纤维素溶剂研究进展

ADVANCE IN SOLVENTS OF CELLULOSE

概述了纤维素溶剂的重要研究进展,主要包括N-甲基吗啉-N-氧化物(NMMO)在85℃以上高温可破坏纤维素分子间氢键,导致溶解;氯化锂/二甲基乙酰胺(LiCl/DMAc)在100℃以上可溶解纤维素;1-丁基-3-甲基咪唑盐酸盐([BMIM]Cl)和1-烯丙基-3-甲基咪唑盐酸盐([AMIM]Cl)离子液体,含强氢键受体Cl-离子,通过它们与纤维素羟基作用而引起溶解.氨基甲酸酯体系则是通过尿素与纤维素在100℃以上反应转变为纤维素氨基甲酸酯,然后再溶解于NaOH水溶液中;氢氧化钠/水体系,只能溶解结晶度和聚合度较低的纤维素;NaOH/尿素、NaOH/硫脲和LiOH/尿素水溶液体系,它们预冷至-5^-12℃后可迅速溶解纤维素.主要是通过低温产生小分子和大分子间新的氢键网络结构,导致纤维素分子内和分子间氢键的破坏而溶解,同时尿素或者硫脲作为包合物客体阻止纤维素分子自聚集使纤维素溶液较稳定.低温溶解技术不仅突破了加热溶解的传统方法,而且可推进化学"绿色化"进程.共引用参考文献50篇.

Advance in solvents of cellulose was summarized in this article. N-Methylmorpholine-N-oxide （NMMO） could break the intermolecular hydrogen-bonds of cellulose at the temperature higher than 85℃ leading to the dissolution. Lithium chloride/N, N-dimethylacetamide （LiC1/DMAc） were able to dissolve cellulose at 100℃ or higher. Ionic liquids such as 1-allyl-3-methylimidazolium chloride and 1-butyl-3-methylimidazolium chloride could dissolve cellulose, as a result of the strong hydrogen-bond acceptor （ Cl^- ）, which could associate with hydroxyl of cellulose. In carbamate system, cellulose derivate reacted with urea could be dissolved in NaOH aqueous solution. NaOH/H2O can only dissolve cellulose with low crystalline and degree of polymerization. Interestingly, cellulose could be dissolved rapidly in NaOH/urea, NaOH/thiourea and LiOH/urea aqueous systems pre-cooled to -5- - 12 ℃ . New hydrogen-bonded network structure between solvent and cellulose macromolecules could form to destroy the inter- and intramolecular hydrogen-bonds of cellulose. The inclusion complex hosted by urea or thiourea reduced the self-association of cellulose chains, leading to the good dispersion of cellulose. Low temperature dissolution is a great breakthrough to the traditional dissolving method, and also a strong driver force of the green chemistry. 50 References were cited.