanoZnO-3, also shows a bacterial reduction of 84.47% for S. aureus and 80.2% for E.coli in unwashed conditions after 1 h of contact killing. The reduction increases significantly after 24 h of the contact period. The treated fabric NanoZnO-2 and NonoZnO-3 show ~99% reduction in both bacteria after 24 h. Polymers 2021, 13, 2701 8 of 16

Figures 8 and 9 show the higher amount of nano zinc particles in sample NonoZnO-2. Therefore, the increasing amount of nanoparticles causes the higher antibacterial activity of Polymers 2021, 13, x FOR PEER REVIEWthe second sample of NanoZnO-2. Anita et al. [33] found 99% reduction (R%) for S.8 of aureus 16

and 80% for E. coli for the ZnO (2%) nano-treated cotton fabric. Due to the use of a binder in our study, we achieve ~99% bacterial reduction for both S. aureus and E.coli bacteria, even when using 1% nano ZnO. The contribution of the binder on antimicrobial activity is achieves 58.76% reduction for S. aureus and 50.54% for E. coli after 1 h of contact time. The also proved by our previous work [31]. El-Nahhal et al. [58] found around 90–93% bacterial sample NanoZnO-2 reduces the highest amount of bacteria with 90.43% reduction for S. reduction on cotton fabric for ZnO nanoparticles and identiﬁed low wash durability of aureus and 86.14% for E.coli. The third sample, NanoZnO-3, also shows a bacterial reduc- antimicrobial activity. Compared with the results of other related studies, our results of tion of 84.47% for S. aureus and 80.2% for E.coli in unwashed conditions after 1 h of contact bacterial reduction are up to the required standard. killing. The reduction increases significantly after 24 h of the contact period. The treated fabric NanoZnO-2 and NonoZnO-3 show ⁓99% reduction in both bacteria after 24 h. Table 2. Bacterial reduction on untreated and nano-treated fabric for S. aureus and E.coli. Figures 8 and 9 show the higher amount of nano zinc particles in sample NonoZnO- 2. Therefore, the increasingBacterial amount Reduction of nanoparticles R% after 1 h causesBacterial the higher Reduction antibacterial R% after activ- the ity of theSample second sample of NanoZnO-2.Contact Time Anita et al. [33] found 99%24 hreduction Contact Time (R%) for S. aureus and 80% for E. coliS. for aureus the ZnO (2%) nano-treated E. coli cotton S. aureus fabric. Due to the E. use coli of a ⁓ binder Untreatedin our study, we achieve – 99% bacterial – reduction for both – S. aureus and E.coli – bacteria, even when using 1% nano ZnO. The contribution of the binder on antimicrobial NanoZnO-1 activity is also proved by our previous work [31]. El-Nahhal et al. [58] found around 90– 93% bacterialUnwashed reduction on 58.76 cotton fabric for 50.54ZnO nanoparticles 68.30 and identified low 57.11 wash durability5 wash of antimicrobial 40.22activity. Compared 30.11 with the results 52.40 of other related 40.40 studies, our results10 wash of bacterial reduction 25.46 are up to the 18.23 required standard. 31.14 23.6 Nevertheless, due to the use of a binder, our wash stability is higher, as shown in NanoZnO-2 Table 2. Furthermore, the literature supports that the acrylic binder fixes more nanoparticles, resultingUnwashed in intensive 90.43antibacterial action 86.14 [59]. However, 99.50from the second and 97.10 third treated samples,5 wash it can be found 86.24 that the bind 83.60er has a significant 98.16 contribution to 96.01the deposition of10 ZnO wash nanoparticles 85.46 on the surface of 83.00 the textile fabric. 96.20 Eventually, these 93.34 samples develop outstanding properties of antimicrobial activity. The efficient antimicrobial activ- NanoZnO-3 ity of ZnO nanoparticles is explained as the generation of reactive surface oxygen, which kills theUnwashed bacteria by damaging 84.47 the cell membra 80.20ne of microbes [60]. 98.12 Therefore, utilizing 97.45 the present technique5 wash for the deposition 81.53 of sufficient 77.61 ZnO nanoparticles 96.15 is an interesting 95.01 way to participate10 wash in the excellent 82.10 antimicrobial activity 76.48. 94.4 92.34

Figure 5. Bacterial reduction disk images of 1 h contact time for (a) untreated fabric, (b) NanoZnO-1, Figure 5. Bacterial reduction disk images of 1 h contact time for (a) untreated fabric, (b) NanoZnO- (c) NanoZnO-2, and (d) NanoZnO-3 for S. aureus;(e) untreated fabric, (f) NanoZnO-1, (g) NanoZnO-2, 1, (c) NanoZnO-2, and (d) NanoZnO-3 for S. aureus; (e) untreated fabric, (f) NanoZnO-1, (g) h E.coli NanoZnO-2,and ( ) NanoZnO-3 and (h) NanoZnO-3 for . for E.coli.

Table 2. Bacterial reduction on untreated and nano-treated fabric for S. aureus and E.coli.

