Layered double hydroxide polymer nanocomposites for food-packaging applications

Layered double hydroxides (LDHs) constitute a large family of anionic inorganic clays having interesting and sometimes unexplored characteristics. They are natural, cheap, and simple to be produced, with a high degree of purity. In addition, they can be easily modified by means of organic molecules, and organic modification is an inevitable step for the intercalation of polymer macromolecules into the layers of LDH. The obtained hybrids can be used to prepare polymeric nanocomposites with new properties. The layered structure of LDHs enables the intercalation of polymer macromolecules, and hence the formation of polymer nanocomposites with peculiar functionalities for targeted applications. With appropriate host molecules, nanohybrid LDH molecules can be used as functional fillers able to protect packaged food from bacteria spoilage and pollutant environment. This chapter reviews the state of the art of LDH-active hybrids (i.e., antimicrobials, oxygen scavengers, etc.), with particular attention to their potential use in food-packaging applications. The incorporation process into polymer matrices (either biodegradable or not), the structure of these nanocomposites and the resulting properties (thermal, mechanical, and barrier) are also described. Possible trends and future perspectives are finally proposed and discussed.