Gas barrier polymer nanocomposite films prepared by graphene oxide encapsulated polystyrene microparticles

The dispersion and orientation of two-dimensional (2D) inorganic nanoplatelets in polymers are technical challenges faced in polymer nanocomposite manufacturing. This work demonstrates an effective way to facilitate the dispersion and orientation of graphene oxide (GO) nanoplatelets in a polymer matrix through encapsulating the polymer within a nanoplatelet shell. Briefly, few-layered GO nanoplatelets encapsulated polystyrene (PS) microparticles were synthesized by a Pickering suspension polymerization method. The synthesis conditions, morphologies, and barrier properties of the GO encapsulated PS spheres and the melt-compressed films are characterized. The addition of salt induces flocculation of GO onto the surface of the styrene monomer droplet, resulting in the formation of a multilayered GO shell as well as the sedimenting of the PS/GO particles during polymerization. The obtained GO encapsulated PS microspheres were purified, dried, and melt-compressed to form composite films. The oxygen permeability (expressed as transmission rate) of the PS/GO composite film containing 2 wt % GO was 526.02 ± 55.78 cm3 m–2 24 h–1—a reduction of 96% relative to the PS control film and 34% lower than the solution mixed PS/GO composite film. This indicates that the encapsulated PS spheres act as an effective carrier to facilitate the dispersion of GO. The orientation was realized by the following melt-compression process, which creates tortuous pathways hindering the permeation of gases through the PS matrix