Vibrational Spectroscopy 74 (2014) 57–63 Contents lists available at ScienceDirect Vibrational Spectroscopy jou r n al hom ep age: www.elsevier.com/locate/vibspec Raman spectroscopy as a tool for the analysis of carbon-based materials (highly oriented pyrolitic graphite, multilayer graphene and multiwall carbon nanotubes) and of some of their elastomeric composites Liliane Bokobza ∗ , Jean-Luc Bruneel, Michel Couzi Institut des Sciences Moléculaires, UMR 5255, Université Bordeaux 1, CNRS-UMR 5255, 351 cours de la Libération, 33405 Talence Cedex, France a r t i c l e i n f o Article history: Received 24 March 2014 Received in revised form 4 July 2014 Accepted 25 July 2014 Available online 4 August 2014 Keywords: Raman spectroscopy Graphite Graphene Carbon nanotubes Nanocomposites Poly(dimethylsiloxane) Rubbers a b s t r a c t Raman spectra of highly oriented pyrolitic graphite, multilayer graphene and multiwall carbon nanotubes are carried out at different laser powers and different excitation energies. The effects of the laser heating and the double resonance Raman scattering are investigated as a prerequisite for a correct interpretation of the Raman spectra of carbon materials-based composites. The Raman spectra of multilayer graphene and multiwall carbon nanotubes embedded in a silicone matrix are also analyzed in an attempt to get some insights into the polymer–filler interface. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Carbon occurs in many forms and can be viewed as the building block of all other graphitic carbon allotropes of different dimen- sionality such as graphene, graphite or carbon nanotubes. Graphene is an atomically thick, two-dimensional (2-D) sheet composed of sp 2 carbon atoms arranged in a honeycomb structure, graphite (3- D carbon allotrope) is made of graphene sheets stacked on top of each other and separated by 3.37 ˚ A and carbon nanotubes are one- dimensional systems formed by one or several graphene layers rolled up into cylinders. These carbon nanomaterials that possess unique nanostructures, have attracted considerable interest on account of their outstanding electrical, mechanical and thermal properties. Incorporated into polymeric media, they impart to the host matrix, considerable property enhancements at much lower loadings than conventional fillers [1–6]. The dispersion of the nanofillers in the polymer matrix as well as the interfacial ∗ Corresponding author. Permanent address: 196 Boulevard Bineau, 92200 Neuilly-Sur-Seine, France. Tel.: +33 1 46 37 24 27; fax: +33 1 46 37 24 27. E-mail addresses: Liliane.Bokobza@wanadoo.fr, Liliane.Bokobza@espci.fr (L. Bokobza). bonding between the polymer–filler system are important param- eters in the extent of property improvement. Raman spectroscopy has become a key technique for the charac- terization of these materials ranging from highly oriented pyrolitic graphite (HOPG), graphene, carbon nanotubes, pyrocarbons or car- bon black. Because their Raman scattering is resonantly enhanced, they give rise to strong well-defined bands even if they are used at very small amounts in a polymer matrix. Raman spectroscopy has been shown to yield detailed information on the different car- bon nanostructures and on their degree of structural disorder [7] as well as on their state of dispersion [8] and orientation [9–11] in a host polymeric medium. Raman spectroscopy has also been used to probe the interactions between the polymer chains and the nano- tubes in carbon nanomaterials-based composites. Carbon species are deformed under application of a mechanical deformation and some of their Raman bands shift linearly to lower frequency with increasing strain as a result of a change in the interatomic force constants [12]. In composites submitted to an uniaxial strain, shifts and hence reinforcement are observed if stress transfer takes place from the polymer matrix to the carbon material [13,14]. The aim of this work is to explore the potential of Raman spectroscopy for the analysis of carbon nanomaterials-based composites. But interpretation of the results requires first deter- mination of the intrinsic spectroscopic properties of the carbon http://dx.doi.org/10.1016/j.vibspec.2014.07.009 0924-2031/© 2014 Elsevier B.V. All rights reserved.