Facile, Scalable Spray Coating of Stable Emulsion for Transparent

Subscriber access provided by TUFTS UNIV

Article

Facile, Scalable Spray Coating of Stable Emulsion for Transparent Self-cleaning Surface of Cellulose-based Materials Jie Wei, Gang Zhang, Jing Dong, Huatian Wang, Yunlong Guo, Xiao Zhuo, Changgui Li, Hui Liang, Shaohua Gu, Canghai Li, Xiaoying Dong, and Yongfeng Li ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/acssuschemeng.8b00962 • Publication Date (Web): 15 Jul 2018 Downloaded from http://pubs.acs.org on July 16, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Sustainable Chemistry & Engineering

Facile, Scalable Spray Coating of Stable Emulsion for Transparent Self-cleaning Surface of Cellulosebased Materials †

†

‡

†

†

†

Jie Wei ,a, Gang Zhang ,a, Jing Dong ,a, Huatian Wang , Yunlong Guo , Xiao Zhuo , Changgui Li §

, Hui Liang , Shaohua Gu , Canghai Li#, Xiaoying Dong ,*, Yongfeng Li ,*

†

Shandong Provincial University Key Laboratory of Silviculture, Forestry College, Shandong

‡

†

†

†

Agricultural University, No.61 Daizong Road, Taian 271018, China ‡

College of Chemistry and Material Science, Shandong Agricultural University, No.61 Daizong

Road, Taian 271018 China §

Research Institute of Wood Science, Shandong Academy of Forestry, No.42 East Cultural

Road, Jinan 250014, China #

Sihong Inovo Wood Industry Co. Ltd, No.1 Industrial Park of Chengtou Town, Suqian 223900,

China

*

Corresponding Authors: [email protected], [email protected]; [email protected]

KEYWORDS: wood, cellulose, spray coating, transparent, superhydrophobicity, self-cleaning

ACS Paragon Plus Environment

1

ACS Sustainable Chemistry & Engineering 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 42

ABSTRACT: Cellulose-based materials are vulnerable to moisture and microorganisms and thus lose their original mechanical properties and durability; meanwhile, self-cleaning technique as a disruptive nanotechnology of water-proof are attracting tremendous interest. Here, we develop a facile, cheap and scalable ‘top-down’ strategy to fabricate transparent self-cleaning surface for cellulose-based materials by spray-coating stable emulsion of nano-SiO2 particles. The nanoparticles are precisely synthesized in average diameter of ~110nm via a sol-gel way, and

finely

tailored

with

hydrophobic

function

by

successive

modification

of

polydimethylsiloxane (PDMS) and heptadecafluoro-1,1,2,2-tetradecyl trimethoxysilane (17F). The modified nano-SiO2 particles well distributed on microscale roughing surface of the cellulose-based materials by spray coating form a micro-/nano- two tier structure to entrap air for water resistance, and thus build a superhydrophobic surface with static water contact angle (WCA) over 150o and dynamic contact angle less than 10o. The spray-coated superhydrophobic surface maintains the paper handwriting and wood texture, and holds their original mechanical properties when they exposed to wet conditions, indicating a transparent water-proof coating built on the materials. Such coating also exhibits dust proof and anti-bio-adhesive behavior, which, integrated with light transparency and water repellency, positions a transparent selfcleaning surface capable of being applied in various environments where it resisting water, dust, microorganisms and even acid or alkaline, and being potentially applied to a wider range of materials other than cellulose-based materials.


2

Page 3 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


INTRODUCTION Material is basis for progress of science and technology and development of human society. For example, steel, nylon and carbon fiber, as landmark materials in different historical periods, play key roles in the social development1-3. However, these materials are mostly derived from nonrenewable resources, which are becoming rapidly depleted. Therefore, the current society is facing serious challenge of unsustainable development. Moreover, the processing and industrialization of these non-renewable resources often leads to ecological destruction and environmental pollution4. Consequently, ‘green and sustainable development’ has become the theme of our modern society. Using the abundant green, renewable and biodegradable resources instead of non-renewable materials to promote the human social development corresponds to the above concept, which have reached a consensus by our academia and industry5-6. Many researches on the development of advanced materials with natural renewable resources are hence reported. For example, plant fibers are developed to aerogels, nanomaterials; and animal tissues are prepared into hydrogel, 3D printed biomaterials7-8. Among them, cellulose, mainly from terrestrial plants, is the most abundant natural bio-polymer on earth. Its excellent mechanical properties originated from high crystallinity, rich hydroxyl groups, easy availability, biodegradability and renewability make it an ideal candidate to be potentially applied in high-end areas such as energy-environment, biomedicine, electronic information and so on6,9. For instance, the popular nanocellulose with diameter in nanometer scale is regarded as a green advanced material which is comparable to carbon nanotube in terms of the mechanical properties10. Cellulose-based paper and wood which have been utilized as traditional materials for thousands of years, are still indispensable raw materials in our modern society, because of their wide


3


Page 4 of 42

applications in the fields of construction, indoor decoration and information media6. Therefore, the cellulose-based materials have always played an irreplaceable role in the development of human society, and will still play a key role in the scientific and technological progress in future11-13. Their wide and value-added utilization guarantees the green and sustainable development of the current society. However, the sufficient hydroxyl groups of cellulose easily absorb moisture via hydrogen bonds, which leads to shape deformation, strength reduction, sever mould and decay erosion of the cellulose-based materials, and accordingly degrades the materials and reduces their durability6,14-15. For example, the handwriting on paper is blurred and the strength of the paper is drastically decreased when the paper absorbs water16-17. Nanocellulose absorbs moisture leading to destruction of the nanocellulose-based devices18-25. Wood after moisture absorption could occur dimensional swelling, shape warping, strength loss, and even mould and decay attack26-28. Thus, it is crucial to waterproof such materials. Many explorations on improving water resistance of cellulose-based materials have been reported29-30. For example, paints or resins have been applied to coat paper and wood for water resistance; or substituting hydroxyl groups of cellulose with hydrophobic groups to achieve hydrophobic cellulose-based materials31-32. However, these waterproofing methods typically possess obvious disadvantages, e.g., many coatings pollute the environment due to release of the volatile organic compounds (VOCs); and the modification of hydroxyl group is complex and costly, which restricts the up-scaling production33-34. Recently, the emerging technology of superhydrophobic surface, inspired from the non-sticking phenomenon of the lotus leaf, has aroused tremendous interest35. It enables material surface with water contact angles (WCAs) greater than 150° and water sliding angles smaller than 10o, leading to the water droplets easily rolled off the surface when the material is slightly inclined36. Such technology is essentially


