Department of Food Science, University of Copenhagen , Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
Biomacromolecules. 2012 Feb 13;13(2):397-405. doi: 10.1021/bm201438m. Epub 2012 Jan 9.
Polylactide (PLA) is viewed as a potential material to replace synthetic plastics (e.g., poly(ethylene terephthalate) (PET)) in food packaging, and there have been a number of developments in this direction. However, for PLA to be competitive in more demanding uses such as the packaging of oxygen-sensitive foods, the oxygen permeability coefficient (OP) needs to be reduced by a factor of ~10. To achieve this, a layer-by-layer (Lbl) approach was used to assemble alternating layers of montmorillonite clay and chitosan on extruded PLA film surfaces. When 70 bilayers were applied, the OP was reduced by 99 and 96%, respectively, at 20 and 50% RH. These are, to our knowledge, the best improvements in oxygen barrier properties ever reported for a PLA/clay-based film. The process of assembling such multilayer structures was characterized using a quartz crystal microbalance with dissipation monitoring. Transmission electron microscopy revealed a well-ordered laminar structure in the deposited multilayer coatings, and light transmittance results demonstrated the high optical clarity of the coated PLA films.
聚乳酸（PLA）被视为一种有潜力替代合成塑料（如聚对苯二甲酸乙二醇酯（PET））用于食品包装的材料，在这方面已经有了许多发展。然而，为了使 PLA 在更具挑战性的用途（如包装对氧气敏感的食品）中具有竞争力，需要将氧气透过系数（OP）降低约 10 倍。为了实现这一目标，采用层层（Lbl）方法在挤出 PLA 薄膜表面组装交替的蒙脱石粘土和壳聚糖层。当施加 70 个双层时，在 20%和 50%相对湿度下，OP 分别降低了 99%和 96%。据我们所知，这是 PLA/粘土基薄膜中氧气阻隔性能的最佳改进。使用带有耗散监测的石英晶体微天平对组装这种多层结构的过程进行了表征。透射电子显微镜显示出沉积的多层涂层中存在有序的层状结构，透光率结果证明了涂覆的 PLA 薄膜的高光学清晰度。
