Microstructure, Polymer Dynamics, Polymer–Nanoparticle Interactions, and Rheology of Biodegradable Polylactic Acid Nanocomposites with Cellulose Nanocrystals: A Microscopic Perspective

The increasing demand for sustainable materials has accelerated research into biodegradable polymers as alternatives to conventional plastics. Polylactic acid (PLA), a leading biopolymer, offers promising biodegradability but often suffers from low mechanical strength. To enhance its properties, bioderived nanoparticles (NPs) can be incorporated to form biodegradable polymer nanocomposites (PNCs). However, a microscopic understanding of PLA-NP interactions remains limited, and interfacial incompatibility presents challenges for effective property optimization and warrants further investigation. In this study, we conduct a comprehensive analysis of PLA-based PNCs reinforced with cellulose nanocrystals (CNCs). Using small-angle scattering and quasi-elastic neutron scattering, we examine the effects of CNC incorporation on PLA's microstructure, dynamics, and macroscopic properties. Additionally, rheological measurements provide insights into how nanoscale interactions influence bulk mechanical behavior. Our findings contribute to a fundamental understanding of PLA/CNC nanocomposites, offering guidance for the rational design of high-performance, biodegradable polymer materials.