4

Page 5 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


different from the previously reported technologies on the principle of waterproof. It bio-mimics the microstructure and composition characteristic of lotus leaf surface by building hierarchical micro-/nano- two-tier structure on materials surface, along with decoration of low energy surface substances, which can entrap air to strongly repellent water37. Consequently, it is considered to be a disruptive innovation technology, that both the surface rough structure and low surface energy composition combiningly contribute permanent waterproof function to materials surface38. As far as it is known, many methods have been explored to prepare superhydrophobic surface. For example, sol-gel method, chemical vapor deposition (CVD) method, electrospinning, template method, hydrothermal method, ATRP method and so on30,39-41. However, these ways are facing serious challenges to industrialization because of light opaque of the coating, high toxicity of raw materials, complex implementation processes, environmental pollution and high cost of the process30,42. Consequently, seeking a simple, environmental-friendly, low-cost, and scalable method is the focus of the current researches, and the features are crucial for the superhydrophobic technology to achieve practical applications. Additionally, the technology on transparency of the superhydrophobic surface is facing challenge in real applications43. As we know, the effects of surface roughness on the superhydrophobicity and transparency of surface coating are contrary, which is mainly due to the fact that increasing the surface roughness can effectively improve the hydrophobicity, while roughing surface could produce higher diffuse reflection to reduce the transparency of the surface coating. Therefore, preparing superhydrophobic coating with high transparency has become the focus of the research areas44-48. Researchers have explored varies methods to prepare transparent superhydrophobic coatings with high transparency, such as deposition, plasma etching, layer-by-layer self-assembly, etc. Deng et al used soot as a soft template to prepare a


5


Page 6 of 42

transparent silica coating with porous network structure by chemical vapor deposition and subsequent high-temperature forging, and then deposited fluorine-containing silane to obtain transparent

superhydrophobic

coating49.

Bhushan

et

al

etched

the

surface

of

polydimethylsiloxane with O2/CF4 mixture gas to obtain suitable roughness, and then deposited perfluorooctane trichlorosilane on polydimethylsiloxane surface to obtain superhydrophobic coating with high transparency50. Bravo et al reported superhydrophobic coating with 90% opacity, which is obtained by depositing nanoscale SiO2 and polystyrene sulfonate iodine on the substrate through layer-by-layer self-assembly technique51. However, all the above methods have the disadvantage of complicated processes, limiting their real industrialization. Under such context, we, here, develop a facile yet easy-operating ‘top-down’ approach to build transparent superhydrophobic surface for cellulose-based materials by synthesizing and spray-coating the stable nano-SiO2 colloidal emulsion. The latex mainly consists of modified nano-SiO2 particles with diameter of ~100nm and ethanol as solvent, which can be stably suspended for more than one year. The stable colloidal emulsion for spray coating, which, along with easy-operating, low-cost, environmental-friendly, scalable synthesis and processing features, light transparency, positions the approach to be a promisingly industrial application way for transparent self-cleaning surface built on cellulose-based materials. RESULTS AND DISCUSSION The stable colloidal emulsion was formed by ethanol as solvent and modified nano-SiO2 as colloidal particles, which were precisely synthesized by tetraethyl orthosilicate (TEOS) and NH3•H2O via a sol-gel way, followed by successive modification with polydimethylsiloxane (PDMS) and heptadecafluoro-1,1,2,2-tetradecyl trimethoxysilane (17F). The synthesizing


6

Page 7 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


process is facile due to only three simple steps underwent: 1) sol-gel reaction with mild stirring under room temperature to derive nano-SiO2, 2) PDMS decoration of the nano-SiO2 with mild stirring under room temperature, and 3) 17F decoration with mild stirring under room temperature. Then, the emulsion was spray-coated on cellulose-based materials to form evenly distributed nanoparticles layer, which rarely affected the light scattering and thus kept the transparency10,25,46-48. As the cellulose-based materials like paper and wood possessing roughing surface in micrometer scale, their native surface overlaid with the nanoparticles layer could build micro-/nano- hierarchical structure which can easily trap air to repel water. Such roughness theoretically provides less contact area for water droplets and dust to stay on surface, which, along with the waterproofing air and hydrophobic surface composition, results in superhydrophobic surface that the water droplets stood in spherical form and self-cleaning surface that the dusts could be easily cleaned away by the fallen water droplets (Figure 1a)30. The facile method could be industrially applied on cellulose-based materials to provide transparent self-cleaning surface for paper, wood and so on (Figure 1b).


7


Page 8 of 42

Figure 1. Schematic illustration to the spray-coating way for cellulose-based materials. (a) Process and mechanism of the spray coating for self-cleaning surface; (b) the self-cleaning behavior of the resulted cellulose-based materials. Figure 2a shows that the synthesized colloidal emulsion presents in light blue color. Based on the Rayleigh scattering theory that the nanosized materials when evenly dispersed in liquid could exhibit light blue color due to light scattering, we can conclude that the synthesized emulsion contains well-distributed nanoscale SiO2 particles52. SEM, TEM and AFM characterizations reveal that the SiO2 particles present in spherical form with diameter of ~100nm (Figure 2b,c,S1). Laser particle size analyzer exhibits that the diameters of the nano-SiO2 particles are mainly distributed in the range of 90nm~150nm with average value of ~110nm (Figure 2d). Our experiment also indicates that the synthesized colloidal emulsion could be stored at room


8

Page 9 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


condition for more than one year without obvious precipitate, indicating a stable emulsion capable of being large-scalely applied by spray coating. XPS and FTIR characterizations indicate that the nano-SiO2 particles were successfully modified by grafting chains containing Si and F elements, which was respectively originated from PDMS and 17F (Figure 2e,f,S2,S3). In the XPS full-scan spectra, the Si content in SiO2 particle is highest, while the Si content in SiO2PDMS is relative lower than that of SiO2 particle because of relative higher C content originated from PDMS; the new F element presented in the SiO2-PDMS-17F proves the effective modification of 17F. In FTIR spectra (Figure S3), the C-F peak almost overlaps the C-Si peak, however, the magnified FTIR spectra presents that the two spectra are not well matched, indicating the existance of F element. When spray-coating the stable colloidal emulsion on smooth glass surface, the static water contact angle reaches 155o, indicating superhydrophobic surface being built on glass. While for the nano-SiO2 just being modified by PDMS or 17F, the resulted colloidal emulsion could only endow the glass with water contact angle of ~143o (Figure 2g). The comparable results prove the effectiveness of the successive treatments on nano-SiO2 particles for superhydrophobic surface.


