Contents lists available at ScienceDirect Diamond & Related Materials journal homepage: www.elsevier.com/locate/diamond Manufacturing functionalized mono-crystalline diamond containing electrospun fibers reinforced epoxy composites with improved mechanical characteristics Mohib Ullah a,b , Jamal Seyyed Monfared Zanjani c,d,e , Leila Haghighi Poudeh c,d,e , Mohammad Siddiq b , Burcu Saner Okan a,c,d,e,⁎ , Mehmet Yıldız c,d,e , Yusuf Menceloglu c,d,e a Sabanci University Nanotechnology Research and Application Center (SUNUM), Tuzla, Istanbul 34956, Turkey b Quaid-I-Azam University, Department of Chemistry, Islamabad 45320, Pakistan c Sabanci University, Faculty of Engineering and Natural Sciences,Tuzla, 34956, Istanbul, Turkey d Sabanci University, Integrated Manufacturing Technologies Research and Application Center, Tuzla, 34956, Istanbul, Turkey e Sabanci University-Kordsa, Composite Technologies Center of Excellence, Istanbul Technology Development Zone, Sanayi Mah. Teknopark Blvd. No: 1/1B, Pendik, 34906, Istanbul, Turkey ARTICLE INFO Keywords: Composites Diamond crystal Fibers Mechanical properties characterization Surface structure ABSTRACT Diamond in polymeric composites provides superior mechanical and thermal properties due to its controllable surface chemistry and large accessible surface area. Homogeneous dispersion of diamond in matrix and improved interfacial bondings between diamond and matrix are two important issues to achieve high performance and prevent structural failures in composite manufacturing. In the present work, the surface of submicron scale mono-crystalline diamond was functionalized by hydrazine hydrate and then dispersed in polymethyl methacrylate (PMMA) matrix homogenously by electrospinning technique. This process circum- vented aggregations of diamond particles and provided homogeneous dispersion in polymer matrix. Structural morphologies of diamond reinforced PMMA electrospun fibers were adjusted by tailoring polymer concentra- tion, diamond content, flow rate and applied voltage to attain an ideal fiber structure having continuous network without beads. PMMA was used as a polymeric carrier to improve the bonding interactions with epoxy matrix. Flexural tests indicated that the addition of 1 wt% functionalized diamond based electrospun fiber in epoxy matrix improved flexural modulus by 36.4% and flexural strength by 28.1%. Therefore, controlling the surface chemistry of diamond provides better interfacial interactions in reinforcing agent and thus load transfer was realized efficiently in epoxy specimen. In addition, thermal stability of epoxy composites was improved by the addition of diamond particles in electrospun structure. 1. Introduction Carbon based polymer composite materials with high specific strength and stiffness, excellent manufacturability, and superior corro- sion resistance have attracted a great deal of attention in aerospace, energy, and biology applications [1–4]. Diamond is sp 3 form of carbon and has a superior hardness and thermal conductivity and high Young's modulus [5]. Also, its size and structural properties are not affected by increasing temperature, which makes it suitable reinforcement for high temperature working conditions [6,7]. Diamond containing polymeric fibers can be a promising reinforcing agent in composite production [8]. Polymeric fibers have been produced by applying several techni- ques such as electrospinning [9], nanolithography [10], template synthesis [11], multi-component spinning [12] and melt-blowing [12]. Among these techniques, electrospinning is novel and feasible process to fabricate fibers with diameters ranging from nanometer to submicron level by using different types of polymers [13,14]. The integration of carbon particles in electrospun fiber provides additional strength and stiffness to the structure [15]. In addition, working parameters during electrospinning directly affect the fiber morpholo- gies. Surface tension and electrical forces have a significant influence on the shape change of viscoelastic fluids into polymeric jets [16]. The incorporation of carbon particles into electrospun solution can cause the instabilities in electrified jet during electrospinning, thus leading to structural deformations in electrospun fiber due to the changes in solution viscosity, physical forces and aggregations of http://dx.doi.org/10.1016/j.diamond.2017.04.018 Received 15 January 2017; Received in revised form 19 April 2017; Accepted 24 April 2017 ⁎ Corresponding author at: Sabanci University Nanotechnology Research and Application Center (SUNUM), Tuzla, Istanbul 34956, Turkey. E-mail address: bsanerokan@sabanciuniv.edu (B. Saner Okan). Diamond & Related Materials 76 (2017) 90–96 Available online 25 April 2017 0925-9635/ © 2017 Elsevier B.V. All rights reserved. MARK