Terpineol

All reagents were of analytical grade and solutions were prepared using ultrapure water (Millipore MilliQ system, TKA Germany). Silver nitrate (AgNO₃) and N-methyl-2-pyrrolidone (NMP, 99.9 wt%) were obtained from VWR Chemicals (Leuven, Belgium). Poly(acrylic acid) (PAA, M_w = 1800), hydrazine hydrate (N₂H₄; 50–60 wt%), ethylene glycol (EG; anhydrous, 99.8 wt%) and 3-morpholynopropylamine (MPA) were purchased from Sigma-Aldrich (Burlington, MA, USA). Terpineol (TpOH; mixed isomers, 98 wt%) was purchased from Alfa Aesar (Kandel, Germany). Ethanol (EtOH, 96 wt%), isopropyl alcohol (IPA; anhydrous, 99.5 wt%) and citric acid were obtained from Gram-Mol (Zagreb, Croatia). N,N′-diisopropylcarbodiimide (DCI) was bought from Merck (Darmstadt, Germany) and sodium hydroxide from Kemika (Zagreb, Croatia).

Graphite flakes (G) having particle sizes 200–300 µm were purchased from Graphenea, San Sebastian, Spain and melamine from Alfa Aesar, Kandel, Germany. Ethanol (absolute) and 2-propanol were obtained from Gram-Mol, Zagreb, Croatia, ethylene glycol from Sigma-Aldrich, St. Louis, MO, USA, and terpineol (mixture of isomers) from Alfa Aesar, Kandel, Germany. All the chemicals were of analytical grade and were used as received. melamine intercalated graphene nanosheets (M-GNS, 1–2 sheets) were obtained by a mechanochemical route and can be used without additional purification. Aqueous solutions were prepared with deionized water (Millipore Milli-Q, specific conductivity 0.059 μS cm^–1). Commercial polymeric stabilizing agents Solsperse 12000S and Solsperse 20000 were supplied by Lubrizol, Wickliffe, OH, USA. Surface mount light-emitting diodes for the proof of concept experiment were from Kingbright Electronic Co, New Taipei City, Taiwan; they were glued to the printed conducting traces using a conductive glue, Wire Glue, Anders Products, Melrose, MA, USA.