Raman Investigations on PS-PERB-PS – Graphene Nanocomposites

Polystyrene-Block-Poly(ethylene-ran-butylene)-Block-Polystyrene (PS-PERB-PS) and chloroform were purchased from Sigma Aldrich. Graphene was purchased from Cheaptubes. The block copolymer was dissolved in chloroform. Then the graphene powder was added to the solution. The obtained mixture was stirred at 2500 rpm for about 8 hours. Then, a high-power sonication homogenization step (500 W, 30 minutes) was necessary to obtain a good dispersion of graphene. During the sonication, the temperature of the mixture increased up to about 80 ^oC. The viscous solutions were poured on microscope slides and were introduced in an oven at 90 ^oC for 12 hours. Thermogravimetric analysis (using TA Instruments Q 50 equipment) was used to confirm the full removal of the solvent and to assess the effect of the nanofiller on the thermal stability of the polymeric matrix. Various nanocomposites containing different fractions of graphene in the block copolymer have been synthesized and investigated. Raman measurements at 532 nm and 785 nm have been performed using a Renishaw InVia spectrometer, at room temperature. The effect of the interactions between the polymeric matrix and the graphene nanofiller, as revealed by the shift of the main Raman lines assigned to graphene and PS-PERB-PS will be discussed.