9


Page 10 of 42

Figure 2. Characterization of the synthesized nano-SiO2 and their surface modification. (a) Digital photo of the stable emulsion and schematic illustration to the synthesized nano-SiO2; (b) SEM image of the nano-SiO2; (c) TEM image of the nano-SiO2; (d) the diameter distribution of the nano-SiO2; (e) XPS full-scan spectra of the pure nano-SiO2 and the modified nano-SiO2 particles; (f) C 1s high-resolution scan spectra of the nano-SiO2 modified by PDMS and 17F; (g) the water contact angles of glass surface after being spray-coated by nano-SiO2 particles with different surface components. When spray-coating the stable emulsion to paper surface, the handwritings on the paper still keep clear without being blurred, indicating that the formed coating is transparent (Movie 1). Similar transparency is presented on nanocellulose paper (Figure S4, Movie 2) and glass (Figure


10

Page 11 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


S5), respectively. The SEM characterization shows that the coating is just one layer of nano-SiO2 particles with ~100nm thickness, and the transmittance of the superhydrophobic nanocellulose paper is almost similar to that of the control nanocellulose paper, reaching almost 90% when wavelength varied from 400nm to 800nm (Figure S4). Consequently, we conclude that the monodisperse of nano-SiO2 particles is the key of transparency of the self-cleaning coating. The water droplets on the paper present spherical form with water contact angle over 150o, further suggesting that the transparent coating owing superhydrophobic feature (Figure 3a). Theoretically, such characteristic of the coating should be attributed to the rough microstructure of the resulted paper surface, which is derived from the uniform distribution of nano-SiO2 particles on the cellulose fibers (Figure 3b,S6)30. The SEM images show that the SiO2 particles are uniformly distributed on the fibers surface without agglomeration, and the particles present in diameter of ~100nm, which full matches the schematic illustration of Figure 3b (Figure 3c). Note that the cellulose fibers entwined each other in diameter of ~tens of micrometers, which, combined with the well-defined nano-SiO2, builds the hierarchical structure similar to that of the lotus leaf surface, enabling air entrapped to resist water infiltration. In addition, the 17F substance in the colloidal emulsion could endow the paper fibers and the nano-SiO2 with hydrophobic component, whose function is similar to that of the wax composition of the lotus leaf. Consequently, both the fine micro/nano- hierarchical structure and the highly repellent component combiningly contribute to the surface of the cellulose paper with transparent and superhydrophobic feature. Similarly, when applying the stable colloidal emulsion to the wood surface, the water droplets on wood surface also exhibit in spherical form with water contact angle larger than 150o, indicating the wood endowed with superhydrohobicity (Figure 3d). The treated wood could


11


Page 12 of 42

highly repel water (Movie 3,4). Such feature should also be attributed to the nano-SiO2 particles uniformly coated on the micro-scale rough structure of the wood surface, which results in a micro/nano hierarchical structure (Figure 3e). The SEM images prove that the nano-SiO2 particles with average diameter of ~100nm are well distributed on wood cell wall without obvious aggregation (Figure 3f-j). The SEM images also present that the wood surface has micrometer scale roughness as the porous structure in diameter of several tens~hundreds micrometers (Figure 3g,i). Consequently, the coating of nano-SiO2 builds micro/nano- rough structure on wood surface, which is similar to that of the lotus leaf. In addition, the 17F composition in the colloidal emulsion imparts hydrophobic component to the rough surface. Both factors contribute transparent superhydrophobic surface to wood. Like wise, the spray coating enables other wood materials like medium density fiberboard (MDF) and plywood with similar superhydrophobic behavior due to the above two factors, which further indicates the wider applications of the spray coating on cellulose-based materials (Figure S7,8; Movie 5,6).


12

Page 13 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 3. Characterization for the transparent self-cleaning surface of paper and wood. (a) Digital photo of the superhydrophobic paper shows spherical water droplets stood on the surface without handwritings blurred; (b) schematic illustration to the microstructure of the self-cleaning


13


Page 14 of 42

surface of paper; (c) SEM images of the microstructure of the self-cleaning surface of paper; (d) Digital photo of the superhydrophobic wood shows spherical water droplets stood on the surface; (e) schematic illustration to the microstructure of the self-cleaning surface of wood; (f) schematic illustration and the corresponding SEM image of the 3D microstructure of the self-cleaning wood surface; (g) the SEM image of the longitudinal section of the self-cleaning wood; (h) the magnified SEM image of (g); (i) the SEM image of the cross section of the self-cleaning wood; (j) the magnified SEM image of (i). We explored the effects of colloidal emulsion concentration, 17F dosage and spraying quantity on the static water contact angle of paper and wood surface, and further determined the optimum craft (Figure 4). The results indicate that the water contact angles on paper surface are larger than 155o when the concentration of colloidal emulsion ranges from 10 mg/ml to 30 mg/ml, while the water contact angle of the wood surface varies from 148° to 157° (Figure 4a, Table 1). As when the concentration is 10 mg/ml and 25 mg/ml, the water contact angle on paper and wood reaches the maximum value, respectively, we therefore determine the concentration of 10 mg/ml and 25 mg/ml as the optimum value of paper and wood, respectively. Similarly, when the 17F dosage varies in the range of 30uL~105uL, all the water contact angles on either paper or wood are higher than 150o, we thus determine the 30uL as the optimum dosage (Figure 4b, Table 2). When the spraying quantity of the colloidal emulsion varies from 0.02ml/cm2 to 0.12ml/cm2, the water contact angles on both paper and wood fluctuate within the range of 144°~156° (Figure 4c, Table 3). When the spraying quantity of the colloidal emulsion respectively reaches 0.06ml/cm2 and 0.10ml/cm2 for paper and wood, their corresponding water contact angles match the maximum value. Consequently, on the basis of the above results (Figure 4a-c, Table 1), we preferably confirm 0.06ml/cm2 and 0.10ml/cm2 as the optimum spraying quantity of


14

Page 15 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


corresponding paper and wood, respectively. Note that the consumption of spray coating for the self-cleaning surface is far less than that of normal waterborne wood paint, and the raw materials for the spray coating are normal chemicals with moderate cost, positioning the ‘top-down’ spray coating of colloidal emulsion is a cheap way33. We sprayed the colloidal emulsion on paper and wood surface based on their above optimum crafts, and further tested their self-cleaning properties. Figure S9 shows that all the dynamic contact angles of paper, wood, MDF and plywood are lower than 10o. Figure 4d, S10 and Movie 7 present the process of water washing away the dusts on paper surface. The water droplets easily roll off as spherical form from the slightly sloping paper surface and take away the dusts, remaining clear handwritings on paper and thus indicating self-cleaning feature of the paper surface. Likewise, the dusts on wood surface are easily cleaned away by water droplets, therefore indicating superhydrophobic surface of wood with self-cleaning behavior (Figure 4e,S11, Movie 8). Similar self-cleaning behavior are also presented on MDF and plywood (Figure S12,S13). These above phenomena should be attributed to the fact that the interfacial interaction between superhydrophobic surface and polar dusts is lower than that between polar water droplets and polar dusts16. Table 1. Variations of water contact angles of the self-cleaning paper and wood depending on the concentration of the stable emulsion. Concentration of SiO2

Mean water contact

Error

Mean water contact angle

Error

emulsion (mg/ml)

angle of paper (o)

value

of wood (o)

value

10

156.3

0.25

148.2

0.275

20

156.7

0.1

153.7

0.267

25

156.2

0.15

156.4

0.25


15


30

156.3

0.27

Page 16 of 42

153.8

0.2

Table 2. Variations of water contact angles of the self-cleaning paper and wood depending on the 17F volume.

