EcoDesign of polymeric materials with thermally stabilized enzymes

The exponential increase in plastics production, particularly in the packaging sector, raises major concerns regarding recycling and end-of-life management. Current practices mainly rely on landfilling, incineration, and, to a lesser extent, recycling, with significant environmental impact. This scenario drives the search for bio-based alternatives aligned with circular economy principles. This thesis explores enzymatic systems as a sustainable strategy for plastic end-of-life management. Specifically, cutinase and lipase were immobilized on Layered Double Hydroxides (LDHs) to enhance thermal stability, enabling high-temperature processing, mechanical resistance, and controlled activation at end-of-life. Building on previous work on PBSA degradation by cutinase, the approach was extended to PBS and PLA. Experimental results showed immobilization consistently achieved >90% efficiency and markedly improved enzyme stability, with half-life increases up to seven-fold for cutinase and six-fold for lipase. Once released from LDH carriers, enzymes retained catalytic activity, enabling rapid and selective PBS degradation under controlled conditions. Complete degradation of PBS films and specimens occurred within 24–48 h depending on LDH composition and aging treatment. In contrast, PLA degradation was negligible under tested conditions, highlighting the need for further optimization. Overall, these results demonstrate that LDH–enzyme systems can act as intelligent additives for on-demand polymer degradation. The proposed strategy offers a scalable, environmentally compatible alternative to chemical recycling, advancing the development of recyclable and eco-friendly plastics in line with circular economy goals.