Controlling the assembly of graphene based nanosheets within a rubber matrix: Nanocomposite morphology probed by measuring gas permeation and dielectric properties

Self-assembling of reduced graphene oxide (RGO) and graphene oxide (GO) platelets, as a tailored interconnected network within natural rubber and butyl rubber matrices, is proposed as a mean for obtaining nanocomposites with significantly enhanced functional properties as compared to unloaded rubber, i.e. gas barrier properties and electric conductivity, even at very low filler contents. Interestingly, the prescribed spatial arrangement of the nanoparticles ('segregated arrangement') results to be much more effective in improving properties than homogeneous dispersion ('not segregated' arrangement) of platelets, even at low loadings. The 'segregated' structure originates from the confinement of platelets within the interstices of the coagulated latex particles, which act as a template for the network formation. The platelets are assembled on the latex particles giving rise to spheres with a core-shell structure, with a partial or complete covering depending on graphene amount. Conversely, the 'not-segregated' structure is obtained by destroying this interconnected network by further processing the nanocomposite masterbatch via twin-roll mixing, thus determining a uniform orientation of exfoliated platelets.