17F Volume (µL)

Mean water contact angle o

Error

Mean water contact angle o

Error

of paper ( )

value

of wood ( )

value

32

156.7

0.3

151.6

0.4

64

156.8

0.2

152.7

0.15

80

156

0.4

156.4

0.3

96

156.4

0.25

156.1

0.55

Table 3. Variations of water contact angles of the self-cleaning paper and wood depending on the spraying quantity of the stable emulsion. Spraying quantity of paper（mL/cm

2

Mean water contact angle of

Spraying Error value

Mean water

quantity of wood contact angle of

Error value

（mL/cm2）

wood (o)

0.3

0.012

144.2

0.133

149.6

0.1

0.024

152.4

0.167

0.063

152.4

0.2

0.036

155

0.067

0.084

156.3

0.133

0.048

155.9

0.1

）

paper (o)

0.021

145

0.042


16

Page 17 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 4. Craft optimization of the spray-coating process and the photos of the self-cleaning surfaces under the optimized crafts. (a) Chart to show the relationship between water contact angle and the concentration of stable emulsion; (b) chart to show the relationship between water contact angle and the 17F volume; (c) chart to show the relationship between water contact angle and the spraying quantity of the stable emulsion; (d) the digital photos to show the process of dusts on paper being cleaned away by water droplets; (e) the digital photos to show the process of dusts on wood being washed away by water droplets. We further explored the anti-bio-adhesive behavior of the superhydrophobic surfaces of paper and wood by conducting the experiments of decay resistance against fungus attack (Figure 5a-c, S14) . The results show that both the superhydrophobic paper and wood present cleaning


17


Page 18 of 42

surfaces without infection by the decay fungus (Figure 5b,S14), while the control paper and wood are infected by the decay fungus as they have gradually grown on the surfaces (Figure 5c,S14). Because the superhydrophobic paper and wood repel water, leading to lower moisture content (less than 10%) on surfaces and within the bodies, which destroys the substantial condition of high moisture content over 20% for fungus survival, the decay fungus therefore could not grow on the water-proof surfaces28. Based on the above results that the water-proof surfaces repel dust and resist microorganism attack, we can conclude that the transparent superhydrophobic coating could endow the cellulose-based materials with self-cleaning property, which makes them highly promising in applications of environmental hygiene and marine antifouling fields. In addition, the superhydrophobic coating could effectively preserve the mechanical properties of the cellulose-based materials when they expose to wet condition and improve their thermal stability than that of the untreated control materials. Figure 5d,e indicate that the superhydrophobic paper presents highest tensile strength of ~20MPa after immersion in water, which is almost equal to that of the dry paper, whereas the control paper in wet state shows almost zero tensile strength. Similarly, the superhydrophobic wood after soaking in water for 12 hours still has compression strength of 54 MPa, which is extremely close to that of the dry wood, while the control wood just remains compression strength of 30 MPa after water immersion (Figure 5g,h). These phenomena should be ascribed to the fact that the superhydrophobic surface effectively prevents water from penetrating into the paper and wood body, which thereby avoids the reduction of the interaction force between their components owing to the intervention of water moleculars53. Figure 5f and 5i show that each superhydrophobic paper or wood presents higher maximum thermal decomposition temperature than that of the control paper and wood,


18

Page 19 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


respectively, indicating that the spray coating improves the thermal stability of the cellulosebased materials. We further conducted a high-temperature test that the cellulose-based materials (control and superhydrophobic paper, and control and superhydrophobic wood) were placed in an oven at 210oC and -0.09MPa for 2hrs. The results show that the control paper and wood presents in darker color than that of superhydrophobic paper and wood, respectively, indicating improved thermal stability of the superhydrophobic cellulose-based materials (Figure S15). The results are mainly due to the higher thermal stability of the nano-SiO2 particles, which are uniformly distributed on the materials surface and thus renders less heat effectively transferred to the cellulose-based materials to cause their further thermal decomposition. Furthermore, we conducted the acid/alkaline resistance tests to verify the effectiveness of the surface superhydrophobicity under extreme conditions. Pure HAc solution and 1wt% NaOH solution (deionized water as solvent) are tested to drop on superhydrophobic wood and paper, and the results show that the droplets are easily rolled off the self-cleaning surface, indicating high resistance of the self-cleaning surface against acid and alkaline solution (Movie 9-12). Although great efforts have been made to improve the durability of the superhydrophobic surface, it still remains a big challenge54-55. We thus finally tested the impact resistance of the self-cleaning surface against water droplets. Movie 13 shows that the waterproof characteristic of the self-cleaning surface could be well preserved even after being impacted by continuous water flow for 480 min, suggesting excellent durability of the coating on the substance despite of the most probably physical interactions between coating and substance due to lack of reactive groups on the modified nano-SiO2.


19


Page 20 of 42

Figure 5. Comparison of anti-bio-adhesive behavior, mechanical property and thermal stability of the self-cleaning materials and the control materials. (a) Digital photo of the self-cleaning paper to show the water resistance; (b) digital photo of the self-cleaning paper to show the antibio-adhesive behavior; (c) digital photo of the control paper to exhibit the fungus attack; (d) digital photo of the self-cleaning paper to present the dust-proof behavior; (e) comparison of the tensile strength of the self-cleaning paper and the control paper after soaking in water for 12 hours; (f) comparison of the thermal stability of the self-cleaning paper and the control paper by TG/DTG curves; (g) digital photo to show the self-cleaning wood and the control wood against water; (h) comparison of the compression strength of the self-cleaning wood and the control wood after immersion in water for 12 hours; (i) comparison of the thermal stability of the selfcleaning wood and the control wood by TG/DTG curves.


20

Page 21 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


CONCLUSIONS In summary, we firstly developed a facile and scalable ‘top-down’ strategy to build transparent and superhydrophobic surface for cellulose-based materials by spray-coating stable emulsion consisting of synthesized nano-SiO2 particles and ethanol as solvent. The nano-SiO2 evenly distributed on cellulose-based materials’ surface with microscale roughness constitutes micro/nano- hierarchical structure, which imparts transparent superhydrophobic coating to the materials with static water contact angle larger than 150o and dynamic contact angle less than 10o. The spray coating endows the materials with integrated advantages of light transparency, dust proof, anti-bio-adhesive behavior and water repellency, indicating self-cleaning surface built on the materials. Such behavior well preserves the mechanical properties of paper and wood when exposed to wet conditions, and improves their thermal stability, positioning such cellulose-based materials as structural or bioscaffold materials capable of being applied in harsh environment to resist water, dusts, microorganisms and even acid or alkaline. This facile, low-cost and stable emulsion could be large-scalely applied as a spray coating way to wider range of materials for transparent self-cleaning surface. Experimental Section Materials and Chemicals Poplar wood (Populus ussuriensis Kom) was brought from Maoershan plantation (Harbin China). Each sample for property evaluation was cut from the lumber and oven-dried at 105 ℃ for 24 h before use. Paper was normal printing paper. Anhydrous Ethanol, Acetone, Toluene (all purchased from Tianjin Kemio Chemical Industry Co. Ltd., Tianjin China), Ammonia (NH3·H2O, 25%) ( Yantai Laiyang Kant Chemical Industry Co.Ltd., Yantai China), Tetraethyl Orthosilicate


