Poly(meth)acrylate nanocomposite membranes containing in situ exfoliated graphene platelets: Synthesis, characterization and gas barrier properties

Here we report a novel method for the preparation of polymer nanocomposites containing in situ exfoliated graphene nanoplatelets. First, graphite particles were modified by sodium and ethylenediamine (en), yielding first-stage graphite intercalation compounds (GICs) containing [Na (en)](+) complex between carbon sheets. After subsequent ion-exchange reaction of the intercalated complex with quaternary ammonium salt bearing methacrylamide group, GICs possessing polymerizable double bond were obtained. It was found that the extent of [Na(en)] (+) complex intercalation as well as the ion-exchange reaction was significantly dependent on the type of the graphite used (natural vs. synthetic). GICs derived from natural graphite were further employed in the synthesis of polymer nanocomposites. Using NMR and TEM it was confirmed that the methacrylamide group in GICs participated successfully in the process of copolymerization with 2-hydroxyethyl methacrylate and 2-ethylhexyl acrylate, resulting in the in situ GICs exfoliation. The prepared nanocomposite membranes were further characterized using X-ray diffraction, DSC and TGA. Gas permeability measurements on the polymer composites were also carried out, confirming that the initial GIC was present in an exfoliated form.