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Top1. Introduction
Graphene a single atomic layer of graphite, has attracted much attention owing to its enhanced electrical, mechanical and thermal properties (Novoselov et al., 2004; Goenka, Sant, & Sant, 2014). Low weight and excellent thermal and mechanical stability of grapheme have made it to be a suitable filler/reinforcing material for most of polymers (Lim, Huang, & Loo, 2012). A wide variety of graphene-based composites have been reported with applications in biosensors (Lu et al., 2012), wound healing (Kasry et al., 2011), adsorption (Liu et al., 2012), bone tissue engineering (Goenka et al., 2014) and corrosion resistance (Gao et al., 2015).
Chitosan (CS) is a linear, semi-crystalline polysaccharide composed of (1→4)-2-acetamido-2-deoxy-b-D-glucan (N-acetyl D-glucosamine) and (1→4)-2-amino-2-deoxyb- D-glucan (D-glucosamine) units (Rinaudo, 2006). The presence of amino groups in the CS structure differentiates CS from chitin, and gives this polymer many peculiar properties. Indeed, the amino groups of the D-glucosamine residues might be protonated providing the higher solubility in diluted acidic aqueous solutions (pH < 6) (Leedy et al., 2011).
PVA, is a non-toxic, water-soluble synthetic polymer and has good physical which chemical properties and film-forming ability (Sharma & Chandy, 1992). The use of this polymer is important in many applications such as con- trolled drug delivery systems, membrane preparation, recycling of polymers and packaging. Studies on the mechanism of dissolution and changes in crystallinity and swelling behavior of PVA and its physical gel-forming capabilities, have been carried out (Paradossi, Lisi, Paci, & Crescenzi, 1996). PVA has bio inertness and it has many uses in medical applications such as artificial pancreas, hemodialysis, nanofilteration, synthetic vitreous and implantable medical device. Cell compatibility and blood compatibility of PVA have been studied extensively (Paradossi et al., 1996; Peppas, Mallapragada, & N.A., 1996; Lee & Jegal, 1999).
Composite blends of PVA and CS have been reported previously (Yang et al., 2004; Costa-Junior, Pereira, & Mansur, 2008, Hideto, Takashi, & Yoshiro, 1999). Composite films offer advantages due to improvements in stability, biocompatibility, and mechanical strength compared with the properties of the single components (Costa-Junior et al., 2008).
By combining a biopolymer such as CS with PVA some of the CS drawbacks are overcome. However, the extent of properties improvement was not as high as expected. Our approach in the present paper is to take advantage of complementary properties of the three materials, biocompatibility associated with CS, process ability and versatility associated with PVA and exceptional physical properties of graphene oxide (GO) in order to obtain a composite material which merges the above-mentioned properties (Pandele et al., 2014).