Electrical and mechanical properties of PMMA/reduced graphene oxide nanocomposites prepared via in situ polymerization Sandeep Nath Tripathi • Parveen Saini • Deeksha Gupta • Veena Choudhary Received: 20 February 2013 / Accepted: 29 April 2013 / Published online: 14 May 2013 Ó Springer Science+Business Media New York 2013 Abstract We report the effect of filler incorporation techniques on the electrical and mechanical properties of reduced graphene oxide (RGO)-filled poly(methyl meth- acrylate) (PMMA) nanocomposites. Composites were prepared by three different techniques, viz. in situ poly- merisation of MMA monomer in presence of RGO, bulk polymerization of MMA in presence of PMMA beads/ RGO and by in situ polymerization of MMA in presence of RGO followed by sheet casting. In particular, the effect of incorporation of varying amounts (i.e. ranging from 0.1 to 2 % w/w) of RGO on the electrical, thermal, morphologi- cal and mechanical properties of PMMA was investigated. The electrical conductivity was found to be critically dependent on the amount of RGO as well as on the method of its incorporation. The electrical conductivity of 2 wt% RGO-loaded PMMA composite was increased by factor of 10 7 , when composites were prepared by in situ polymeri- zation of MMA in the presence of RGO and PMMA beads, whereas, 10 8 times increase in conductivity was observed at the same RGO content when composites were prepared by casting method. FTIR and Raman spectra suggested the presence of chemical interactions between RGO and PMMA matrix, whereas XRD patterns, SEM and HRTEM studies show that among three methods, the sheet-casting method gives better exfoliation and dispersion of RGO sheets within PMMA matrix. The superior thermal, mechanical and electrical properties of composites pre- pared by sheet-casting method provided a facile and logical route towards ultimate target of utilizing maximum fraction of intrinsic properties of graphene sheets. Introduction Since its discovery in 2004 by Novoselov et al. [1–3], graphene has drawn enormous scientific attention due to its unique properties and wide range of dependent applications [4, 5]. In particular, exceptionally high surface area along with exceptional electrical, thermal and mechanical prop- erties makes graphene an ideal nano-filler for functional nanocomposites. The interesting attributes of graphene as compared with CNTs includes high thermal conductivity, mechanical strength and superior electron transport prop- erties. In fact, single layer graphene with Young’s modulus of *1.0 TPa and tensile strength of *130 GPa, is the strongest material ever discovered [6]. However, to utilize its full potential, graphene needs to be dispersed in a suitable matrix to form composites. Recently, interest has grown significantly in polymer/graphene nanocomposites [7–9], e.g. Ruoff et al. [10] have reported polystyrene/ graphene composites, whereas, Wang et al. [11–13] have synthesized graphene-filled nanocomposites with various polymer matrices, (e.g. polystyrene (PS), poly(vinyl alco- hol) and low density polyethylene (LDPE)) and using number of strategies, viz. in situ polymerization, solution mixing and melt blending, respectively. Many dedicated attempts have also been made to formulate poly(methyl methacrylate) [PMMA]/GO nanocomposites using tech- niques such as solution casting, self-assembly, layer by Electronic supplementary material The online version of this article (doi:10.1007/s10853-013-7420-8) contains supplementary material, which is available to authorized users. S. N. Tripathi Á D. Gupta Á V. Choudhary (&) Centre for Polymer Science and Engineering, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110 016, India e-mail: veenach1951@gmail.com; veenac@polymers.iitd.ac.in P. Saini Polymeric and Soft Materials Section, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110 012, India 123 J Mater Sci (2013) 48:6223–6232 DOI 10.1007/s10853-013-7420-8