Cellulose from cotton fibers was functionalized through a dissolution–regeneration process with phosphonate-based ionic liquids (ILs): 1,3-dimethylimidazolium methylphosphonate [DIMIM][(MeO)(H)PO2] and 1-ethyl-3-methylimidazolium methylphoshonate [EMIM][(MeO)(H)PO2]. The chemical modification of cellulose occurred through a transesterification reaction between the methyl phosphonate function of ILs and the primary alcohol functions of cellulose. The resulting cellulose structure and the amount of grafted phosphorus were then investigated by X-ray diffraction, ICP-AES, and ¹³C and ³¹P NMR spectroscopy. Depending on the IL type and initial cotton / IL ratio in the solution, regenerated cellulose contained up to 4.5% of phosphorus. The rheological behavior of cotton cellulose/ILs solutions and the microscale fire performances of modified cellulose were studied in order to ultimately prepare flame retardant cellulosic materials. Significant improvement in the flame retardancy of regenerated cellulose was obtained with a reduction of THR values down to about 5–6 kJ/g and an increase of char up to about 35 wt%.

中文翻译：

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使用基于膦酸盐的离子液体的阻燃功能化棉纤维素

来自棉纤维的纤维素通过溶解-再生过程与基于膦酸盐的离子液体 (IL) 功能化：1,3-二甲基咪唑甲基膦酸酯 [DIMIM][(MeO)(H)PO2] 和 1-乙基-3-甲基咪唑甲基膦酸酯 [ EMIM][(MeO)(H)PO2]。纤维素的化学改性是通过 IL 的膦酸甲酯功能和纤维素的伯醇功能之间的酯交换反应发生的。然后通过 X 射线衍射、ICP-AES 和 13 C 和 31 P NMR 光谱研究所得纤维素结构和接枝磷的量。根据溶液中的 IL 类型和初始棉花 / IL 比率，再生纤维素含有高达 4.5% 的磷。研究了棉纤维素/ILs 溶液的流变行为和改性纤维素的微尺度防火性能，以最终制备阻燃纤维素材料。通过将 THR 值降低至约 5-6 kJ/g 和炭增加至约 35 wt%，再生纤维素的阻燃性得到显着改善。