21


Page 22 of 42

(TEOS) (Shanghai Macklin Biochemical Co. Ltd., Shanghai China), Polydimethylsiloxane (PDMS) and 1H,1H,2H,2H-Perfluorodecyltrimethoxysilane (17F) (Shanghai Hanhong Chemical Co. Ltd., Shanghai China), were directly used without further purification. The deionized (DI) water was self-made. Synthesis of nano-SiO2 particles ① Calculated amounts of anhydrous ethanol and deionized water were mixed together, followed by adding TEOS into the solution; ② A certain amount of ammonia was added into the above mixed solution in 10 min under stirring rate of 700rpm; ③ the solution was further stirred for 1h and gradually became into slight blue color; ④ the derived emulsion was centrifuged at 8000rpm for 10 min, and the nano-SiO2 particles were finally obtained after the centrifuged particles being dried at 103oC for 12h. Modification of the nano-SiO2 particles Calculated amounts of nano-SiO2 particles and PDMS were mixed in toluene and magnetically stirred at room temperature for 72h; ② the emulsion was centrifuged at 8000rpm for 10min and then repetitively washed

by acetone for three times; ③ The centrifuged

nanoparticles were finally oven-dried under vacuum condition of 0.09 MPa and temperature of 103oC for 12 hours. Preparation of the nano-SiO2 colloidal emulsion ① Certain amounts of PDMS-modified nano-SiO2 particles were dispersed in anhydrous ethanol, and calculated amounts of 17F was added into the above solution to form a mixed emulsion; ②


22

Page 23 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


the mixed solution was treated by ultrasonic under 500MHz for 30min to form a uniformly dispersed colloidal emulsion that could be stored at room temperature for more than one year. The spray coating process The stable colloidal emulsion was first poured into a spraying equipment and then sprayed onto the samples under 0.8MPa condition. The distance of the spraying equipment and the samples is about 15cm, and the samples are inclined at 45o for spray coating. The spraying quantity of the stable emulsion are further studied in terms of the emulsion volume per square centimeter of the sample surface. Measurements and Characterizations The colloidal emulsion was characterized by Transmission Electron Microscope (TEM, JEM1400, JEOL USA Inc., Peabody, Massachusetts) and Atomic Force Microscope (AFM, NaioAFM, Nanosurf AG, Liestal, Switzerland). The self-cleaning surface of wood and paper were observed by scanning electron microscopy (FE-SEM, JEM-6610LV, JEOL USA Inc., Peabody, Massachusetts). The surface components of the nano-SiO2 were characterized by X-ray Photoelectron Spectroscopy (XPS，Escalab 250Xi, Thermo Scientific Inc., Massachusetts) and Fourier Transform Infrared Spectroscopy (FTIR, Nicolet Magna 560, Thermo Nicolet Inc., Madison, WI). The binding energies of X-ray photoelectron spectroscopy were referenced to the C 1s neutral carbon peak at 284.8 eV. The test parameters included energy resolution of 0.8ev, sensitivity of 80kcps, angular resolution of 45o, and vacuum degree of the analysis chamber of 3.0*10-7Pa. The FTIR spectra was recorded in the range from 4000 to 500 cm-1 with resolution of 4 cm-1. The thermal stability of the spray-coated samples were tested by a Thermogravimetric Analyzer (TGA Q500, Waters, New Castle, DE) instrument. 5~10 mg powders were employed


23


Page 24 of 42

for the test with conditions of continuous nitrogen flow, heat rate of 10 oC/min, and the temperature ranged from 50 to 675 oC. The contact angles of the water droplets were measured at room temperature using a contact angle goniometer (OCA-15EC,Beijing Eastern-Dataphy Instruments Inc.,China). 3 uL deionized water was employed for the measurement. Three times measurements were taken at different points of each sample surface, from which the average contact angle was determined. Dynamic water contact angle was captured by triangulation method. The tests of tensile strength and compression strength were performed using a mechanical testing apparatus ( A1-7000S, Gotech Testing Machines Inc., Taiwan, China). For each sample, the test was carried out in three times, from which the average result was calculated. Decay resistance test was conducted using a brown fungus (Gloeophyllum trabeum (Pers. ex Fr.) Murr.) according to the previous reported method26-27. ASSOCIATED CONTENT Supporting Information (Figure S1) AFM characterization of the diameter of nano-SiO2 particles, (Figure S2) Si 2p high-resolution scan XPS spectra of the nano-SiO2 modified by PDMS and 17F, (Figure S3) FTIR spectra of the nano-SiO2 modified by PDMS and 17F, (Figure S4) Digital photos and transmittance curve to show the transparency of the superhydrophobic coating on nanocellulose paper, (Figure S5) transmittance curve and digital photos to show the transparency of the superhydrophobic coating on glass, (Figure S6) Digital photo of the self-cleaning paper and the SEM images of the corresponding microstructure, (Figure S7) Digital photo of the self-cleaning medium density fiberboard (MDF) and the SEM images of the corresponding microstructure, (Figure S8) Digital photo of the self-cleaning plywood and the SEM images of the corresponding


24

Page 25 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


microstructure, (Figure S9) The dynamic WCA of different cellulose-based materials with the self-cleaning coating, (Figure S10) Digital photos to show the process of the dusts on the selfcleaning paper being washed away by water droplets, (Figure S11) Digital photos to show the process of the dusts on the self-cleaning wood being washed away by water droplets, (Figure S12) Digital photos to show the process of the dusts on the self-cleaning MDF being washed away by water droplets, (Figure S13) Digital photos to show the process of the dusts on the self-cleaning plywood being washed away by water droplets, (Figure S14) Comparison of the anti-bioadhesive behavior of the self-cleaning wood and the control wood, (Figure S15) Digital photos to show the thermal stability difference of the control samples and the superhydrophobic samples in terms of their color difference. (Movie 1) Superhydrophobic paper to show the transparency of the spray coating, (Movie 2) Comparison of the self-cleaning nanocellulose paper and the control nanocellulose paper to show the transparency of the coating, (Movie 3) Comparison of water repellency of the self-cleaning wood and the control wood, (Movie 4) High waterproof of the self-cleaning wood, (Movie 5) Self-cleaning MDF, (Movie 6) Self-cleaning plywood, (Movie 7) The self-cleaning behavior of the spray-coated paper against dusts, (Movie 8) The self-cleaning behavior of the spray-coated wood against dusts, (Movie 9) The acid-resist behavior of the spray-coated paper, (Movie 10) The acid-resist behavior of the spray-coated wood, (Movie 11) The alkaline-resist behavior of the spray-coated paper, (Movie 12) The alkaline-resist behavior of the spray-coated wood, (Movie 13) Impact resistance of the self-cleaning surface of wood against continuous water flow for 480 min to show the coating durability. AUTHOR INFORMATION Corresponding Authors


25


Page 26 of 42

*E-mail: [email protected], [email protected]; [email protected] Notes The authors declare no competing financial interest. Author contributions Jie Wei, Gang Zhang, Xiaoying Dong, Jing Dong and Yongfeng Li designed the experiment. Jie Wei and Gang Zhang performed the whole experiments. Jing Dong helped to analyze the characterizations. Huatian Wang gave many suggestions on this study. Yunlong Guo and Xiao Zhuo drew the figures. Changgui Li helped to conduct the experiment of anti-bio-adhesive behavior. Jie Wei, Gang Zhang and Hui Liang carried out evaluation of mechanical properties and thermal stability. Canghai Li provided the wood samples for the whole experiment. Jie Wei, Xiaoying Dong and Yongfeng Li wrote the paper. Everybody comments on the final manuscript. a

Jie Wei, Gang Zhang and Jing Dong contributed equally to this work.

