Pre-phosphorylation for facile production of phosphorylated cellulose nanocrystals with high charge content: an optimised design and life cycle assessment

Phosphorylated cellulose nanocrystals (P-CNCs) are important derivatives of cellulose nanocrystals (CNCs), which have attracted much attention in food, cosmetics and biomedicines. However, the lack of suitable industrial manufacturing technology impedes the commercial application of P-CNCs. Here, we report a facile and green process combining pre-phosphorylation with mechanical fibrillation for P-CNC production. The pre-phosphorylation process was optimised to reduce raw material and energy consumption and improve the quality of P-CNCs, and the corresponding environmental performances were further evaluated by life cycle assessment (LCA). P-CNCs with high charge content (2.33 mmol g−1) and high crystallinity (87.3%) were obtained efficiently under an optimal molar ratio (cellulose biomass : NH4H2PO4 : urea) of 1 : 0.3 : 1.2 by curing at 150 °C for 30 min and showed superior flame retardant performance. Furthermore, compared with the present production processes based on in situ phosphorylation and post-phosphorylation, this facile process exhibited not only better environmental performance but also superior economic performance, as the LCA and economic evaluation results revealed. Therefore, this eco-efficient process exhibits great potential in the industrial production of P-CNCs.