RSC Advances PAPER View Article Online View Journal | View Issue Amphiphobic nanocellulose-modified paper: fabrication and evaluation† Cite this: RSC Adv.,2016,6,13328 Patchiya Phanthong,a Guoqing Guan,*ab Surachai Karnjanakom,a Xiaogang Hao,c Zhongde Wang,c Katsuki Kusakabed and Abuliti Abudulaab Amphiphobic nanocellulose-modified paper with high durability is successfully fabricated using a facile two-step method. Firstly, nanocellulose-modified paper is prepared through dipping filter paper, i.e., glass microfiber (GM) filter paper and polytetrafluoroethylene (PTFE) filter paper in a dilute nanocellulose dispersed solution. Subsequently, the nanocellulose-coated paper is treated with trichloro(1H,1H,2H,2H- tridecafluoro-n-octyl)silane (FOTS) via chemical vapor deposition. The obtained paper is found to have superhydrophobicity and oleophobicity, repelling both polar and non-polar liquids, on which the drops of water and non-polar liquids with high molecular weight become marble shaped, and the contact angles of water and n-hexadecane reach 156 and 144, respectively. Furthermore, such amphiphobic nanocellulose-modified papers exhibit excellent surface durability in several environments including at various temperatures, and in acid and alkaline solutions, salt solutions and seawater. In addition, such Received 25th November 2015 amphiphobic nanocellulose-modified papers show good repellant properties for several kinds of liquids Accepted 20th January 2016 from our daily life. With outstanding protection to a diverse range of liquids, the amphiphobic DOI: 10.1039/c5ra24986d nanocellulose-modified paper can be applied in the fields of self-cleaning, anti-bacterial, and anti- www.rsc.org/advances corrosion materials. 1 Introduction On the contrary, a solid surface with oil repellent properties is named an oleophobic surface. It is expected that materials can In nature, lotus leaves show self-cleaning properties, on which be developed with an amphiphobic surface, on which both water drops can be removed quickly. This phenomenon water and oil can be repelled quickly. In other words, an inspired us to fabricate similar materials with water repellent amphiphobic surface combines hydrophobicity and oleopho- properties. A simple and quantitative indicator to evaluate the bicity, resulting in a surface with super anti-wetting properties. Published on 25 January 2016. Downloaded by Taiyuan University of Technology 08/08/2016 04:39:29. tendency of the repelling or wetting properties of a liquid is the This anti-wetting property relates to various advantages such as contact angle of the liquid on the solid surface. A hydrophilic being self-cleaning, anti-bacterial, anti-reective, corrosion solid surface is a surface wetted from water spreading without resistant and so on.8,9 However, the development of such kinds the formation of any droplets or the surface with a water contact of materials is full of more challenges since the lower surface angle of less than 90; in contrast, a hydrophobic solid surface tension of oil generally leads to a higher solid surface attraction – repels the spreading of water generally and has a water contact and as a result oil can easily wet a superhydrophobic surface.8 12 angle higher than 90. Recently, it has been most popular to To fabricate articial superhydrophobic surfaces, two impor- develop a solid surface with superhydrophobicity, on which tant factors, i.e., roughness and surface energy, need to be water apparently forms a droplet, easily slides off, and the considered. For the surface roughness, Cassie et al.13 addressed formed water droplet has a contact angle of larger than 150.1–7 the wetting theory modelling the wettability of a rough surface. At the small protrusions of a rough surface, it cannot be lled by liquid but can be lled by air, thus only the top areas of a rough aGraduate School of Science and Technology, Hirosaki University, 1-Bunkyocho, surface are wetted by liquid.1,5,6 For the surface energy, liquids Hirosaki 036-8560, Japan with lower surface tension than the critical surface tension of bNorth Japan Research Institute for Sustainable Energy (NJRISE), Hirosaki University, the substrate will wet the surface.2 Generally, superhydrophobic 2-1-3, Matsubara, Aomori 030-0813, Japan. E-mail: [email protected]; Fax: +81- surfaces are extremely low surface energy materials, especially 17-735-5411; Tel: +81-17-762-7756 À1 14 cDepartment of Chemical Engineering, Taiyuan University of Technology, Taiyuan lower than the surface tension of water (72.1 mN m ), thus it 030024, China will not be wetted by water. However, to fabricate super- dDepartment of Nanoscience, Sojo University, 4-22-1 Ikeda, Nishi-ku, Kumamoto 860- oleophobic surfaces, other factors which can protect from oil 0082, Japan penetrating the texture should be considered.8,10–12 In addition, † Electronic supplementary information (ESI) available. See DOI: the lower surface tension of oil, i.e., n-hexadecane (27.47 mN 10.1039/c5ra24986d 13328 | RSC Adv.,2016,6, 13328–13334 This journal is © The Royal Society of Chemistry 2016 View Article Online Paper