How a bio-based epoxy monomer enhanced the properties of diglycidyl ether of bisphenol A (DGEBA)/ graphene composites Lijun Cao, ab Xiaoqing Liu, * a Haining Na, a Yonggang Wu, b Wenge Zheng a and Jin Zhu * a A bio-based epoxy monomer (GA-II) was synthesized from renewable gallic acid. The aromatic group contained made it capable of being absorbed onto the surface of graphene via strong p–p interactions, which was proven by Raman spectra and UV spectra. The GA-II anchored graphene was easily homogeneously dispersed in the epoxy resin. After solidification, the graphene/epoxy composites demonstrated superior performances in terms of good mechanical properties, excellent thermal conductivity, as well as high electrical conductivity. With the addition of only 2 wt% GA-II/graphene, the tensile strength, tensile modulus, flexural strength and flexural modulus of the composites were improved by 27%, 47%, 9% and 21%, respectively. The thermal and electrical conductivities were also improved by 12-fold (from 0.15 to 1.8 W m 1 K 1 ) and 8 orders (from 7.0 10 15 to 3.28 10 5 s cm 1 ), respectively. This work provided us with an environmentally friendly agent with high efficiency for graphene dispersion and demonstrated an efficient method for fabricating epoxy/graphene composites with superior properties. 1 Introduction Graphene, characterized by a single-layered two-dimensional (2D) structure, has attracted tremendous attention in recent years due to its high values of aspect ratio, well-dened thermal conductivity, unique mechanical properties and excellent elec- trical properties. 1–5 It has been considered useful in various applications, such as memory devices, 4 hydrogen storage, 6 solar cells 7 and polymer composites. 8–10 As for its application in polymer composites, graphene is usually used as an effective inorganic ller to improve their electrical, thermal and/or mechanical properties. 1,8,11–14 However, due to the high surface area and strong van der Waals forces, graphene has a pronounced tendency to aggregate together and its predicted properties fail to be fully reached. 15–17 Therefore, many efforts have been made to improve its dispersion and interface inter- actions in polymer matrixes so as to demonstrate its nano- enhancement effect. The functionalization methods of graphene could be summarized into two categories. One is covalent bonding and the other is non-covalent wrapping via p–p interactions. For the former method, a large number of polymer segments or reactive sites, such as polystyrene, 18 poly(t-butylacrylate) 19 and epoxides, 20 are usually employed to functionalize gra- phene via graing-from or graing-to approaches. For example, Fang et al. demonstrated an effective method to covalently gra polystyrene chains onto the surface of gra- phene sheets by diazonium addition/ATRP to prepare poly- styrene composites with a prominent reinforcement effect. 21 S. Ganguli et al. prepared the epoxy composite lled with silane chemically functionalized graphene and an improved thermal conductivity was obtained. 22 Apparently, the gra- ing of polymer segments or reactive sites onto the graphene sheets could result in better dispersion and enhanced properties. However, these methods tend to alter, or even destroy, the desirable properties of graphene, especially its inherent electronic properties and thermal conductivity. 8 The non-covalent functionalization is based on van der Waals forces or p–p interactions between the surfactants and the sp 2 hybridized atoms of graphene, which is deemed to be a promising method to avoid defects and preserve almost all of its original characteristics. Many surfactants or polymers containing aromatic groups, such as poly(glycidyl methacrylate) containing localized pyrene groups (Py- PGMA), 8 poly(methyl methacrylate), 23 polystyrene 1 and poly- vinylpyrrolidone (PVP) 24 have been employed to function- alize or wrap graphene via p–p interactions using ultrasonic, solution mixing, melt blending or in situ polymerization. 1,4 a Ningbo Key Laboratory of Polymer Materials, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Zhenhai District, Ningbo 315201, China. E-mail: [email protected]; [email protected]; Fax: +86-574- 86685186; Tel: +86-574-86685283 b College of Chemistry and Environmental Sciences, Hebei University, Baoding, Hebei 071002, China Cite this: J. Mater. Chem. A, 2013, 1, 5081 Received 31st December 2012 Accepted 20th February 2013 DOI: 10.1039/c3ta01700a www.rsc.org/MaterialsA This journal is ª The Royal Society of Chemistry 2013 J. Mater. Chem. A, 2013, 1, 5081–5088 | 5081 Journal of Materials Chemistry A PAPER Published on 20 February 2013. Downloaded by Guangdong Technology University Library on 11/15/2022 1:46:09 AM. View Article Online View Journal | View Issue
How a bio-based epoxy monomer enhanced the properties of diglycidyl ether of bisphenol A (DGEBA)/ graphene composites
May 19, 2023
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Related Documents
