Developing innovative bioplastic formulations for advanced applications by using biomass-derived additives

The transition towards a circular plastic economy needs new strategies for the development of plastic materials that completely fulfil the requirements of sustainability. Bio-based plastics offer multiple advantages in terms of potential replacement of traditional plastics, but their actual renewable carbon content is frequently much lower than expected due to the presence of non-renewable additives. This doctoral research aimed to address this demand by testing biomass-derived additives for biopolymers like polyhydroxybutyrate-co-valerate (PHBV), polylactide (PLA), and chitosan, to develop new fully bio-based plastics for advanced applications. Different bio-additives were tested, starting from wood-waste-derived tannins. These polyphenols were used both to develop PHBV-based films with potential application in smart food packaging and to prepare chitosan-based hydrogels for active wound healing. When combined with PHBV, tannins improved its antioxidant, antimicrobial, UV-blocking, and gas barrier properties, also introducing a unique ammonia-responsive color change, useful as a spoilage indicator for food. When combined with chitosan, tannins acted as crosslinkers to obtain stable hydrogels, with excellent swelling, mechanical, and adhesive properties, strong antioxidant effects, and UV-blocking abilities, revealing potential in enhancing wound healing. Subsequent research focused on other phytochemicals, particularly the flavonoid quercetin and the alkaloid berberine. PLA-based food packaging films aimed at enhancing the storage of highly perishable foods like blueberries were characterized, revealing the flavonoid superior performance. Further research has then focused on testing a fully bio-based plasticizer, obtained from a solvent-free esterification of glycerol and triphenylacetic acid, to mitigate PLA’s limiting properties and substitute fossil-based polymers for food packaging. After detailed characterization, real-food experiments with fresh pears showed its positive impact in extending food shelf-life, with comparable performance to polyethylene-based commercial packaging. These findings demonstrated that bio-derived additives can effectively be employed in a circular economy, enhancing biopolymers for various applications and supporting the shift from conventional plastics to bioplastics.