Bacterial Reduction R% after 1 Hour Contact Time Bacterial Reduction R% after the 24 Hours Contact Time Sample S. aureus E. coli S. aureus E. coli Untreated ------NanoZnO-1 Unwashed 58.76 50.54 68.30 57.11 5 wash 40.22 30.11 52.40 40.40 10 wash 25.46 18.23 31.14 23.6 NanoZnO-2

Polymers 2021, 13, x FOR PEER REVIEW 9 of 16

Unwashed 90.43 86.14 99.50 97.10 5 wash 86.24 83.60 98.16 96.01 10 wash 85.46 83.00 96.20 93.34 NanoZnO-3 Unwashed 84.47 80.20 98.12 97.45 Polymers5 wash2021 , 13, 2701 81.53 77.61 96.15 95.01 9 of 16 10 wash 82.10 76.48 94.4 92.34

FigureFigure 6. 6. BacterialBacterial reduction reduction disk disk images images after after 24 24 h h contact contact time time for for ( (aa)) untreated untreated fabric, fabric, ( (bb)) NanoZnO-1, NanoZnO-1, ( (cc)) NanoZnO-2, NanoZnO-2, andand ( (dd)) NanoZnO-3 NanoZnO-3 for for S.S. aureus aureus andand ( (ee)) untreated untreated fabric, fabric, ( (ff)) NanoZnO-1, NanoZnO-1, ( (g)) NanoZnO-2, NanoZnO-2, and ( h) NanoZnO-3 for E.coli.E.coli.

3.3. EffectNevertheless, of ZnO Nanoparticles due to the on use Crease of a Resistance binder, our wash stability is higher, as shown in TableThe2. Furthermore, recovery angle the of literature the different supports samples that themeasured acrylic binderin degrees fixes is more shown nanoparticles, in Figure 7,resulting showing in that intensive the ZnO antibacterial nanoparticle action has [some59]. However, appreciable from effect thes second on the and crease third recovery treated anglesamples, of cotton it can befabric. found The that untreated the binder fabric has a significanthas 105° (degree) contribution of recovery to the deposition angle and of NanoZnO-1ZnO nanoparticles has 108°. on Hence, the surface the first of thecoating textile with fabric. 1% ZnO Eventually, nanoparticle these samplesshows a develop3% im- provementoutstanding in propertiesrecovery after of antimicrobial creasing. The activity.second sample, The efficient NanoZnO-2, antimicrobial shows a activity 5.7% im- of provementZnO nanoparticles in crease isrecovery. explained Finally, as the the generation highest amount of reactive of crease surface recovery oxygen, is which obtained kills the bacteria by damaging the cell membrane of microbes [60]. Therefore, utilizing the by NanoZnO-3, which delivers around 10% improvement in crease recovery compared withpresent that technique of the untreated for the depositionfabric. Thus, of crease sufficient recovery ZnO nanoparticlesand the easy-care is an property interesting can way be to participate in the excellent antimicrobial activity. improved by the nano ZnO coating and the binder and emulsion. It is known that cotton fabric3.3. Effect is inelastic of ZnO and Nanoparticles contains onso Creasemany Resistancefree hydroxyl (-OH) groups in its structure that are responsible for easy crease formation [61,62]. For the coated fabric of this research, The recovery angle of the different samples measured in degrees is shown in Figure7, ZnO nanoparticles easily penetrate the fabric pores. They are affixed tightly on the surface showing that the ZnO nanoparticle has some appreciable effects on the crease recovery by the binder, and, consequently, it is not easily wrinkled or creased after treatment. More- angle of cotton fabric. The untreated fabric has 105◦ (degree) of recovery angle and over, the emulsion penetrates the cellulose polymer, blocks the free hydroxyl group, and NanoZnO-1 has 108◦. Hence, the first coating with 1% ZnO nanoparticle shows a 3% improves fiber mobility. Thus, the nano ZnO-treated fabric shows better performance improvement in recovery after creasing. The second sample, NanoZnO-2, shows a 5.7% than the untreated fabric, NanoZnO-2 performs much better, and NanoZnO-3 performs improvement in crease recovery. Finally, the highest amount of crease recovery is obtained the best on crease recovery among the samples. by NanoZnO-3, which delivers around 10% improvement in crease recovery compared with that of the untreated fabric. Thus, crease recovery and the easy-care property can be improved by the nano ZnO coating and the binder and emulsion. It is known that cotton fabric is inelastic and contains so many free hydroxyl (-OH) groups in its structure that are responsible for easy crease formation [61,62]. For the coated fabric of this research, ZnO nanoparticles easily penetrate the fabric pores. They are affixed tightly on the surface by the binder, and, consequently, it is not easily wrinkled or creased after treatment. Moreover, the emulsion penetrates the cellulose polymer, blocks the free hydroxyl group, and improves fiber mobility. Thus, the nano ZnO-treated fabric shows better performance than the untreated fabric, NanoZnO-2 performs much better, and NanoZnO-3 performs the best on crease recovery among the samples.

