Multilayer biopolymer‐based flexible packaging films via layer‐by‐layer assembly: a comprehensive review

Abstract In the current market, petroleum based plastics or synthetic polymers covers a wide area over flexible packaging films; their drawbacks, such as non‐biodegradability, landfills, greenhouse gas emission, etc., are influencing researchers to shift towards multilayered biodegradable polymers. The layer‐by‐layer technique represents an alternate deposition of polymeric materials. The attraction between the layers is due to electrostatic attraction, van der Waals attraction, hydrogen bonding, and Schiff base linkage. Single‐layer film has several advantages such as cost‐effectiveness, but limited barrier properties (depending upon the material used), manufacturing simplicity, limited functionality, and other properties such as mechanical and optical. Whereas in multilayer film, the combination of layers' properties is enhanced, such as mechanical, active functionalities (e.g. antimicrobial, antioxidant, controlled release), oxygen and moisture barrier, and twist retention. Nowadays, researchers are finding alternative for replacement of petroleum‐based plastics, also known as synthetic polymers, with degradable biopolymers like chitosan, polysaccharides, alginate, soy protein, whey protein, poly(lactic acid), polyhydroxyalkanoates, and inorganic nanocomposites (clay, metal oxides) that have equivalent mechanical qualities. This review also discusses various characterization techniques like scanning electron microscopy, transmission electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, differential scanning calorimetry, and thermogravimetric analysis of multilayer flexible films. © 2026 Society of Chemical Industry.