Optimizing multilevel interactions of paper straws using modified cellulose nanocrystal-based coatings to enhance PLA crystallization and microplastic capture efficiency

Disposable plastics make up 80 % of marine waste, threatening aquatic ecosystems. Over time, these plastics decompose into harmful microplastics (MPs), which can potentially enter the human body. This study presents a novel PLA-CO_x coating (where ‘x’ represents the concentration of cellulose nanocrystals and organically modified montmorillonite (CNC-OMMT)), designed to enhance the performance of paper straws by mimicking Chinese candle dip molding. Incorporating CNC-OMMT encourages crystallization through interface-induced dynamics and multi-level interactions within the PLA structure. At the same time, the strong layer-by-layer interactions between the paper fiber network and the PLA-CO_x composite have led to an impressive tensile strength of up to 48 MPa. The water absorption rate after 120 min is only 4.4 %, and the migration rate in various beverage simulants remains within the standard limit. Notably, the PLA-CO_x composite straws exhibited a degradation rate of 50.7 % in soil within three months. Additionally, the discarded straws effectively captured polystyrene microplastics (PS MPs) in water through physical entrapment and chemical adsorption, demonstrating a stable and efficient capture efficiency of 45.8 % over 12 h, thereby achieving sustainable waste management.