Polymers 2021, 13, 2701 10 of 16 Polymers 2021, 13, x FOR PEER REVIEW 10 of 16

FigureFigure 7.7.Crease Crease recoveryrecovery ofof untreateduntreated and and ZnO ZnO nano-treated nano-treated fabric. fabric.

3.4.3.4. EvaluationEvaluation ofof MechanicalMechanical PropertiesProperties TheThe obtainedobtained resultsresults ofof tensiletensile strength,strength, elongation,elongation, tearingtearing strength,strength, bendingbending length,length, andand friction friction coefficient coefficient are are shown shown in in Table Table3. From3. From the the table, table, it is it found is found that that the twothe samplestwo sam- NanoZnO-1ples NanoZnO-1 andNanoZnO-2 and NanoZnO-2 show show a significant a significant reduction reduction in tensile in tensile strength strength compared com- withpared that with of thethat untreated of the untreated fabric. The fabric. reduction The inreduction tensile strength in tensile is more strength for NanoZnO-2, is more for whereNanoZnO-2, the binder where is used the binder as a fixing is used agent. as a It fix caning be agent. observed It can that be NanoZnO-1observed that treated NanoZnO- with only1 treated ZnO nanoparticleswith only ZnO reduces nanoparticles ~5.6% strength reduces in ⁓ the5.6% warp strength direction in the and warp ~3.9% direction in the weft and direction.⁓3.9% in the The weft use direction. of the binder The increasesuse of the ZnO binder deposition, increases decreasing ZnO deposition, ~10.5% decreasing of tensile strength⁓10.5% of in tensile the warp strength direction in the and warp ~12.23% direction in the and weft ⁓12.23% direction. in the weft direction. On the other hand, for the sample of NanoZnO-3, the tensile strength rises to Table 3. Different mechanical⁓795.20N properties compared of untreated to ⁓730.52N and nano of ZnO-treated the untreated cotton fabric with in the mean warp deviation. direction and Tensile Strength⁓616.32N compared to ⁓572.6N of the Tearinguntreated fabric in the weft direction, which are Elongation (%) Bending Frictional Coefficient Sample Breaking8.8% Force (N)and 7.6% higher in the warp andStrength weft directions, (N) respectively, than that of the un- Length (cm) Warptreated Weft fabric. WarpIn contrast, Weft Anita et Warpal. [33] and Weft Yadav et al. [4] reported Static that nano Kinetic ZnO Untreated 730.52 ± 9deposition 572.60 ± 6 reduced 21.10 ± 3the 14.75tensile± 3 strength 9.11 ± of2 the 4.3 cotton± 1 fabric, 1.8 where± 1 the authors 0.35 did 0.32not use NanoZnO-1 689.3 ± 8any 550.20 other± 5 auxiliaries 20.2 ± 4 for 15.10 the ±deposition2 8.30 ± of3 nano 3.6 ±ZnO.1 Herein, 1.9 ± polyethylene1 0.31 wax emulsion 0.28 ± ± ± ± ± ± ± NanoZnO-2 654.15 7is 502.54used along5 18.5with a3 binder 13.22 and3 1% 6.23 ZnO3 nano 3.1particle.2 Therefore, 2.1 1 the emulsion 0.30 has 0.27 a sig- NanoZnO-3 795.20 ± 9 616.32 ± 7 22.5 ± 5 18.63 ± 4 12.45 ± 4 8.6 ± 4 1.4 ± 1 0.23 0.20 nificant effect on the polymeric bonding of fiber molecules and improves the tensile strength. However, from the analysis of the tensile strength test of the four samples, it is observedOn the that other the hand, ZnO fornanoparticles the sample ofdeposited NanoZnO-3, on the the cotton tensile strengthfabric decrease rises to ~795.20the tensile N comparedstrength in to both ~730.52 warp N and of theweft untreated directions. fabric The inhigher the warp deposition direction of the and ZnO ~616.32 nanoparticle N com- paredcauses to more ~572.6 reduction N of the in untreated tensile strength fabric in as the per weft the direction,results of whichsamples are NanoZnO-1 8.8% and 7.6% and higherNanoZnO-2. in the warpFor resolving and weft the directions, degradation respectively, of tensile than strength, that of one the innovative untreated idea fabric. is the In contrast,use of polyethylene Anita et al. wax [33] andemulsion Yadav during et al. [ 4na] reportedno treatment that similarly nano ZnO to deposition NanoZnO-3, reduced which the tensile strength of the cotton fabric, where the authors did not use any other auxiliaries can be attributed to an 8.8% increase in tensile strength in the warp direction and 7.6% in for the deposition of nano ZnO. Herein, polyethylene wax emulsion is used along with the weft direction compared to that of the untreated fabric as shown in Table 3. Similar a binder and 1% ZnO nanoparticle. Therefore, the emulsion has a significant effect on trends of tensile strength can be found for elongation and tearing strength, as shown in the polymeric bonding of fiber molecules and improves the tensile strength. However, Table 3. The nano ZnO coating without emulsion reduces these two properties for samples from the analysis of the tensile strength test of the four samples, it is observed that the ZnO NanoZnO-1 and NanoZnO-2. Quantitatively, NanoZnO-1 has a reduction of 4.3%, and nanoparticles deposited on the cotton fabric decrease the tensile strength in both warp and NanoZnO-2 has a decrease of 12.3% in elongation along the warp direction compared than weft directions. The higher deposition of the ZnO nanoparticle causes more reduction in that of the untreated fabric. The tearing strength is also reduced in both warp and weft tensile strength as per the results of samples NanoZnO-1 and NanoZnO-2. For resolving directions for samples NanoZnO-1 and NanoZnO-2. On the other hand, the sample the degradation of tensile strength, one innovative idea is the use of polyethylene wax NanoZnO-3 improves the elongation and tearing strength in both warp and weft direc- emulsion during nano treatment similarly to NanoZnO-3, which can be attributed to an tions, which are, no doubt, very noticeable results.

