Full Length ArticleFabrication of superhydrophobic cotton fabrics by grafting of POSS-based polymers on fibers
Graphical abstract
Cotton fabrics were treated with 3-mercaptopropyltriethoxysilane via chemical vapor deposition to get thiolfunctionalized fabrics, then turned superhydrophobic by grafting of POSS-based polymers via thiol-ene click chemistry.
Introduction
About from the beginning of 2000, superhydrophobic surface has attracted wide attention from academic and industrial aspects, due to their unique water-repellent and self-cleaning properties [1], [2], [3], [4], [5], [6], [7], as well as emerging some applications, such as oil–water separation [8], [9], [10], [11], anti-icing [12], [13], [14], anti-fouling [15]. There are many substrates that can be imparted with superhydrophobic property, for example, metal [16], glass [17], wood [18], textiles [19], etc. However, among these substrates, textiles are favored by researchers due to their low cost, easy processing, easy coloring, and can be produced at large area.
Techniques for preparing superhydrophobic surfaces can be generally divided into two categories. One is to modify a rough surface with a material of low surface energy; the other is to build a rough surface using a low surface energy material, the latter of which is the focus of this paper. Recently, polyhedral oligomeric silsesquioxanes (POSS) as a class of developed materials have received a great deal of attention for potential water or oil repellent coatings. POSS is an organic-inorganic hybrid material with a well-defined cage-like structure of general size among 1–4 nm [20], [21], [22], [23], [24], [25], [26]. The inorganic part is composed of SiOSi, giving it good mechanical, thermal stability. The organic part has good reactivity [21], [24], [25], making POSS molecules able be covalently bonded to polymers and the resulting nanocomposites exhibited remarkable performance, such as higher usage temperature, improved mechanical strength, enhanced fire retardation and processability, improved chemical and mechanical resistance [27], [28].
Some articles recently have reported the preparation of superhydrophobic, oleophobic fabrics with POSS modified fibers, in which of them POSS plays two roles. One is POSS as a nanoparticle, which is blended with a hydrophobic polymer [29] or fluorinated alkyl silane [30], [31] then through dip coating POSS composites onto fibers to get a superhydrophobic textile. POSS nanoparticle provides some rough structure and lower surface energy. The other is POSS as a monomer, can be covalently bonded to polymers for modification, then through spray deposition [32], dip coating [33], [34] methods to deposit POSS modified polymers onto fibers to prepare a superhydrophobic textile. Among these works, in addition to using POSS to reduce surface energy, most of them also use fluorine-containing low surface energy substances, such as perfluoro POSS and long chain fluorosilane, which have potential risk to organic organism. Dip coating and spray deposition are volatile techniques and it is difficult to control the uniformity of the coating [35]. Therefore, exploring new methods is necessary to boost the POSS based materials into applications of superhydrophobic surfaces.
In this work, we attempted to construct a superhydrophobic cotton fabric by modification of fibers with mercapto silanes, and covalently bonding of POSS-based polymers onto the mercaptosilane modified fibers via thiol-ene click chemistry, as shown in Fig. 1. The prepared fabric shows excellent resistance to different pH solutions and organic solvents. Additionally, the as-prepared superhydrophobic fabric has antifouling properties.
Section snippets
Materials
Vinyltrimethoxysilane was purchased from Wuhan University Silicone New Materials Co., Ltd, Wuhan, China. Pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) and 3-mercaptopropyltriethoxysilane (MPTES) were purchased from Sigma-Aldrich. 2,2-dimethoxy-2-phenylacetophenone (DMPA) was purchased from Aladdin. Sodium hydroxide was obtained from Tianjin Hengxing Chemical Reagent Co., Ltd. Octavinyl-POSS (OV-POSS) was synthesized using a previously described method [36]. Anhydrous ethanol,
Effect of the ratio of OV-POSS to PETMP on the wettability and wear resistance on the fiber surface
In this work, the POSS-based polymer was synthesized in situ using OV-POSS and PETMP monomers by thiol-ene click reaction in a step-growth pathway [38], [39], in which the thiol and vinyl functional groups are nearly equal consumption. OV-POSS monomer is highly hydrophobic and PETMP monomer is hydrophilic. Therefore, the ratio of OV-POSS to PETMP plays a critical role in deciding the surface wettability. Fig. 2(a) shows the CA and SA changes with the ratios of OV-POSS to PETMP. It was found
Conclusions
POSS-based polymers were grafted on the surface of the fibers to fabricate superhydrophobic cotton fabrics. The superhydrophobic cotton fabrics have strong resistance to acid, alkali, organic solvents, and UV irradiation. Introduction of the POSS-based polymers makes the fabrics not only meet the requirement of rough structure by accumulation formed nanoparticles on fibers but also lower the surface energy of the fabric surface. This method might be suitable for other substrates for the
Acknowledgements
This work was supported by National Natural Science Foundation of China, China (51572161), The National Key Research and Development Program of China, China (2017YFB0307700), Key Scientific Research Group of Shaanxi province, China (2013KCT-08), and Scientific Research Group of Shaanxi University of Science and Technology, China (TD12-03).
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