ACKNOWLEDGEMENT S We acknowledge the financial supports from the Natural Science Foundation of Shandong Province, Doctoral Branch (Grant. No. ZR2017BC042), and Innovation Project of Shandong Provincial Forestry Science and Technology (Grant. No. LYCX10-2018-50), and Key Special Foundation for the National Key Research and Development Program of China (Grant. No. 2016YFD0600704), and National Natural Science Foundation of China (Grant. No. 31700497), and Project of the Shandong Province Higher Educational Science and Technology Program (Grant. No. J15LC13).


26

Page 27 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


REFERENCES 1. Link, H. S.; Schmitt, R. J. Iron, Carbon Steel, and Alloy Steel. Materials of Construction Review. Ind. Eng. Chem. 1961, 53 (7), DOI: 10.1021/ie50619a036. 2. Seymour, R. B. Plastics. Materials of Construction Review. Ind. Eng. Chem. 1961, 53 (10), DOI: 10.1021/ie50622a034. 3. Zhang, X. F.; Li, Q. W.; Holesinger, T. G.; Arendt, P. A.; Huang, J. Y.; Clapp, T. G.; Depaula, R. F.; Liao, X. Z.; Zhao, Y. H.; Zheng, L. X.; Peterson, D. E.; Zhu, Y. T. Ultrastrong, Stiff, and Lightweight Carbon-Nanotube Fibers. Adv. Mater. 2007, 19, DOI: 10.1002/adma.200700776. 4. Kelly, J. C.; Sullivan, J. L.; Burnham, A.; Elgowainy, A. Impacts of Vehicle Weight Reduction via Material Substitution on Life-Cycle Greenhouse Gas Emissions. Environ. Sci. Technol. 2015, 49 (20), DOI: 10.1021/acs.est.5b03192. 5. Serrano-Ruiz, C. J.; West, M. R.; Dumesic, A. J. Catalytic Conversion of Renewable Biomass Resources to Fuels and Chemicals. Annu. Rev. Chem. Biomol. 2010, 1, DOI: 10.1146/annurevchembioeng-073009-100935. 6. Zhu, H.; Luo, W.; Ciesielski, P.; Fang, Z.; Zhu, J.; Henriksson, G.; Himmel, M.; Hu, L. Wood-Derived Materials for Green Electronics, Biological Devices, and Energy Applications. Chem. Rev. 2016, 116 (16), DOI: 10.1021/acs.chemrev.6b00225. 7. Moon, R.; Martini, A.; Nairn, J.; Simonsen, J.; Youngblood, J. Cellulose Nanomaterials Review: Structure, Properties and Nanocomposites. Chem. Soc. Rev. 2011, 40 (7), DOI: 10.1039/C0CS00108B.


27


Page 28 of 42

8. Zeng, J. B.; He, Y. S.; Li, S. L.; Wang, Y. Z. Chitin Whiskers: An Overview. Biomacromolecules, 2012, 13 (1), DOI: 10.1021/bm201564a. 9. Klemm, D.; Kramer, F.; Moritz, S.; Lindström, T.; Ankerfors, M.; Gray, D.; Dorris, A. Nanocelluloses: A New Family of Nature-based Materials. Angew. Chem. Int. Edit. 2011, 50 (24), DOI: 10.1002/anie.201001273. 10. Zhu, M. W.; Wang, Y. L.; Zhu, S. Z.; Xu, L. S.; Jia, C.; Dai, J. Q.; Song, J. W.; Yao, Y. G.; Wang, Y. B.; Li, Y. F.; Henderson, D.; Luo, W.; Li, H.; Minus, M. L.; Li T.; Hu L. B. Anisotropic, Transparent Films with Aligned Cellulose Nanofibers. Adv. Mater. 2017, 29 (21), DOI: 10.1002/adma.201606284. 11. Zhuo, X.; Wei, J.; Xu, J. F.; Pan, R. T.; Zhang, G.; Guo, Y. L.; Dong, X. Y.; Long, L.; Li Y. F. Nanocellulose Isolation from Amorpha Fruticosa by An Enzyme-assisted Pretreatment. Appl. Environ. Biotech. 2017, 2 (1), DOI: 10.26789/AEB.2017.01.005. 12. Ming, S. Y.; Chen, G.; He, J. H.; Kuang, Y. D.; Liu, Y.; Tao, R. Q.; Ning, H. L.; Zhu, P. H.; Liu, Y. Y.; Fang, Z. Q. Highly Transparent and Self-Extinguishing Nanofibrillated CelluloseMonolayer

Clay

Nanoplatelet

Hybrid

Films.

Langmuir

2017,

33

(34),

DOI:

10.1021/acs.langmuir.7b01665. 13. Zhang, Z.; Wu, Q.; Song, K.; Ren, S.; Lei, T. Using Cellulose Nanocrystals as A Sustainable Additive to Enhance Hydrophility, Mechanical and Thermal Properties of Poly (vinylidiene fluoride)/Poly (methyl methacrylate) Blend. ACS Sustain. Chem. Eng. 2015, 3 (4), DOI: 10.1021/sc500792c.


28

Page 29 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


14. Shaghaleh, H.; Xu, X.; Wang, S. Current Progress in Production of Biopolymeric Materials Based on Cellulose, Cellulose Nanofibers, and Cellulose Derivatives. RSC Adv. 2018, 8 (2), 10.1039/C7RA11157F. 15. Song, J. W.; Chen, C. J.; Zhu, S. Z.; Zhu, M. W.; Dai, J. Q.; Ray, U.; Li, Y. J.; Kuang, Y. D.; Li, Y. F.; Quispe, N.; Yao, Y. G.; Gong, A.; Leiste, U. H.; Bruck, H. A.; Zhu, J. Y.; Vellore, A.; Li, H.; Minus, M. L.; Jia, Z.; Martini, A.; Li, T.; Hu, L. B. Processing Bulk Natural Wood into A High-performance Structural Material. Nature 2018, 554, DOI: 10.1038/nature25476. 16. Ras, R. H. A.; Pradeep, T. Organic Solvent-Free Fabrication of Durable and Multifunctional Superhydrophobic Paper from Waterborne Fluorinated Cellulose Nanofiber Building Blocks. ACS Nano 2017, 11 (11), DOI: 10.1021/acsnano.7b05170. 17. Huang, X.; Wang, A.; Xu, X.; Liu, H.; Shang, S. Enhancement of Hydrophobic Properties of Cellulose Fibers via Grafting with Polymeric Epoxidized Soybean Oil. ACS Sustain. Chem. Eng. 2017, 5 (2), DOI: 10.1021/acssuschemeng.6b02359. 18. Zhu, H.; Fang, Z.; Preston, C.; Li, Y.; Hu, L. Transparent Paper: Fabrications, Properties, and Device Applications. Energy Environ. Sci. 2014, 7 (1), DOI: 10.1039/C3EE43024C. 19. Jiang, F.; Hsieh, Y. Holocellulose Nanocrystals: Amphiphilicity, Oil/Water Emulsion, and Self-assembly. Biomacromolecules 2015, 16 (4), DOI: 10.1021/acs.biomac.5b00240. 20. Chen, T.; Xie, Y.; Cai, L.; Zhuang, B.; Wang, X.; Wu, Z.; Niu, M.; Lin, M. Mesoporous Aluminosilicate Material with Hierarchical Porosity for Ultralow Density Wood Fiber Composite

(ULD_WFC).

