Durable, robust and free-standing superhydrophobic poly(vinyl alcohol-co-ethylene) nanofiber membrane Annaso B. Gurav, Qihao Guo, Yifei Tao, Tao Mei, Yuan Wang, Dong Wang n School of Materials Science and Engineering, Wuhan Textile University, Wuhan, Hubei 430200, China article info Article history: Received 19 March 2016 Received in revised form 27 May 2016 Accepted 21 June 2016 Available online 24 June 2016 Keywords: PVA-co-PE NFM Superhydrophobic Robust Durable FT-IR XPS abstract A simple and straightforward method for preparation of durable, robust and free-standing super- hydrophobic poly(vinyl alcohol-co-ethylene) nanofiber membrane (PVA-co-PE NFM) is reported. PVA-co- PE nanofibers were synthesized by melt-blend extrusion and phase separation method, and their membrane was prepared by nanofiber suspension coating technique. Post-surface chemical modification on prepared NFM was performed by anchoring low surface-energy fluoroalkylsilane (FAS) molecules using dip-coating to get superhydrophobic NFM. The FAS-modified NFM had depicted a high water contact angle of 151°, robust water-repellence and sustained durability in superhydrophobic behavior against corrosive solutions and UV-radiations. & 2016 Elsevier B.V. All rights reserved. 1. Introduction Owing to their typical characteristics such as large surface-to- volume ratio, ability to provide micro-pores, flexibility in surface functionalization, good mechanical performance and so on; class of micro/nano fibrous materials have been widely investigated for variety of fascinating applications [1]. Numerous natural entities have exhibit special wetting or non-wetting properties which manifests their unique functional mechanism [2]. For instance, water repellence characteristics of naturally occurring silver rag- wort leaves is attributed to its hierarchical rough-textured fibrous surface morphological features [3]. Such a fibrous architecture provide thoughtful ideas to researchers for the development of artificial water-repellent fibrous membranes for various promising practical applications. PVA-co-PE is a kind of hydrophilic thermo- plastic polymer which has distinguished properties such as non- toxicity, biocompatibility, good mechanical strength, and abundant reactive hydroxyl sites associated with vinyl units that offers ease in functionalization for achieving novel properties to virgin poly- mer. Previously, we have successfully demonstrated that, functio- nalized PVA-co-PE NFM is a versatile candidate for several sig- nificant applications [4–6]. For this time we report an affordable method of preparation for durable, robust and superhydrophobic PVA-co-PE NFM. 2. Experiment PVA-co-PE nanofibers were prepared by melt-blend extrusion and phase separation method [7]. In short, bio-based cellulose acetate butyrate (CAB) and PVA-co-PE pellets were mixed together at a certain proportion and processed through a co-rotating twin- screw extruder in temperature range of 463–503 K. The composite melt extrudates were hot drawn at the die exit by a take-up device keeping a drawn ratio of 20–25 and cooled in air to room tem- perature. CAB was the matrix material which supported to the formation of PVA-co-PE nanofibers. It was extracted by simple dissolution process in acetone for at least 24 h to obtain PVA-co-PE nanofibers. Then obtained nanofibers were dispersed into aqu- eous-alcoholic solution using a high speed blender to get homo- genous and stable nanofiber suspension. This suspension was coated onto polyester fabric and after complete drying, a free- standing PVA-co-PE NFM was inevitably detached from polyester fabric surface without any cracks. Post-surface chemical mod- ification process on as-prepared NFM was performed in ethanoic solution of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FAS) for 12h. The vol% of FAS in ethanol was varied from 0.0 to 1.0 to find highest water repellent state of PVA-co-PE NFM. FAS-modified NFMs were first dried in ambient conditions and then heated in vacuum at 353 K for a day. Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/matlet Materials Letters http://dx.doi.org/10.1016/j.matlet.2016.06.086 0167-577X/& 2016 Elsevier B.V. All rights reserved. n Corresponding author. E-mail address: wangdon08@126.com (D. Wang). Materials Letters 182 (2016) 106–109