Graphene Oxide Reinforced Poly(vinyl Alcohol) Nanocomposites

The first major success of polymer nanocomposites, where the filler has at least one dimension in the nanoscale, was reported by Kojima, Usuki et al. [1] from the Toyota Central R&D group. They demonstrated that nylon6/clay nanocomposites showed significant improvement in the mechanical and the thermal properties. Since then, works on the polymer nanocomposites have been conducted on a wide variety of polymer matrices, such as thermoplastics (styrenics, polyolefins), thermosetting polymers (epoxy resins and phenolics), as well as with various nanofillers, such as layered silicates and carbon-based nanomaterials. It was revealed that, using only a small amount of nanofillers, these nanocomposites show remarkable enhancement in materials properties, including mechanical properties [2,3], thermal properties [4] and gas-barrier properties [5], compared with the virgin polymers or conventional microfillers composites. In the last few decades, a variety of carbon-based nanomaterials, such as carbon nanotubes (CNTs) and fullerene have gained considerable attentions as nanofillers for the polymer nanocomposites because of their outstanding properties. For example, CNTs have been considered to be an ideal candidate for the reinforcement of polymer composites to enhance the mechanical, electrical, and thermal properties [6]. However, the success in imparting their amazing properties to the composites has been limited because of their tendency to form bundled agglomerates in the polymer matrices. In addition, their high cost, allegation against biosafety and the blackening of the products have been hampering their applications. Recently, nanodiamond (ND) has been produced and it has been exploited in some fields of nanotechnology as a new carbon-based nanomaterial [7-9]. We reported that ND achieved the high dispersibility in poly(vinyl alcohol) (PVA) matrix by using a simple casting method from aqueous medium. The resulting nanocomposites had excellent properties derived from ND, which can approach the values of single-crystal diamond [10]. Graphene, a two dimensional sheet of covalently bonded sp carbon atoms, has attracted a great deal of attention since the single sheet of graphene was isolated by Geim et. al. [11] The enormous amount of research has been made and the unique structure and properties of graphene were revealed [12]. One of the functionalized graphene materials, graphene oxide (GO), bears oxygen-containing functional groups on basal planes and edges of graphene. These groups attach the desired characteristic of water dispersibility to the pristine graphene sheet. Therefore, GO can be expected to be well-dispersed in polymer matrices and improve the issues of the conventional polymer/carbon-based materials. In this study, GO-reinforced PVA nanocomposites were prepared by a simple casting method from aqueous medium. The structure and properties of the PVA/GO nanocomposites were investigated.