Polymers 2021, 13, 2701 11 of 16

8.8% increase in tensile strength in the warp direction and 7.6% in the weft direction compared to that of the untreated fabric as shown in Table3. Similar trends of tensile strength can be found for elongation and tearing strength, as shown in Table3. The nano ZnO coating without emulsion reduces these two properties for samples NanoZnO-1 and NanoZnO-2. Quantitatively, NanoZnO-1 has a reduction of 4.3%, and NanoZnO-2 has a decrease of 12.3% in elongation along the warp direction compared than that of the untreated fabric. The tearing strength is also reduced in both warp and weft directions for samples NanoZnO-1 and NanoZnO-2. On the other hand, the sample NanoZnO-3 improves the elongation and tearing strength in both warp and weft directions, which are, no doubt, very noticeable results. For textile fabric, bending length is a measure of stiffness, i.e., if the bending length is higher, the fabric stiffness is higher. Therefore, the nano ZnO treatment slightly increases the stiffness of the cotton fabric, as can be observed in Table3. Again, the nano deposition with the binder makes the fabric stiffer, as NanoZnO-2 achieves a bending length of 2.1 cm, and that is 16% higher than that of the untreated fabric. However, the sample NanoZnO-3 shows a 22.2% reduction in bending length than that of the untreated fabric due to its softness, smoothness, and mobility imparted by the polyethylene wax emulsion. Therefore, increasing the bending length for the first and second nano-treated samples might marginally make the fabric stiffer, thereby reducing fabric mobility. Consequently, the force imparted could not be readily distributed across the whole fabric, which might be the reason for the reduction in tensile strength. The reduction in tensile strength was also confirmed by the literature [63] through the overall chemical finishing of the textile fabric. From the results of frictional resistance in Table3, the ZnO nanoparticle decreases the frictional co-efficient of all the nano-treated samples compared with the untreated fabric. An excellent feature is obtained for the sample NanoZnO-3, where the use of emulsion reduces both static and kinetic frictional resistance remarkably. This type of nano-coating will help textile fabric resist mechanical damage during the wet process and garment preparation. Most importantly, due to the reduction in kinetic friction, the cutting speed can be increased, and the low static friction improves the sewing production rate.

3.5. Analysis of Surface Morphology The morphological change in the untreated and nano ZnO-treated fabric is observed by SEM, as shown in Figure8a–f, to support the analyses of the results obtained by the present investigation. The samples are enlarged with ×3000 magnification for the betterment of observation. The untreated fabric shows a smooth and clear image of the cotton fiber structure in Figure8a, whereas the treated fabric shows a sufficient amount of nanoparticles on the fabric surface in Figure8b–d. Additionally, Figure8e; Figure8f represents the SEM images of NanoZnO-2 and NanoZnO-3 after five washes, followed by the standard test method [64]. The image shows a sufficient amount of ZnO nanoparticles on the surface of the washed fabric that happens due to a binder. The binder improves bonding and imparts longevity of nano deposition. The EDS (energy dispersive spectroscopy) images are depicted in Figure9a–d. Both SEM and EDS analyses indicate that the nano-treated sample with only nano ZnO contains fewer nanoparticles than the other treated fabrics. The SEM analysis supports all of the obtained results, i.e., the higher concentration of nano ZnO causes an improvement in functional activity but degrades mechanical properties. However, the use of polyethylene wax emulsion and the binder on the nano ZnO-coated fabrics ensures a sufficient amount of nanoparticle deposition to improve functional and mechanical properties. Polymers 2021, 13, 2701 12 of 16 Polymers 2021, 13, x FOR PEER REVIEW 12 of 16

(a) (b)

(e) (f)

Figure 8. SEMSEM images images of of different different samples: samples: (a) ( auntreated) untreated fabric, fabric, (b) (bNanoZnO-1,) NanoZnO-1, (c) (NanoZnO-2,c) NanoZnO-2, (d) (NanoZnO-3,d) NanoZnO-3, (e) NanoZnO-2(e) NanoZnO-2 after after washing, washing, and and (f) NanoZnO-3 (f) NanoZnO-3 after after washing. washing.

