Polymer, Vol.53, No.17, 3756-3761, 2012
Ultralow percolation graphene/polyurethane acrylate nanocomposites
Polyurethane acrylate (PUA) are widely used as coating for automobile industry. Making these coatings electrically conductive would open up new applications. Using thermally reduced graphene (TRG) and in-situ polymerization we have created PUA nanocomposites with an ultralow percolation concentration of 0.15 wt% (0.07 vol%) graphene. Urethane-acrylate oligomer (UAO) was synthesized and diluted by tri-propyleneglycol diacrylate (TPGDA) to form flowable UAO/TPGDA mixture (UA). TRG was solvent-blended in UA to form uncured TRG/UA liquids and were polymerized by free radical polymerization with azobisisobutyronitrile (AIBN) initiator. Percolation concentrations of polymerized TRG/PUA nanocomposites occurred at 0.15 wt% (0.07 vol%), as determined by surface resistance measurements, bulk electrical conductivity, and modulus. TEM images revealed a homogeneous dispersion of TRG in PUA. Differential scanning calorimetry (DSC) was used to monitor the polymerization of TRG/UA uncured liquids and thermal properties of polymerized TRG/PUA nanocomposites. Polymerization heat, glass transition temperature, and polymerization temperature are independent of TRG loading, though polymerization temperature is similar to 10 degrees C lower in the absence of TRG. (C) 2012 Elsevier Ltd. All rights reserved.