Preparation And Research Of Functionalized Graphene/poly (Ethylene-co-vinyl Alcohol) Layer-by-layer Composite Film

Graphene nanosheets were successfully assenmbled on the surface of EVOH matrix under a parallel electric field by the functionalization of graphene. Two types of functionalized graphene/EVOH LbL composite films were prepared,and their performances were tested and evaluated.Using aryl diazonium salt as a functionalization agent, methoxybenzene group functionalized graphene (fGO) was prepared by the reduced graphene oxide (GO).During the functionalization process, the integrity of the exfoliated nanosheets was well maintained. A facile layer-by-layer (LbL) assembly process using solutions under a parallel electric field was used to constructmethoxybenzene group functionalized graphene oxide/poly(ethylene-co-vinyl alcohol) (fGO/EVOH) multilayer barrier films.The resulting films were the best moisture barrier even under a relative humidity of 99 % (e.g., 0.028 g m-2 s-1 atm-1 for (fGO/EVOH)20) and showed an excellent oxygen barrier (e.g., 0.05 cm3 m-2 d-1 atm-1 for (fGO/EVOH)20). Furthermore, the Young's modulus and tensile strength of the fGO/EVOH films were improved by more than 200% and 50% of that of the bare EVOH film, respectively.Using [2-(Methacryloyloxy)ethyl]trimethylammonium chloride as a functionalization agent, [2-(Methacryloyloxy)ethyl]trimethylammonium chlorid functionalized graphene oxide (mGO) was prepared. During the functionalization process, the negative charged graphene nanosheets changed to positive charged. mGO could be assembled on an EVOH matrix at a voltage of 45 kV under a parallel electric field. The films had an outstanding moisture property (e.g., 0.019 g m-2 s-1 atm-1 for(fGO/EVOH)20) and remarkable barrier property (e.g., 0.07 cm3 m-2 d-1 atm-1for(fGO/EVOH)20). Besides, mGO/EVOH composite film showed superior antibacterial activity. Compared with bare EVOH film, mGO/EVOH film showed bacteria activity of 13.6 % for E. coli and 5.1 % for S. aureus. More importantly, mGO nanosheets exhibited no toxicity for HeLa cell even the concentration of mGO reached up to 50?g ml-1. The HeLa viability maintained around 89 %.The fGO/EVOH and mGO/EVOH LbL composite films have good moisture and oxygen barrier properties. Especially, the superior antibacterial activity and low toxicity of mGO/EVOH composite films make the films have broad prospects as packaging materials.