(a) (b)

Figure 9. Cont.

Polymers 2021, 13, 2701 13 of 16

Figure 9. EDS of different samples: (a) untreated fabric, (b) NanoZnO-1, (c) NanoZnO-2, and (d) NanoZnO-3.

4. Conclusions Cotton fabric is coated by synthesized ZnO nanoparticles following the mechanical thermo-fixation method. Three different coating recipes are used with the aim of improving the mechanical properties as well as functional qualities. The nano deposition on the fabric surface is proved by the SEM and EDS images. Though the ZnO nanoparticle is used to develop antimicrobial activity in making medical cloth, the degradation of mechanical properties is the drawback of nano ZnO treatment. For the improvement of those mechanical properties, polyethylene wax emulsion is added with nano ZnO. It is an agent that forms a flexible film on the fabric surface, makes the fabric soft with a smooth coating, and improves mechanical properties. Excellent and encouraging results can be found for the antibacterial activity, where the nano treatment with the binder shows an improvement of ~99% bacterial reduction for S. aureus and ~97% for E.coli after 24 h. The nano ZnO with the binder and emulsion shows ~98% bacterial reduction for S. aureus and ~97% for E.coli with outstanding wash durability. The UV protection is also excellent for nano ZnO with the binder and nano ZnO with the binder and emulsion, restricting approximately 90% of UV rays of the 250–375 nm wavelength region. It is found that the use of the binder for the coating of nano ZnO degrades tensile strength, elongation, tearing strength, and the frictional coefficient. In contrast, excellent improvement of these properties is found when polyethylene wax emulsion and the binder are used to coat nano ZnO. Thus, this study demonstrates the improvement of the functional properties of cotton fabric as well as the mechanical properties. It promotes longevity, serviceability, comfortability, and high-quality finished cotton fabric. Moreover, the UV protective textile produced by coating with nano ZnO, binder, and emulsion becomes an essential, valuable item as curtains, awnings, and summer clothes along with its application in the medical sector.

Author Contributions: Conceptualization, I.S.T. and M.A.; methodology, I.S.T.; validation, formal analysis, I.S.T. and M.A.; investigation, I.S.T.; resources, M.A.; writing—original draft preparation, I.S.T.; writing—review and editing, M.A. and I.S.T.; supervision, M.A. All authors have read and agreed to the published version of the manuscript. Funding: Not applicable. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Not applicable. Acknowledgments: The authors like to convey their heartfelt appreciation to the Mechanical Engi- neering Department of BUET for their kind support of this work. We are grateful to the departments of Glass and Ceramics Engineering and Biomedical Engineering of BUET to assist the characterization analyses and antimicrobial testing. Polymers 2021, 13, 2701 14 of 16

Conﬂicts of Interest: The authors declare that they have no conﬂicts of interest.

Abbreviations

SEM Scanning Electron Microscope EDS Energy Dispersive Spectroscopy XRD X-Ray Dispersive Spectroscopy UPF Ultraviolet Protection Factor UV Ultraviolet Ray T% Transmission Percentage AATCC The American Association of Textile Chemists and Colorists

