Sustainable food packaging using modified SiO2 nanofillers in biodegradable polymers†

The need to switch to bio-based, biodegradable and/or fully recyclable polymers is becoming increasingly clear, especially in the area of food packaging, which is a major contributor to plastic pollution. To meet this challenge, biodegradable polymers must not only be economically viable, but also have properties that match or better those of conventional fossil-based polymers, such as robust mechanical strength and efficient gas barrier properties. One promising route is the production of composite materials from biodegradable polymers and SiO₂ nanoparticles. However, the high surface energy of SiO₂ often leads to agglomeration of the filler in the hydrophobic polymer matrix, which compromises the integrity of the composite. Here we present an innovative approach in which the surface of silica nanoparticles is modified with L-lactic acid oligomers (OLLA), effectively reducing the agglomeration of the filler and improving processability. Using conventional polymer processing methods that comply with industry standards, we prepared PLLA and PHBV nanocomposites and evaluated the effectiveness of the modification using a novel SBF-SEM technique. Our results show that modified silica achieves better dispersion in the polymer matrix and yields 70% more independent particles in the nanocomposite. The introduction of OLLA-g-SiO₂ increases the oxygen barrier of PLLA by 38% while accelerating the biodegradation rate and improving the toughness of the eco-friendly nanocomposites. This innovative approach offers a sustainable solution that is set to revolutionise the landscape of green food packaging.