Sustainable Dual-Network Cellulosic Bioplastics with Tunable Mechanical Properties and Biodegradability via Ring-Opening Polymerization

The global advancement of bioplastics development as an alternative material for traditional petroleum-based plastics is driven along with the emphasis on sustainable society. Cellulose, the most abundant natural polysaccharide, is a wood-derived renewable biopolymer widely used for sustainable materials. However, most cellulose-based bioplastics hinder their practical use because highly ordered structure of cellulose from extensive hydrogen bonding are difficult to process. To overcome these limitations, designing advanced materials by tailoring the structure and properties of cellulose requires innovative approaches and a deeper understanding beyond current knowledge. Furthermore, further studies are still needed to effectively balance and correlate biodegradability with mechanical properties of bioplastics. Our promising strategy is the fabrication of cellulose-based biopolymers using a dual-network via ring-opening polymerization, which allows precise tuning of mechanical properties and biodegradability for various applications. Dual-network bonds effectively dissipate energy under stress, enhancing toughness and fracture resistance, while providing a balance between rigidity and flexibility.<br/>In this study, we report a straightforward approach to control the mechanical properties and biodegradability be utilizing a cellulose network as the primary structure and incorporating the Y-junction network as the secondary structure. In the Y-junction network, lipoic acid and 2-hydroxyethyl acrylate engage in ring-opening polymerization to regulate the mechanical properties, while glycerol carbonate modulated biodegradability. We developed two types of dual-network bioplastics: dynamic bond bioplastic (DBP) and permanent bond bioplastic (PBP), both designed to control physical properties and biodegradability effectively. DBP is synthesized via thermal ring-opening polymerization and PBP is produced through radical-assisted ring-opening polymerization. Dual-network bioplastics using ring-strained disulfides have been shown to undergo ring-opening polymerization, resulting in the formation and linear disulfide crosslinking and can be further complemented by permanent reactions with alkenes to control network properties.<br/>Overall, our findings indicate that the ultimate tensile strength and elongation at break of these dual-network bioplastics can be finely tuned within the ranges of 8.8 to 193 MPa and 3.3 to 32.5%, respectively. Moreover, these bioplastics exhibit rapid biodegradability, achieving approximately 60% degradation within 2 weeks. Remarkably, our bioplastics demonstrate compatibility with plant growth, suggesting their potential to coexist with the ecosystem without disruption during the biodegradation process. This research provides a promising strategy to developing advanced bioplastics that meet sustainability goals while offering tunable performance characteristics.<br/>In summary, ring-opening polymerization and dual-network structures enable the creation of bioplastics with customized mechanical properties, tailored biodegradability, improved thermal stability, and enhanced processability. This versatility makes them suitable for a wide range of applications while addressing sustainability goals. This study not only contributes to the fundamental understanding of cellulose-based dual-network bioplastics but also paves the way for the development of high-performance, sustainable materials that align with the environmental and economic goals of a sustainable society.