Yuuki Takatsuna

The development of sustainable polymer materials is a major challenge, driven by the increasing demand for environmentally sustainable alternatives to conventional plastics.

The growing need to reduce plastic waste has prompted the development of bio-based and biodegradable materials. Cellulose is attracting increasing attention as a sustainable filler candidate due to its renewability, abundance, and favorable mechanical properties. Its application in polylactic acid (PLA)-based composites has been extensively studied and has demonstrated improvements in mechanical strength, barrier properties, and processability. However, the use of nanocellulose in other biodegradable polymers such as poly(butylene succinate) (PBS) and poly(butylene adipate-co-terephthalate) (PBAT) remains limited, despite their industrial significance. In this study, we developed matrix-adapted cellulose nanoparticles by grafting PBS or PBAT onto cellulose regenerated from aqueous sodium hydroxide solution. Grafting was carried out via melt polycondensation, resulting in nano-sized particles with average sizes of approximately 100 nm for PBS and 175 nm for PBAT. These surface-modified particles exhibited improved thermal stability and high polymer content, reaching 25 wt% for PBS and 50 wt% for PBAT, indicating successful grafting, which is expected to facilitate compatibility with the target biodegradable matrices. This work provides a new approach for the rational design of biodegradable nanocomposites beyond PLA and contributes to the development of sustainable high-performance materials.

The incorporation of modified bacterial cellulose derived from agricultural waste improves biodegradable composites by reducing oxygen permeability and accelerating biodegradation while maintaining mechanical properties.

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.