RSC Advances À m 1),14 than water is another challenge for developing the low transform infrared spectroscopy (FTIR) for investigation of the surface tension of superoleophobic surfaces. To fabricate wettability, morphology, and chemical structure of the amphi- superamphiphobic surfaces, a specic combination of low phobic surface. The durability of the amphiphobic surface energy and reentrant surface structure is needed.10–12 Li nanocellulose-modied paper was also tested in various envi- et al.11 developed a method to design and create cellulose-based ronments including at various temperatures, and in acid and natural materials with superamphiphobic properties by alkaline solutions, salt solutions and seawater. In addition, 10 combining the control of cellulose ber size and structure using kinds of liquids from our daily life were used to test its repellant plasma etching and uoropolymer deposition. The obtained properties. It is expected that this will become a facile method handsheets exhibited contact angles of greater than 150 for to fabricate amphiphobic papers with high durability. water, ethylene glycol, motor oil and n-hexadecane. Jin et al.15 also prepared amphiphobic cellulose-based materials using 2 Experimental liquid treatments to generate the necessary roughness, followed 2.1 Materials by self-assembling a 1H,1H,2H,2H-peruorooctyl trimethox- ysilane (PFOTMS) monolayer onto the surface. Nanocellulose from bleached hardwood was provided by Daio Nanocellulose has recently gained great attention from Paper Corporation. GM lter paper (pore size: 1.6 mm; GF/A, researchers and industry because it has some unique properties Whatman) and hydrophilic PTFE lter paper (pore size: 0.1 including high tensile modulus, high specic surface area, mm; H010A047A, Advantec) were used as substrates. FOTS (98%, biodegradability, biocompatibility and sustainability.16,17 Espe- TCI, Japan) was used as received. Sulfuric acid aqueous solution cially, nanocellulose has nanoscale dimensions and is rich in (47 wt%), sodium hydroxide, sodium chloride, n-hexane, n- hydroxyl groups with good affinity to a variety of materials. octane, n-hexadecane, toluene, ethylene glycol, and formamide Thus, it can be applied to make high quality paper with special were purchased from Wako Pure Chemical Ltd. and used surface properties or modify other solid surfaces.18 Using without any further purication. Vacuum pump oil (ultragrade nanocellulose to increase the roughness and reactivity of 15) was purchased from Edwards Ltd. Seawater was collected surfaces is an attractive idea to modify substrates for achieving from Aomori Bay, Aomori City, Japan, and also used for testing amphiphobicity using a natural source. Meanwhile, most without any pretreatment. 19,20 research has used hard particles such as SiO2 particles, 21 22 per uoropolyether (PFPE), and Al2O3 nanoparticles for 2.2 Preparation of nanocellulose-modi ed substrates surface modi cation to achieve superhydrophobicity and The substrates (GM lter paper and hydrophilic PTFE lter oleophobicity. paper) were cleaned by soaking them in ethanol for 5 h followed To decrease the surface tension of substrates, silane is one by drying them at 110 C for 12 h. Various concentrations (0.01, kind of chemical which interacts with substrates and achieves 0.1 and 0.5 wt%) of nanocellulose dispersions in distilled water amphiphobicity. Silane is a silicon chemical consisting of were prepared at room temperature. A piece of cleaned a hydrolytic center which can react with hydroxyl groups and the substrate was dipped into the well-dispersed nanocellulose 2 long tail of organic substituents. Many kinds of silanes have aqueous solution for 5 h at room temperature. Then, the been used for the generation of amphiphobic surfaces. Jin substrate was taken out from the dispersion solution and dried 23 Published on 25 January 2016. Downloaded by Taiyuan University of Technology 08/08/2016 04:39:29. et al. studied a superamphiphobic aerogel formed through the overnight at 50 C under vacuum. As such, the nanocellulose- chemical vapour deposition of a membrane with various kinds modied papers were obtained. of silane, in which 200 mL of (tridecauoro-1,1,2,2- tetrahydrooctyl) trichlorosilane was used to generate amphi- 2.3 Amphiphobic treatment phobicity. Gonçalves et al.19 studied superhydrophobic cellulose nanocomposites using two kinds of uorosiloxanes. 500 mLof A piece of nanocellulose-modi ed paper was further treated with 50 mL of FOTS in a 25 mL bottle, which was sealed with 1H,1H,2H,2H-per uorooctyl triethoxysilane was applied and a cap and placed in an oven at 90 C for various periods (1–9 h). obtained a water contact angle of 146.8 on their modi ed cellulose ber surface. Even silane is an active chemical for Then, the FOTS-treated paper was stored under vacuum at 50 C producing amphiphobic surfaces, although the environmental overnight for the removal of the unreacted chemical. issues of using it are a concern. Decreasing the amount of silane used in the modication will be a selective way to reduce the 2.4 Characterization harmfulness to nature.