Graphene chemically synthesized from benzene at liquid–liquid interfaces Rodrigo V. Salvatierra a , Victor H.R. Souza a , Carolina F. Matos a , Marcela M. Oliveira b , Aldo J.G. Zarbin a, * a Departamento de Quı ´mica, Universidade Federal do Parana ´ (UFPR), CP 19032, CEP 81531-980 Curitiba, PR, Brazil b Departamento Acade ˆmico de Quı ´mica e Biologia, Universidade Tecnolo ´gica Federal do Parana ´ (UTFPR), CEP 81280-340 Curitiba, PR, Brazil ARTICLE INFO Article history: Received 6 March 2015 Accepted 7 June 2015 Available online 12 June 2015 ABSTRACT Herein, we report the total chemical synthesis of graphene assembled at a liquid–liquid interface through a chemical reaction starting from benzene as a monomer. The reaction occurs at the benzene/water liquid interface, taking advantage of the insoluble material (the growing graphene structures) assembling as a film, which allows a heterogeneous reaction with the precipitated material and a molecular construction of large graphene sheets (ca. 800 nm 2 or larger). A two-step polymerization mechanism has been proposed, involving the initial polymerization of benzene to poly-paraphenylene (PPP) and/or its oligomers, followed by subsequent Scholl reaction between disconnected aryl rings to graphene. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction Graphene is a one-atom thick, flat structure composed of sp 2 -hybridized carbon atoms and can be considered as either a two-dimensional (2D) crystal or a polymer. The first definition refers to the array of carbon atoms in a hexagonal lattice [1], whereas the second (chemistry) definition comes from considering graphene as being composed of repeating units, such as hexasubstituted benzene, also called areal monomers [2]. Independent of the definition, the periodicity and 2D confinement of graphene and other monolayered materials (e.g., BN, MoS 2 ) [3] are responsible for their unique properties, such as unusual electronic transport and optical characteristics [4], which differ largely from those of their 3D counterparts. These unique properties beg the question of whether novel 2D polymeric structures could exhibit some of the same behavior or give rise to new properties [5]. When considered as a polymeric structure, graphene sur- passes Staudinger’s concept by which a polymer is a linear chain of covalently bonded units. Its 2D polymer structure could also be the target for a great diversity of chemical routes for obtaining polymers [2]. The bottom-up approach for syn- thesize graphene could give control over their structure and size [6], which is precisely the limitation of the production of graphene using other common top-down routes (e.g., gra- phite oxide exfoliation) [7]. However, the chemical synthesis of large graphene sheets (and also carbon nanotubes) has not been successfully achieved, even though research on the fabrication of 2D polymers has been ongoing for over 80 years and has recently gained new life after the isolation of graphene [8,9]. The reasons for this are (1) the precipitation of insoluble graphene molecules as their size increases towards the chemical reaction, preventing in-depth charac- terization and further growth, and (2) the lack of selectivity in the shape and border structure [7]. http://dx.doi.org/10.1016/j.carbon.2015.06.016 0008-6223/Ó 2015 Elsevier Ltd. All rights reserved. * Corresponding author: Fax: +55 41 33613176. E-mail address: aldozarbin@ufpr.br (A.J.G. Zarbin). CARBON 93 (2015) 924 – 932 Available at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/carbon