Cellulose Microgel Toughening of Starch Nanocomposites: Exploiting the Advantages of Micro-Nanoscale Networks

The imperative shift from fossil-based, nonbiodegradable plastics to ecofriendly and biodegradable alternatives stands as a cornerstone of sustainable societal progress. However, the high cost of biodegradable polymers, e.g., poly(butylene adipate) terephthalate (PBAT), hinders the transition to sustainable plastics. And the commonly used biodegradable fillers, such as plasticized starch (PLS), weaken the mechanical performance of biodegradable composites. Cellulose microgels (CM) are micrometer-sized particles consisting of cellulose nanofibers (CNF) with a micronanometer hierarchical architecture. In this work, we show the superior performance of CM in toughening nanocomposites in binary system (CM/PLS) and ternary systems (CM/PLS/PBAT) as compared to CNF. The use of CM simultaneously increases the stress-at-break, Young’s modulus, and strain-at-break, resulting in enhanced toughness, which is compromised by using CNF. CMs hold great potential as novel natural toughening agents for industrial polymers by the typical melt blending process.