Transparent Films Based on PLA and Montmorillonite with Tunable Oxygen Barrier Properties

• Published in: Biomacromolecules Vol. 13; no. 2; pp. 397 - 405
• Main Authors: Svagan, Anna J, Åkesson, Anna, Cárdenas, Marité, Bulut, Sanja, Knudsen, Jes C, Risbo, Jens, Plackett, David
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 13.02.2012
• Subjects: Applied sciences; Bentonite - chemistry; Chitosan - chemistry; Exact sciences and technology; Food Packaging - methods; Food, Preserved; Forms of application and semi-finished materials; Humidity; Membranes, Artificial; Microscopy, Electron, Transmission; Oxygen - chemistry; Polyesters - chemistry; Polyethylene Terephthalates - chemistry; Polymer industry, paints, wood; Quartz Crystal Microbalance Techniques; Sheets and films; Surface Properties; Technology of polymers; Self-assembled layer; Clay; Self assembly; Oxygen; Transparency; Transport properties; Montmorillonite; Film; Multiple layer; Experimental study; Coated material; Gas permeability; Lactic acid polymer; Humidity effect; Optical properties; Morphology; Oside polymer; Chitosan; Manufacturing
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/bm201438m

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.