References 1. Yetisen, A.K.; Qu, H.; Manbachi, A.; Butt, H.; Dokmeci, M.R.; Hinestroza, J.P.; Skorobogatiy, M.; Khademhosseini, A.; Yun, S.H. Nanotechnology in Textiles. ACS Nano 2016, 10, 3042–3068. [CrossRef][PubMed] 2. Kathirvelu, S.; D’Souza, L.; Dhurai, B. Nanotechnology applications in textiles. Indian J. Sci. Technol. 2008, 1.[CrossRef] 3. Robles-García, M.A.; Rodriguez-Felix, F.; Marquez-Rios, E.; Aguilar, J.A.; Barrera-Rodriguez, A.; Aguilar, J.; Ruiz-Cruz, S.; Del-Toro-Sánchez, C.L. Applications of nanotechnology in the agriculture, food, and pharmaceuticals. J. Nanosci. Nanotechnol. 2016, 16, 8188–8207. [CrossRef] 4. Yadav, A.; Prasad, V.; Kathe, A.A.; Raj, S.; Yadav, D.; Sundaramoorthy, C.; Vigneshwaran, N. Functional Finishing in Cotton Fabrics Using Zinc Oxide Nanoparticles. Bull. Mater. Sci. 2006, 29, 641–645. [CrossRef] 5. Selvam, S.; Rajiv Gandhi, R.; Suresh, J.; Gowri, S.; Ravikumar, S.; Sundrarajan, M. Antibacterial effect of novel synthesized sulfated β-cyclodextrin crosslinked cotton fabric and its improved antibacterial activities with ZnO, TiO2 and Ag nanoparticles coating. Int. J. Pharm. 2012, 434, 366–374. [CrossRef][PubMed] 6. Simoncic, B.; Tomsic, B. Structures of Novel Antimicrobial Agents for Textiles—A Review. Text. Res. J. 2010, 80, 1721–1737. [CrossRef] 7. Saleem, H.; Zaidi, S.J. Sustainable Use of Nanomaterials in Textiles and Their Environmental Impact. Materials 2020, 13, 5134. [CrossRef] 8. Dastjerdi, R.; Montazer, M. A review on the application of inorganic nano-structured materials in the modification of textiles: Focus on anti-microbial properties. Colloids Surfaces B Biointerfaces 2010.[CrossRef] 9. Tania, I.S.; Ali, M.; Islam, Z. Solaiman Development of antimicrobial activity and mechanical performances of cotton fabric treated with silver nano particles (AgNPs). AIP Conf. Proc. 2019, 2121, 15003. [CrossRef] 10. Pan, Z.W.; Wang, Z.L. Nanobelts of semiconducting oxides. Science 2001, 291, 1947–1949. [CrossRef][PubMed] 11. Tania, I.S.; Ali, M.; Azam, M.S. Mussel-Inspired Deposition of Ag Nanoparticles on Dopamine-Modified Cotton Fabric and Analysis of its Functional, Mechanical and Dyeing Properties. J. Inorg. Organomet. Polym. Mater. 2021, 1–12. [CrossRef] 12. Zahran, M.K.; Ahmed, H.B.; El-Rafie, M.H. Surface modification of cotton fabrics for antibacterial application by coating with AgNPs-alginate composite. Carbohydr. Polym. 2014.[CrossRef][PubMed] 13. Tania, I.S.; Ali, M.; Azam, M.S. In-situ synthesis and characterization of silver nanoparticle decorated cotton knitted fabric for antibacterial activity and improved dyeing performance. SN Appl. Sci. 2019, 1, 64. [CrossRef] 14. Galkina, O.L.; Vinogradov, V.V.; Vinogradov, A.V.; Agafonov, A.V. Development of the low-temperature sol-gel synthesis of TiO2 to provide self-cleaning effect on the textile materials. Nanotechnol. Russ. 2012, 7, 406–414. [CrossRef] 15. Kale, B.M.; Wiener, J.; Militky, J.; Rwawiire, S.; Mishra, R.; Jacob, K.I.; Wang, Y. Coating of cellulose-TiO2 nanoparticles on cotton fabric for durable photocatalytic self-cleaning and stiffness. Carbohydr. Polym. 2016.[CrossRef] 16. Montazer, M.; Pakdel, E. Self-cleaning and color reduction in wool fabric by nano titanium dioxide. J. Text. Inst. 2011.[CrossRef] 17. Isaifan, R.J.; Samara, A.; Suwaileh, W.; Johnson, D.; Yiming, W.; Abdallah, A.A.; Aïssa, B. Improved Self-cleaning Properties of an Efficient and Easy to Scale up TiO2 Thin Films Prepared by Adsorptive Self-Assembly. Sci. Rep. 2017.[CrossRef] 18. Sivakumar, A.; Murugan, R.; Sundaresan, K.; Periyasamy, S. UV protection and self-cleaning finish for cotton fabric using metal oxide nanoparticles. Indian J. Fibre Text. Res. 2013, 38, 285–292. 19. Chinta, S.K.; Landage, S.M.; Swapnal, J. Water Repellency of Textiles Through Nanotechnology. Int. J. Adv. Res. IT Eng. 2013, 2, 36–57. 20. Dodd, A.C.; McKinley, A.J.; Saunders, M.; Tsuzuki, T. Effect of particle size on the photocatalytic activity of nanoparticulate zinc oxide. J. Nanopart. Res. 2006.[CrossRef] 21. Khan, M.Z.; Baheti, V.; Ashraf, M.; Hussain, T.; Ali, A.; Javid, A.; Rehman, A. Development of UV Protective, Superhydrophobic and Antibacterial Textiles Using ZnO and TiO2 Nanoparticles. Fibers Polym. 2018.[CrossRef] 22. Arnold, M.S.; Avouris, P.; Pan, Z.W.; Wang, Z.L. Field-effect transistors based on single semiconducting oxide nanobelts. J. Phys. Chem. B 2003.[CrossRef] 23. Jiang, J.; Pi, J.; Cai, J. The Advancing of Zinc Oxide Nanoparticles for Biomedical Applications. Bioinorg. Chem. Appl. 2018, 2018, 1062562. [CrossRef][PubMed] Polymers 2021, 13, 2701 15 of 16

