Potential of polymer–clay nanocomposites as barrier materials

Early in the development of polymer–clay nanocomposites it was recognized that, due to the platy morphology of the smectic nanoparticles, the gas permeability of the composite would be altered considerably from that of the pure polymer. This improved barrier has major applications potential in the food and pharmaceutical industries. These composites have the additional advantage of maintaining clarity of display of packaged foods or medicines. The fundamental origin of the barrier properties exhibited by polymer–clay nanocomposites appears to derive largely from the physical morphology of the nanocomposites, but in some notable cases, this cannot be explained by the physical barrier of the nanoparticles.

The number and types of applications utilizing the barrier properties of polymer–clay nanocomposites are significant. In general terms the majority of applications involve the protection of food or drugs from the ingress of either oxygen or water vapor. In the area of flexible food packaging, the nanocomposites will not only protect the food from spoilage and improve shelf life, but also should allow down-gauging in applications where the existing packaging barrier is sufficient. Because of the size and refractive index of the clay nanoparticles, the packaging will also be transparent.