ARTICLE IN PRESS JID: JTICE [m5G;August 8, 2018;1:24] Journal of the Taiwan Institute of Chemical Engineers 000 (2018) 1–9 Contents lists available at ScienceDirect Journal of the Taiwan Institute of Chemical Engineers journal homepage: www.elsevier.com/locate/jtice Improving barrier performance of transparent polymeric ﬁlm using silk nanoﬁbril combine graphene oxide Suntorn Sudsandee a , Chien-Chieh Hu b,d,∗ , Ying-Ling Liu c , Suwalee Worakhunpiset a , Sawanya Loahaprapanon a , Wei-Song Hung b,d , Kueir-Rarn Lee d , Juin-Yih Lai b,d,e a Department of Social and Environmental Medicine, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchavithi Rd, Bangkok 10400, Thailand b Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, No. 43, Keelung Rd., Sec.4, Da’an Dist., Taipei 10607, Taiwan c Department of Chemical Engineering, National Tsing Hua University, #101, Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan d R&D Center for Membrane Technology, Chung Yuan University, Chung-Li 32023, Taiwan e Department of Chemical Engineering, National Taiwan University of Science and Technology, No. 43, Keelung Rd., Sec.4, Da’an Dist., Taipei 10607, Taiwan a r t i c l e i n f o Article history: Received 19 April 2018 Revised 13 July 2018 Accepted 17 July 2018 Available online xxx Keywords: Silk nanoﬁbril Graphene oxide Positron annihilation spectroscopy Oxygen transmission rate Water vapor transmission rate a b s t r a c t Silk nanoﬁbril was developed from Bombyx mori cocoons by thermodynamically driven, salts, and anneal- ing processes. Silk nanoﬁbril/polyethylene terephthalate composite ﬁlms were produced by casting differ- ent concentrations and amounts of silk nanoﬁbril solutions on polyethylene terephthalate ﬁlm. Then oxy- gen and water vapor transmission rates were determined. The results showed that oxygen transmission rate at optimum concentration of 0.30 wt% silk nanoﬁbril/polyethylene terephthalate ﬁlm was reduced by 33.4%, while the water vapor transmission rate was decreased by 37.6%. Graphene oxide at different wt% were also mixed with silk nanoﬁbril solutions to develop silk nanoﬁbril/grapheme oxide/polyethylene terephthalate ﬁlms. The silk nanoﬁbril/grapheme oxide/polyethylene terephthalate ﬁlm developed from 0.15 wt% grapheme oxide decreased the oxygen transmission rate by 76.8% but did not signiﬁcantly af- fect the water vapor transmission rate. The morphology of the top surface of silk nanoﬁbril based bar- rier ﬁlm was investigated by using scanning electron microscope that showed micellar unit or nanoﬁb- ril aggregates formation. Fourier transform infrared spectroscopy and X-ray diffraction showed high β -sheet regions and crystallinity in 0.30 wt% silk nanoﬁbril/polyethylene terephthalate ﬁlm. Besides, the silk nanoﬁbril/polyethylene terephthalate and silk nanoﬁbril/grapheme oxide/polyethylene terephthalate showed smaller cavity size than polyethylene terephthalate that can reduce the oxygen and water va- por permeation. Transparent silk nanoﬁbril/polyethylene terephthalate and silk nanoﬁbril/grapheme ox- ide/polyethylene terephthalate ﬁlms might be a great potential material in ﬂexible electronics or food and pharmaceutical packaging. © 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved. 1. Introduction Silks are biopolymers traditionally obtained from insect co- coons, the long, continuous ﬁlament providing larvae protection from humidity, bacteria, molds, UV, etc. during metamorphosis [1]. Silk ﬁbers are composed of two ﬁbrous protein microﬁlaments that align in long axis (ﬁbroin) coated by a protective cover of sericin [2–5]. Large amounts of silk can be obtained from spun cocoons of Bombyx mori, an economically important insect abundant in ∗ Corresponding author at: Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, No. 43, Keelung Rd., Sec.4, Da’an Dist., Taipei 10607, Taiwan. E-mail address: cchu@mail.ntust.edu.tw (C.-C. Hu). nature. Due to this, silk from B. mori cocoons are used as natural polymer in several ﬁelds [6,7]. The silk ﬁber of B. mori cocoon contains ﬁbroin (70–80%), sericin (20–30%), wax matter (0.4–0.8%), carbohydrates (1.2–1.6%), inorganic matter (0.7%), and pigment (0.2%) [8]. Silk ﬁbroins con- sist of heavy chain polypeptides linked to light chain polypeptides via disulﬁde bonds [9,10]. The heavy chain is hydrophobic and con- tains blocks that form crystalline portion of about two-thirds and an amorphous region of about one-third [11]. The crystalline region consists of repeated sequence of Gly-Ala-Gly-Ala-X (X can be Ser or Try or Val) which form β -sheet crystalline structures stabilized by hydrogen bonds between protein chain [1,4,9]. There are two crystalline forms in silk ﬁbroin ﬁber from B. mori: silk I and silk II (β -sheet structure), silk I transforms into the β -sheet structure of Silk II with the application of mechanical strain or other energy https://doi.org/10.1016/j.jtice.2018.07.024 1876-1070/© 2018 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Please cite this article as: S. Sudsandee et al., Improving barrier performance of transparent polymeric ﬁlm using silk nanoﬁbril combine graphene oxide, Journal of the Taiwan Institute of Chemical Engineers (2018), https://doi.org/10.1016/j.jtice.2018.07.024