24. Nguyen, K.T.; Mai, D.X.N.; Doan, U.T.T.; Nguyen, T.T.; Dang, Y.T.; Ta, H.K.T.; Phan, T.B.; Pham, N.K. The chitosan/ZnO bio-nanocomposites with selective antibacterial efficiency. J. Mater. Res. 2021, 36, 508–517. [CrossRef] 25. Hussain, S.G.; Liu, D.; Huang, X.; Sulieman, K.M.; Liu, J.; Wang, T. Morphological and optical properties of ZnO nanoparticles and porous microspheres. In Proceedings of the Technology & Innovation Sustainable Development Conference, Khon Kaen, Thailand, 25–26 January 2006. 26. Jiménez-Rosado, M.; Perez-Puyana, V.; Sánchez-Cid, P.; Guerrero, A.; Romero, A. Incorporation of ZnO nanoparticles into soy protein-based bioplastics to improve their functional properties. Polymers 2021, 13, 486. [CrossRef] 27. Majumdar, A.; Singh Butola, B.; Awasthi, N.; Chauhan, I.; Hatua, P. Improving the mechanical properties of p-aramid fabrics and composites by developing ZnO nanostructures. Polym. Compos. 2018, 39, 3300–3306. [CrossRef] 28. Pintarić,L.M.; Škoc, M.S.; Bilić,V.L.; Pokrovac, I.; Kosalec, I.; Rezić,I. Synthesis, Modification and Characterization of Antimicro- bial Textile Surface Containing ZnO Nanoparticles. Polymers 2020, 12, 1210. [CrossRef][PubMed] 29. Li, Y.; Zou, Y.; Hou, Y. Fabrication and UV-blocking property of nano-ZnO assembled cotton fibers via a two-step hydrothermal method. Cellulose 2011.[CrossRef] 30. Ugur,ˇ ¸S.S.;Sarii¸sik,M.; Akta¸s,A.H.; Uçar, M.Ç.; Erden, E. Modifying of cotton fabric surface with Nano-ZnO multilayer films by Layer-by-Layer deposition method. Nanoscale Res. Lett. 2010, 5, 1204. [CrossRef][PubMed] 31. Tania, I.S.; Ali, M. Effect of the coating of zinc oxide (ZnO) nanoparticles with binder on the functional and mechanical properties of cotton fabric. Mater. Today Proc. 2021, 38, 2607–2611. [CrossRef] 32. Arputharaj, A.; Nadanathangam, V.; Shukla, S.R. A simple and efficient protocol to develop durable multifunctional property to cellulosic materials using in situ generated nano-ZnO. Cellulose 2017, 24, 3399–3410. [CrossRef] 33. Subash, A.A.; Chandramouli, K.V.; Ramachandran, T.; Rajendran, R.; Muthusamy, M. Preparation, characterization, and functional analysis of zinc oxide nanoparticle-coated cotton fabric for antibacterial efficacy. J. Text. Inst. 2012.[CrossRef] 34. Vigneshwaran, N.; Kumar, S.; Kathe, A.A.; Varadarajan, P.V.; Prasad, V. Functional finishing of cotton fabrics using zinc oxide-soluble starch nanocomposites. Nanotechnology 2006.[CrossRef] 35. Elmaaty, T.; Mandour, B. ZnO and TiO2 Nanoparticles as Textile Protecting Agents against UV Radiation: A Review. Asian J. Chem. Sci. 2018.[CrossRef] 36. Jatoi, A.W.; Khatri, Z.; Ahmed, F.; Memon, M.H. Effect of Silicone Nano, Nano/Micro and Nano/Macro-Emulsion softeners on color yield and physical characteristics of dyed cotton fabric. J. Surfactants Deterg. 2015, 18, 205–211. [CrossRef] 37. Ezazshahabi, N.; Tehran, M.A.; Latifi, M. Predictive model for the frictional characteristics of woven fabrics optimized by the genetic algorithm. J. Text. Inst. 2018, 109, 1083–1090. [CrossRef] 38. Heywood, D. Textile Finishing, Society of Dyers and Colourists, UK, 2003. Thompson Text. Res. J. 1996, 66, 329. 39. JinlubEco NP-825N. Technical Information, Polyethyl. Wax Emuls. Smoothness Softener. (n.d.) 1–3. Available online: http: //www.jintex.com.tw (accessed on 1 March 2016). 40. Kawano, T.; Imai, H. A simple preparation technique for shape-controlled zinc oxide nanoparticles: Formation of narrow size-distributed nanorods using seeds in aqueous solutions. Colloids Surfaces A Physicochem. Eng. Asp. 2008.[CrossRef] 41. Standard JCPDS Pattern for ZnO, Alphabetical Index; Inorg. Compd. Int. Cent. Diffr. Data, Newt: Kennett Square, PA, USA, 1977. 42. Singh, N.; Mehra, R.M.; Kapoor, A. Synthesis and characterization of ZnO nanoparticles. J. Nano Electron. Phys. 2011.[CrossRef] 43. Tania, I.S.; Ali, M.; Arafat, M.T. 6-Processing techniques of antimicrobial textiles. In Antimicrobial Textiles from Natural Resources; Woodhead Publishing: Sawston, UK, 2021; pp. 189–215. ISBN 978-0-12-821485-5. 44. Polefka, T.G.; Meyer, T.A.; Agin, P.P.; Bianchini, R.J. Effects of Solar Radiation on the Skin. J. Cosmet. Dermatol. 2012, 11, 134–143. [CrossRef] 45. Tsuzuki, T.; Wang, X. Nanoparticle Coatings for UV Protective Textiles. Res. J. Text. Appar. 2010, 14, 9–20. [CrossRef] 46. Saravanan, D. UV protection textile materials. Autex Res. J. 2007, 7, 53–62. 47. ASTM E2149. 01 Standard Test Method for Determining the Antimicrobial Activity of Immobilized Antimicrobial Agents under Dynamic Contact Conditions. Available online: https://www.astm.org/DATABASE.CART/HISTORICAL/E2149-01.htm (accessed on 25 May 2018). 48. Elshafei, A.; El-Zanfaly, H.T. Application of Antimicrobials in the Development of Textiles. Asian J. Appl. Sci. 2011, 4, 585–595. [CrossRef] 49. Yavari Rameshe, R.; Mousazadegan, F.; Latifi, M. Investigation of worsted woven fabric’s static friction coefficient considering fabric direction. J. Text. Inst. 2020.[CrossRef] 50. AATCC Test Method 66-2008 Wrinkle Recovery of Woven Fabrics: Recovery Angle. AATCC Technical Manual; American Association of Textile Chemists and Colorists: Durham, NC, USA, 2010; pp. 91–94. 51. Bilimis, Z. Measuring the UV Protection Factor (UPF) of Fabrics and Clothing; Varian Australia Pty Ltd.: Victoria, Australia, 1994; Volume 3170, pp. 1–4. 52. Alam, M.M.; Islam, M.T. A Review on Ultraviolet Protection of Textiles. Int. J. Eng. Technol. Sci. Res. 2017, 4, 404–412. 53. Allen, M.; Bain, G. Measuring the UV Protection Factor of Fabric, Retrieved March 25, 2008, from Varian Aust. Pty Ltd. 2008, pp. 1–4. Available online: http//www.thermo.com/eThermo/CMA/PDFs/Articles/articlesFile$\backslash$_6716.pdf (accessed on 1 May 2018). 54. Smijs, T.G.; Pavel, S. Titanium dioxide and zinc oxide nanoparticles in sunscreens: Focus on their safety and effectiveness. Nanotechnol. Sci. Appl. 2011, 4, 95–112. [CrossRef][PubMed] Polymers 2021, 13, 2701 16 of 16

