Supporting Information Scalable realization of conductive graphene films for high-efficiency microwave antennas T. T. Tung a(Ϯ) , S. J. Chen b(Ϯ) , C. Fumeaux b(*) and D. Losic a(*) (a) School of Chemical engineering, the University of Adelaide, Adelaide, 5005 North Terrace, South Australia (b) School of Electrical and Electronic Engineering, the University of Adelaide, Adelaide, 5005 North Terrace, South Australia (Ϯ) T. T. Tung and S. J. Chen contributed equally (*) Corresponding to: Prof. Christophe Fumeaux and Prof. Dusan Losic Experimental details 1. Materials and Chemicals Graphite flakes from the Uley graphite mine (Australia) and expanded graphite were kindly supplied by Valence Industries, South Australia. Potassium permanganate (KMnO 4 ) was purchased from Sigma- Aldrich, Australia. Sulphuric acid (H 2 SO 4 , 98%), phosphoric acid (H 3 PO 4 , 85% w/w), hydrogen peroxide (H 2 O 2 , 30%), hydrochloric acid (HCl, 35%) were purchased from Chem-Supply, Australia. All chemicals were used directly without further processing. 2. Exfoliation of graphene and preparation of graphene conductive films Graphene was prepared by liquid phase exfoliation of expanded graphite (EG) in graphene oxide (GO) aqueous suspension, in which GO was prepared by the modified Hummer’s method as reported previously 1 . Briefly, for processing GO-mediated exfoliation of graphene from EG, 300 mg EG powders and 300 mL water were added in a 500 mL capped-round bottom flask, pre-sonicated with bath sonicator for 1 h, and then 100 mL GO suspension with concentration of 1mg/mL was added. The mixture was subjected to sonicate with a UIP1000hd (Hielscher) with sonotrode (diameter of 22 mm) at a power of 200 W, and amplitude of 80% for 10 h where the temperature was kept less than 40 ° C. Subsequently, the as-prepared suspension was left to stand for 1 day for setting down the large graphite particles, and the supernatant was extracted by centrifugation at 4200 rpm for 1 h, which led to the graphene being separated from the complex and precipitated in the GO supernatant. The graphene product was decanted, washed several times with water, and redispersed in water to make Electronic Supplementary Material (ESI) for Journal of Materials Chemistry C. This journal is © The Royal Society of Chemistry 2016