From multilayers to coatings: Barrier, durability, and recyclability of mono-material food packaging under the EU Packaging and Packaging Waste Regulation

The EU Packaging and Packaging Waste Regulation (PPWR, Regulation (EU) 2025/40) ties packaging circularity to recyclability performance, recycled-content obligations, and restrictions on substances of concern. For flexible plastic and paper-based food packaging, traditionally built from multilayer laminates of polyolefins, polyamides, ethylene-vinyl alcohol, and aluminum, these requirements sharpen the trade-off between barrier performance and end-of-life compatibility. Combining peer-reviewed literature and industrial evidence, this review examines the shift from multilayers toward coated mono-material architectures, in which barrier functions migrate into thin wet-processed polymeric and hybrid coatings, or dry-deposited inorganic layers, on polyethylene, polypropylene, poly(ethylene terephthalate), and paper. On polymer films, the two routes reach overlapping oxygen barriers: on polypropylene at 23 °C and 50% relative humidity, oxide-coated films showed oxygen permeances of 0.5–6 cm 3 m⁻ 2 day⁻ 1 bar⁻ 1 , a single waterborne coating 2.75, and coating stacks below 0.1. They differ in how they fail (hydrophilic coatings at high humidity, inorganic layers under scratching and strain) and in how recyclability assessments rate them. On paper, a comparable barrier is declared for commercial barrier papers; a waterborne dispersion coating on paperboard was three to four orders of magnitude more permeable. In every architecture, the barrier must be topcoated or laminated: these auxiliary layers weigh on recyclability grading. Coatings and nanofillers alter migration and non-intentionally added substance risk in the pack and in food-contact recyclate. The most suitable coatings are therefore those that keep their barrier after converting and are removed or tolerated in recycling, not those with the best barrier on unconverted film.