Paper and Cardboard Packaging: From Cellulosic Substrates to Functional and Hybrid Architectures

Paper and cardboard are widely used in packaging due to their renewable origin, low density, printability, and established recycling infrastructures. However, monolithic cellulosic substrates are intrinsically limited by porosity and moisture sensitivity, resulting in inadequate barrier performance for demanding applications. Consequently, paper-based packaging has evolved toward functionalised systems based on coatings, multilayers, and hybrid architectures. This review adopts a system-level approach based on a structured and criteria-driven analysis of the scientific and technical literature to examine the transition from base cellulosic substrates to advanced paper-based packaging structures. The study integrates material composition, layer architecture, and interfacial phenomena, and develops a classification and interpretation framework that systematically links structural design variables to key performance domains, including barrier behaviour, mechanical integrity, converting compatibility, food-contact safety, and end-of-life management. Particular emphasis is placed on the role of functional layers as critical design variables governing both performance enhancement and circularity constraints. By systematically correlating structure, mechanisms, and functional outcomes, the analysis highlights the central trade-offs between barrier efficiency and recyclability and identifies design-for-recycling and controlled delamination as key strategies for the development of next-generation sustainable paper-based packaging.