ACS

Sustain.

Chem.

Eng.

2016,

4

(7),

DOI:

10.1021/acssuschemeng.6b00691.


29


Page 30 of 42

21. Song, J. W.; Chen, C. J.; Yang, Z.; Kuang, Y. D.; Li, T.; Li, Y. J.; Huang, H.; Kierzewski, I.; Liu, B. Y.; He, S. M.; Gao, T. T., Yuruker, S. U.; Gong, A.; Yang, B.; Hu, L. B. Highly Compressible, Anisotropic Aerogel with Aligned Cellulose Nanofibers. ACS Nano, 2018, 12 (1), DOI: 10.1021/acsnano.7b04246. 22. Huang, X. J.; Li, Q. G.; Liu, H.; Shang, S. B.; Shen, M. G.; Song, J. Oil-in-Water Emulsions Stabilized by Saponified Epoxidized Soybean Oil-Grafted Hydroxyethyl Cellulose. J. Agric. Food Chem. 2017, 65 (17), DOI: 10.1021/acs.jafc.7b00662. 23. Ning, H. L.; Zeng, Y.; Kuang, Y. D.; Zheng, Z. K.; Zhou, P. P.; Yao, R. H.; Zhang, H. K.; Bao, W. Z.; Chen, G.; Fang, Z. Q.; Peng J. B. Room-Temperature Fabrication of HighPerformance Amorphous In-Ga-Zn-O/Al2O3 Thin-Film Transistors on Ultrasmooth and Clear Nanopaper. ACS Appl. Mater. Interfaces 2017, 9 (33), DOI: 10.1021/acsami.7b07525. 24. Jiang F.; Hsieh, Y. L. Cellulose Nanofibril Aerogels: Synergistic Improvement of Hydrophobicity, Strength, and Thermal Stability via Cross-Linking with Diisocyanate. ACS Appl. Mater. Interfaces 2017, 9 (3), DOI: 10.1021/acsami.6b13577. 25. Zhu, M.; Song, J.; Li, T.; Gong, A.; Wang, Y.; Dai, J.; Yao, Y.; Luo, W.; Henderson, D.; Hu, L. Highly Anisotropic, Highly Transparent Wood Composites. Adv. Mater. 2016, 28 (26), DOI: 10.1002/adma.201600427. 26. Li, Y. F.; Dong, X. Y.; Liu, Y. X.; Li, J.; Wang, F. H. Improvement of Decay Resistance of Wood via Combination Treatment on Wood Cell Wall: Swell-bonding with Maleic Anhydride and Graft Copolymerization with Glycidyl Methacrylate and Methyl Methacrylate. Int. Biodeter. Biodegr. 2011, 65 (7), DOI: 10.1016/j.ibiod.2011.08.009.


30

Page 31 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


27. Dong, X. Y.; Zhuo, X.; Wei, J.; Zhang, G.; Li, Y. F. Wood-based Nanocomposite Derived by In-situ Formation of Organic-inorganic Hybrid Polymer within Wood via A Sol-gel Method. ACS Appl. Mater. Interfaces 2017, 9 (10), DOI: 10.1021/acsami.7b01174. 28. Dong, X. Y.; Zhuo, X.; Liu, C.; Wei, J.; Zhang, G.; Pan, R. T.; Li, Y. F. Improvement of Decay Resistance of Wood by In-situ Hybridization of Reactive Monomers and Nano-SiO2 within Wood. Appl. Environ. Biotech. 2016, 1 (2), DOI: 10.18063/AEB.2016.02.008.. 29. Zhou, C.; Shi, Q.; Guo, W.; Terrell, L.; Qureshi, A.; Hayes, D.; Wu, Q. Electrospun BioNanocomposite Scaffolds for Bone Tissue Engineering by Cellulose Nanocrystals Reinforcing Maleic Anhydride Grafted PLA. ACS Appl. Mater. Interfaces 2013, 5 (9), DOI: 10.1021/am4005072. 30. Teisala, H.; Tuominen, M.; Kuusipalo, J. Superhydrophobic Coatings on Cellulose-Based Materials: Fabrication, Properties, and Applications. Adv. Mater. Interfaces 2014, 1 (1), DOI: 10.1002/admi.201300026. 31. Li, Y. F.; Wu, Q. L.; Li, J.; Liu, Y. X.; Wang, X. M.; Liu, Z. B. Improvement of Dimensional Stability of Wood via Combination Treatment: Swelling with Maleic Anhydride and Grafting with Glycidyl Methacrylate and Methyl Methacrylate. Holzforschung 2012, 66, DOI: 10.1515/HF.2011.123. 32. He, M.; Xu, M.; Zhang, L. N. Controllable Stearic Acid Crystal Induced High Hydrophobicity on Cellulose Film Surface. ACS Appl. Mater. Interfaces 2013, 5 (3), DOI: 10.1021/am3026536.


31


Page 32 of 42

33. Liu, H.; Song, J.; Shang, S. B.; Song, Z. Q.; Wang, D. Cellulose Nanocrystal/Silver Nanoparticle Composites as Bifunctional Nanofillers within Waterborne Polyurethane. ACS Appl. Mater. Interfaces 2012, 4 (5), DOI: 10.1021/am3000209. 34. Dong, X. Y.; Sun, T. P.; Liu, Y. X.; Li, C. H.; Li, Y. F. Structure and Properties of Polymerimpregnated Wood Prepared by In-situ Polymerization of Reactive Monomers. BioResources 2015, 10 (4), DOI: 10.15376/biores.10.4.7854-7864. 35. Wang, S. T.; Liu, K. S.; Yao, X.; Jiang, L. Bioinspired Surfaces with Superwettability: New Insight on Theory, Design, and Applications. Chem. Rev. 2015, 115 (16), DOI: 10.1021/cr400083y. 36. Su, B.; Tian, Y.; Jiang, L. Bioinspired Interfaces with Superwettability: From Materials to Chemistry. J. Am. Chem. Soc. 2016, 138 (6), DOI: 10.1021/jacs.5b12728. 37. Lu, P.; Huang, Q.; Mukherjee, A.; Hsieh, Y. L. SiCO-doped Carbon Fibers with Unique Dual Superhydrophilicity/Superoleophilicity and Ductile and Capacitance Properties. ACS Appl. Mater. Interfaces 2010, 2 (12), DOI: 10.1021/am100918x. 38. Tian, Y.; Jiang, L. Wetting: Intrinsically Robust Hydrophobicity. Nat. Mater. 2013, 12 (4), DOI: 10.1038/nmat3610. 39. Sasaki,

K.;

Tenjimbayashi,

M.;

Manabe,

K.;

Shiratori,

S.

