Tailoring Multi-Scale Structures of PLA/PPC/CNC-DDA Composites for High-Performance Green Mulch Film

The poor compatibility between biodegradable polylactic acid (PLA) and poly (propylene carbonate) (PPC) limits the blends' performance and hinders agricultural applications. In this study, hydrophobically modified cellulose nanocrystals (CNC-DDA) were prepared and incorporated into the PLA/PPC blend as nano-compatibilizers to improve the multi-scale structure of the blend for enhancing properties. CNC-DDA was uniformly dispersed at the PLA/PPC interface and in PLA, reducing PPC dispersed phase size and forming interfacial hydrogen bonds to enhance interfacial interactions. Furthermore, the CNC-DDA acted as effective heterogeneous nucleating agents, highly improving PLA's crystallization properties, including crystallinity, crystallization rate, and crystal size. Enhancements in morphology, interface, and crystallization multi-scale structure synergistically contributed to a significant increase in the tensile strength and elongation at break of the PLA/PPC blend, with improvements of approximately 93.9% and 43.1%, respectively. Furthermore, the incorporation of CNC-DDA improved the barrier property and biodegradability of the blend while maintaining favorable light transmittance. The excellent integrative properties of the PLA/PPC/CNC-DDA composite promoted cherry radish growth. This study presents a valuable and effective approach for enhancing polymer blend compatibility, offering new prospects for designing high-performance biodegradable agricultural mulching films.