55. Lee-Yae Tan, L.T.S.; Bee, S.-T.; Chantara, T.; Ratnam, K.-K.W.; Tiam-Ting Tee, A.R.R. A review of antimicrobial fabric containing nanostructures metal-based compound. J. Vinyl Addit. Technol. 2019, 25, E3–E27. [CrossRef] 56. Iamphaojeen, Y.; Siriphannon, P. Immobilization of zinc oxide nanoparticles on cotton fabrics using poly 4-styrenesulfonic acid polyelectrolyte. Int. J. Mater. Res. 2012, 103, 643–647. [CrossRef] 57. Australian/New Zealand Standard 4339-1997: Information Technology–Telecommunications and Information Exchange between Systems–Private Integrated Services Network–Inter-Exchange Signalling Protocol–Call Transfer Supplementary Service. Available online: https://www.standards.govt.nz/shop/asnzs-43391997/ (accessed on 15 May 2017). 58. El-Nahhal, I.M.; Elmanama, A.A.; El Ashgar, N.M.; Amara, N.; Selmane, M.; Chehimi, M.M. Stabilization of nano-structured ZnO particles onto the surface of cotton ﬁbers using different surfactants and their antimicrobial activity. Ultrason. Sonochem. 2017, 38, 478–487. [CrossRef] 59. Wang, L.; Hu, C.; Shao, L. The antimicrobial activity of nanoparticles: Present situation and prospects for the future. Int. J. Nanomedicine 2017, 12, 1227–1249. [CrossRef] 60. Padmavathy, N.; Vijayaraghavan, R. Enhanced bioactivity of ZnO nanoparticles—An antimicrobial study. Sci. Technol. Adv. Mater. 2008, 9.[CrossRef][PubMed] 61. Shady, K.E.; Michael, M.N.; Shimaa, H.A. Effects of zinc oxide nanoparticles on the performance characteristics of cotton, polyester and their blends. AIP Conf. Proc. 2012, 1459, 356–359. [CrossRef] 62. Tania, I.S.; Kabir, S.M.; Uddin, M.Z. Effects of Resin Treatments on the Quality of Cotton Fabric Dyed with Reactive Dye. Fibres Text. East. Eur. 2018, 26, 102–107. [CrossRef] 63. Whishaw, I.Q.; Kolb, B. The Behavior of the Laboratory Rat: A Handbook with Tests; Oxford University Press: Oxford, UK, 2004; ISBN 0198036841. 64. AATCC Test Method 61-2009 Colour Fastness to Washing; American Asociation of Textile Chemists and Colorists (AATCC): Research Triangle, NC, USA, 2009.