The Preparation And Performance Research Of Using Granhene Oxide To Surface-modified PLA Film

In order to protect the environment and alleviate the petroleum crisis, reducing the use ofpetroleum-based plastic materials and deveoloping the biodegradable eco-friendly plasticmaterials are the research focus of packaging material. So far, Poly(lactic acid)(PLA) is one ofthe most widely used biodegradable plastic materials. As a packaging film material, PLA has agood transparency, and excellent mechanical properties, and it’s biocompatible. However, thebarrier properties of PLA film is not good enough, which greatly limites its application inpackaging. Graphene Oxide (GO) is one of the most important derivatives of Graphene.Graphene Oxide also has a similar two-dimensional lamellar structure to Graphen, and it hasexcellent mechanical properties, and it’s biocompatible, too. What’s more, GO is a barrier fillerof high quality and its preparation is simple and safe, have a broad application prospects.Here the Layer-by-layer (LBL) assembling technique has being used to prepare multilayerGraphene Oxide/Polyethyleneimine (GO/PEI) membrane, which deposited onto the surface ofPLA film to improve the barrier properties. The results show that multilayer (GO/PEI)nfilm hasan excellent oxygen barrier property, as the concentration of GO is0.5mg/ml, and the number oflayers is only4, Oxygen Permeability has decreased more than99%; but its water vapor barrierproperty is unsatisfactory, the Water Vapor Transmission (WVT) only decreased15.12%; Afterbeing surface modified by Graphene Oxide, PLA film still has a good transmittance and goodmechanical properties. Then, in order to improve water vapor barrier property of PLA film, here,we modified Graphene Oxide by Cetyltrimethyl Ammonium Bromide (CTAB) to get m-GO,using m-GO and PEI to assemble multilayer (m-GO/PEI)nmembrane onto the the surface ofPLA film. Testing their water contact angle proved that m-GO had improved the hydrophobic ofthese multilayer membrane effectively: under the same condition, the water contact angle of(m-GO/PEI)16PLA film is40.20ohigher than (GO/PEI)16PLA film; and WVT of the(m-GO/PEI)16PLA film has decreased40.73%, compared (GO/PEI)nPLA film, the water vapor permeability has gotten an obvious decline.On the basis of previous work, to further improve the water vapor barrier properties of PLAfilm, make it obtain a wider range of application, SiOxwas deposited onto the surface of thesemultilayer membranes by Sol-Gel. Here, these multilayer membranes are also called compositesfilm.The existence of SiOxhas filled the space between GO/PEI and m-GO/PEI layers and theirsurface. As we can see from the AFM and water contact angle images, the surface roughness andwater contact angle of (GO/PEI)nPLA film has been improved by SiOx, while, the (m-GO/PEI)nPLA film has gotten a opposite effect. Through reducing the probability of the water moleculesadsorbed by GO layers, SiOxhas declined the WVT of (GO/PEI)nPLA film. When the numberof layer is16, the Reduction WVT is41.63%. And SiOxdoes not have the same effect on WaterVapor Permeability of (m-GO/PEI)nPLA film, since m-GO layers has had a better hydrophobicitself.