In situ production of high filler content graphene-based polymer nanocomposites by reactive processing

This work deals with the preparation of graphene dispersed in a monomer (tetraethylene glycol diacrylate) and the subsequent polymerization of the latter to the corresponding polymer nanocomposite, which is the first obtained so far by direct polymerization of the graphene-dispersing medium. The method used for its obtainment allows reaching the highest concentration of graphene reported until now in any medium (9.45 mg mL(-1)); besides, a certain amount of graphene nanoribbons is also well visible. Furthermore, this goal is achieved by directly sonicating graphite without any chemical manipulation, which generally results in a final material still containing a significant number of defects. Because of its obtainment in the monomer itself, no filtration of graphene is needed, thus avoiding the reaggregation process to graphite, which partially compromises any previous exfoliation process. The obtained graphene-based polymer nanocomposites, fully characterized by Raman and transmission electron microscopy, differential scanning calorimetry, thermogravimetry, and dynamic-mechanical thermal analysis, exhibit a very homogeneous distribution of the graphene sheets within the polymer matrix. In addition, the interactions between the polymer and nanofiller are very strong, as evidenced by a significant increase in the T-g values even in the presence of a very low graphene content, together with a strong increase in the mechanical features (flexural and storage moduli). Finally, the thermo-oxidative stability of the polymer matrix is not affected by the presence of graphene nanosheets.