Water-borne conducting SBR (styrene butadiene rubber) composites containing surface-modified multi-layered graphene sheets (MLGSs) were prepared using a simple heterocoagulation process. Three different types of MLGSs were used and compared; raw, carboxylated, and cetyltrimethyl ammonium bromide (CTAB)-stabilized MLGSs. The SBR latex was mixed with a well-dispersed MLGS aqueous dispersion and heterocoagulated using a flocculant, polyaluminium chloride (PAC), at elevated temperatures. After particle growth and successive stabilization steps, the particulate SBR/MLGS composites were prepared in the size range, 10-100 µm. The CTAB-stabilized MLGSs were dispersed more effectively in the SBR matrix owing to their electrostatic attraction with the negatively charged SBR colloid particles. The MLGS-containing the SBR composites showed improved thermal stability and electrical conductivity. Importantly, the percolation threshold for the electrical conductivity was achieved at a low MLGS concentration, i.e., 0.5 wt%, using this heterocoagulation process.

To carry out miniemulsion polymerization of styrene in the presence of carbon black, carbon black was hydroxylated using potassium permanganate with the aid of a phase transfer catalyst, tetrabutyl ammonium bromide (TBABr). The hydroxylated carbon black was further reacted with oleic acid. The surface modification of carbon black with oleic acid was confirmed by FTIR, XPS, and TEM. The oleic acid-coated carbon black was successfully microencapsulated by polystyrene using miniemulsion polymerization. Polymerization failed when pristine carbon black was used. However, satisfactory conversion (> 96%) was achieved using the oleic acidmodified carbon black. The existence of a polystyrene layer was confirmed by TEM. In contrast the pristine carbon black, the oleic acid-coated carbon black did not act as a radical scavenger during polymerization.

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