Asymmetric

Superhydrophobic/Superhydrophilic Cotton Fabrics Designed by Spraying Polymer and Nanoparticles. ACS Appl. Mater. Interfaces 2016, 8 (1), DOI: 10.1021/acsami.5b09782.


32

Page 33 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


40. Arslan, O.; Aytac, Z.; Uyar, T. Superhydrophobic, Hybrid, Electrospun Cellulose Acetate Nanofibrous Mats for Oil/Water Separation by Tailored Surface Modification. ACS Appl. Mater. Interfaces 2016, 8 (30), DOI: 10.1021/acsami.6b05429. 41. Sas, I.; Gorga, R. E.; Joines, J. A.; Thoney, K. A. Literature Review on Superhydrophobic Self-Cleaning Surfaces Produced by Electrospinning. J. Polym. Sci. Pol. Phys. 2012, 50 (12), DOI: 10.1002/polb.23070. 42. Francisco, R. D.; Tiemblo, P.; Hoyos, M.; Arellano, C. G.; Garc í a, N.; Berglund, L.; Synytska

A.

Multipurpose

Ultra

and

Superhydrophobic

Surfaces

Based

on

Oligodimethylsiloxane-Modified Nanosilica. ACS Appl. Mater. Interfaces 2014, 6 (12), DOI: 10.1021/am504886y. 43. Wen, L. P.; Tian, Y.; Jiang, L. Bioinspired Super-wettability from Fundamental Research to Practical Applications. Angew. Chem. Int. Edit. 2015, 54 (11), DOI: 10.1002/anie.201409911. 44. Chen, S.; Song, Y.; Xu, F. Highly Transparent and Hazy Cellulose Nanopaper Simultaneously with A Self-Cleaning Superhydrophobic Surface. ACS Sustainable Chem. Eng. 2018, 6 (4), DOI: 10.1021/acssuschemeng.7b04814. 45. Li, T. J.; Paliy, M.; Wang, X. D.; Kobe, B.; Lau, W. M.; Yang, J. A Facile One-Step Photolithographic Method for Engineering Hierarchically Nano/Micro-structured Transparent Superamphiphobic

Surfaces.

ACS

Appl.

Mater.

Inter.

2015,

7

(20),

DOI:

10.1021/acsami.5b01926.


33


Page 34 of 42

46. Lai, Y. K.; Tang, Y. X.; Gong, J. J.; Gong, D. G,; Chi, L. F.; Lin, C. J.; Chen, Z. Transparent Superhydrophobic/Superhydrophilic TiO2-Based Coatings for Self-cleaning and Anti-fogging. J. Mater. Chem. 2012, 22 (15), DOI: 10.1039/C2JM16298A. 47. Gao, S. W.; Dong, X. L.; Huang, J. Y.; Li, S. H.; Li, Y. W.; Chen, Z.; Lai, Y. K. Rational Construction of Highly Transparent Superhydrophobic Coatings Based on A Non-particle, Fluorine-free and Water-rich System for Versatile Oil-water Separation. Chem. Eng. J. 2018, 333, DOI: 10.1016/j.cej.2017.10.006. 48. Liu, H.; Huang, J. Y.; Chen, Z.; Chen, G. Q.; Zhang, K. Q.; Al-Deyab, S. S.; Lai, Y. K. Robust Translucent Superhydrophobic PDMS/PMMA Film by Facile One-step Spray for SelfCleaning

and

Efficient

Emulsion

Separation.

Chem.

Eng.

J.

2017,

330,

DOI:

10.1016/j.cej.2017.07.114. 49. Deng, X.; Mammen, L.; Butt, H. J.; Vollmer, D. Candle Soot as A Template for A Transparent

Robust

Superamphiphobic

Coating.

Science

2012,

335

(6064),

DOI:

10.1126/science.1207115. 50. Ebert, D.; Bhushan, B. Transparent, Superhydrophobic, and Wear-Resistant Surfaces Using Deep Reactive Ion Etching on PDMS Substrates. J. Colloid Interf. Sci. 2016, 481, DOI: 10.1016/j.jcis.2016.07.035. 51. Bravo,

J.; Zhai, L.; Wu, Z. Z.; Cohen, R. E.;

Rubner, M. F. Transparent

Superhydrophobic Films Based on Silica Nanoparticles. Langmuir 2007, 23 (13), DOI: 10.1021/la070159q.


34

Page 35 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


52. Nogi, M.; Iwamoto, S.; Nakagaito, A.; Yano, H. Optically Transparent Nanofiber Paper. Adv. Mater. 2009, 21 (16), DOI: 10.1002/adma.200803174. 53. Francisco, R. D.; Hoyos, M.; Garc í a, N.; Tiemblo, P. Superhydrophobic and Highly Luminescent Polyfluorene/Silica Hybrid Coatings Deposited onto Glass and Cellulose-Based Substrates. Langmuir 2015, 31 (12), DOI: 10.1021/acs.langmuir.5b00293. 54. Liu, H.; Huang, J. Y.; Li, F. Y.; Chen, Z.; Zhang, K. Q.; Al-Deyab, S. S.; Lai, Y. K. Multifunctional Superamphiphobic Fabrics with Asymmetric Wettability for One-Way Fluid Transport and Templated Patterning. Cellulose 2017, 24 (2), DOI: 10.1007/s1057. 55. Cao, C. Y.; Ge, M. Z.; Huang, J. Y.; Li, S. H.; Deng, S.; Zhang, S. N.; Chen, Z.; Zhang, K. Q.; Al-Deyab, S. S.; Lai, Y. K. Robust Fluorine-Free Superhydrophobic PDMSOrmosil@Fabrics for Highly Effective Self-Cleaning and Efficient Oil-Water Separation. J. Mater. Chem. A 2016, 4 (31), DOI: 10.1039/C6TA04420D.


35


Page 36 of 42

Table of Content

A facile, cheap and scalable ‘top-down’ strategy to build transparent self-cleaning surface for cellulose-based materials, which meets sustainable development.


36

Page 37 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


A facile, cheap and scalable ‘top-down’ strategy to build transparent self-cleaning surface for cellulose-based materials, which meets sustainable development. 148x68mm (300 x 300 DPI)



Figure 1. Schematic illustration to the spray-coating way for cellulose-based materials. 150x96mm (300 x 300 DPI)


Page 38 of 42

Page 39 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 2. Characterization of the synthesized nano-SiO2 and the surface’s modification. 150x107mm (300 x 300 DPI)



Figure 3. Characterization for the transparent self-cleaning surface of paper and wood. 146x166mm (300 x 300 DPI)


Page 40 of 42

Page 41 of 42 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 5. Comparison of anti-bio-adhesive behavior, mechanical property and thermal stability of the selfcleaning materials and the control materials. 150x98mm (300 x 300 DPI)


Facile, Scalable Spray Coating of Stable Emulsion for Transparent

Recommend Documents